Race and intelligence

File:Two Curve Bell.jpg

A single bell curve like these two was featured on the cover of the controversial book on race and intelligence The Bell Curve. Some regard this book as solid science, while others consider it a modern example of scientific racism. These are idealized normal curves comparing the IQs of Blacks and Whites in the US in 1981.

Race and intelligence are broad terms with many meanings that are often used to describe and measure human beings. The possibility of a relationship between race and intelligence has been a topic of considerable speculation, study, and debate, especially since the 19th century. The contemporary debate focuses on the nature, causes, and importance of racial and ethnic differences in intelligence test scores and other measures of cognitive ability. In the 19th and early 20th centuries research on race and intelligence was often used to argue that one race was superior to another, justifying poor outcomes and treatment for the "inferior race". Some early opinions about the differences among races grew out of stereotypes about non-whites developed during the period of colonialism and slavery.

Modern theories and research on race and intelligence are often grounded in two controversial assumptions:

• the social categories of race and ethnicity are concordant with genetic categories, such as biogeographic ancestry.
• Intelligence is quantitatively measurable (see psychometrics) by modern tests and is dominated by a unitary general cognitive ability.

Much of the evidence currently cited is based on IQ testing in the United States. There is much less data from other nations, in particular the developing world, and conclusions from the US data cannot automatically be generalized to the world as a whole. While the distributions of IQ scores among different racial-ethnic groups in the US overlap and often have a comparable range, groups differ in where their members cluster along the IQ scale. Similar clustering has been reported with related variables, such as school achievement, reaction time, and brain size. Most variation in IQ in the U.S. occurs within individual families, not between races. However, even small differences in average IQ at the group level might theoretically have large effects on social outcomes.

Several hypotheses have been proposed to explain why average IQ varies among racial-ethnic groups. Certain environmental factors, such as nutrition, are thought to moderate IQ in children, and other influences have been hypothesized, including education level, richness of the early home environment, and other social, cultural, or economic factors. The primary focus of the scientific debate is whether group IQ differences also reflect a genetic component. Hereditarianism hypothesizes that a genetic contribution to intelligence could include genes linked to neuron structure or function, brain size or metabolism, or other physiological differences which could vary with biogeographic ancestry.

The findings of this field have engendered significant controversy. Press coverage has given considerable positive attention to theories of genetic racial differences in intelligence even though there is no consensus among researchers regarding their validity. Upon publication, The Bell Curve, a controversial book that asserted that the gap in black and white IQ scores was, in part, genetic, received a great deal of positive publicity, including cover stories in Newsweek The New Republic, and The New York Times Book Review. Still, few strong propionates of the genetic theories of differences in intelligence do not think that press coverage has been positive enough. For example, media opinion of the role of genetic and environmental factors in explaining individual and group differences in IQ was studied in 1988 by conservative researchers Mark Snyderman and Stanley Rothman. They found it to differ from the opinion of mainstream experts.

Some critics question the fairness and validity of cognitive testing and racial categorization, as well as the reliability of the studies and the motives of the authors, on both sides. This has included accusations of bias based on the political ideals of the researchers or the funding agencies, such as the Pioneer Fund. Some critics fear the misuse of the research, question its utility, or feel that comparing the intelligence of racial groups is itself unethical. The disparity in average IQ among racial groups does not mean that all members of one group are more intelligent than all members of another. Robert A. Gordon, a Pioneer Fund media critic, ranking group averages "high" to "low" is not the same things as moral ranking from "good" to "bad" or an overall ranking of "superior" to "inferior". The conclusions of a few researchers: that racial groups in the US vary in average IQ scores, and the hypothesis that a genetic component may be involved, have led to heated academic debates that have spilled over into the public sphere.

Observations about race and intelligence also have important applications for critics of the media portrayal of different races. Stereotypes in media such as books, music, film, and television can reenforce old racist ideas and may influence the perceived opportunities for success in academics for minority students.

Background information

History

See also: Scientific racism

See also: Race (historical definitions)

In the 19th and early 20th century research on race and intelligence was often used to confirm that one race was 'superior' to another. Francisco Gil-White, author of Resurrecting Racism: The Modern Attack on Black People Using Phony Science and Stephen Jay Gould author of The Mismeasure of Man have suggested that some modern research has similar motives. Researchers such as Amanda Thompson and Elazar Barkan have suggested that "Scientific racism" has been used to perpetuate the idea of the intellectual inferiority of African Americans and that it was used to justify slavery and segregated education in America.

Slavery

Sir Francis Galton wrote on eugenics and psychometrics in the 19th C.

Anthropologist Franz Boas was a prominent 20th C. critic of claims that intelligence differed among races.

Because the Atlantic slave trade raised moral questions from its inception scientific theories about the mental capacities of Black people were provided to justify the enslavement of Africans. According to Alexander Thomas and Samuell Sillen during this time period the Black man was described as uniquely fitted for bondage because of what researchers at the time called "his primitive psychological organization." Hence, a well-known physician of the ante-bellum South, Samuel Cartwright of Louisiana, had a psychiatric explanation for runaway slaves. He diagnosed their attempts to gain freedom as a mental illness and coined the term "drapetomania" to describe it.

Scientific arguments about the mental inferiority of Black people were instrumental in keeping slavery alive as in institution in the United States. It was widely regarded that Black people lacked the mental capacity to handle freedom. Secretary of State John C. Calhoun arguing for the extension of slavery in 1844 said "Here (scientific confirmation) is proof of the necessity of slavery. The African is incapable of self-care and sinks into lunacy under the burden of freedom. It is a mercy to give him the guardianship and protection from mental death."

The writings of Sir Francis Galton, a British psychologist, spurred interest in the study of mental abilities, particularly as they relate to heredity and eugenics. Galton estimated from his field observations in Africa that the African people were 'two grades' below Anglo-Saxons' position in the normal frequency distribution of general mental ability his work was seen as scientific validation of Africans' mental inferiority compared with Anglo-Saxons.

Jim Crow and segregation

The scientific debate on the contribution of nature versus nurture to individual and group differences in intelligence can be traced to at least the mid-19th century. Charles Darwin wrote in his Descent of Man (VII, On the races of Man): "Their mental characteristics are likewise very distinct; chiefly as it would appear in their emotional, but partly in their intellectual faculties."

Lewis Terman wrote in The measurement of intelligence in 1916

"(Black and other ethnic minority children) are uneducable beyond the nearest rudiments of training. No amount of school instruction will ever make them intelligent voters or capable citizens in the sense of the world…their dullness seems to be racial, or at least inherent in the family stock from which they come…Children of this group should be segregated in special classes and be given instruction which is concrete and practical. They cannot master abstractions, but they can be made efficient workers…There is no possibility at present of convincing society that they should not be allowed to reproduce, although from a eugenic point of view they constitute a grave problem because of their unusual prolific breeding."

The opinion that there are differences in the brain sizes and brain structures of different racial and ethnic groups was widely held and studied during the 19th century and early 20th century. Average ethnic and racial group differences in IQ were first directly observed when analyzing the data from standardized mental tests administered on large scales during World War I.

Foremost amongst those researching this was Stanley Porteus of the University of Melbourne, who devised his maze test as early as 1919, applying it in his study of the Aborigines in the Kimberley region and Northern Territory of Australia (1929) and later the Kalahari tribesmen of southern Africa (1934). He also used it to assess the results of pre-frontal brain surgery on mental performance, publishing his results in 1931.

W.O. Brown, writing in The Journal of Negro History in 1931, wrote regarding early intelligence tests:

After the World War and during the severe agitation for the restriction of immigration, aimed especially at the Southeastern Europeans, tests came into a new usage...the tests revealed the inferior intelligence of various racial and nationality groups...The Southeastern Europeans and the Negroes especially came of badly in these tests...The results of the tests elevated their dogma of racial inequality from a mere prejudice to the dignity of a scientifically validated opinion.

Beginning in the 1930s, race difference research and hereditarianism — the belief that genetics are the primary cause of differences in intelligence among human groups — began to fall out of favor in psychology and anthropology after major internal debates. In anthropology this occurred in part due to the advocacy of Franz Boas, who in his 1938 edition of The Mind of Primitive Man wrote, "there is nothing at all that could be interpreted as suggesting any material difference in the mental capacity of the bulk of the Negro population as compared with the bulk of the White population." The hereditarian position was challenged by Boas' claim that cranial vault size had increased significantly in the U.S. from one generation to the next, because racial differences in such characteristics had been among the strongest arguments for a genetic role.

Modern work

File:Charles Murray.gif

Charles Murray (pictured) and Richard Herrnstein started the contemporary debate with The Bell Curve in 1994.

File:Stephen Jay Gould.png

In The Mismeasure of Man, updated in 1996, Stephen Jay Gould criticized many aspects of IQ research.

Inspired by the American eugenics movement, Nazi Germany implemented the T-4 Euthanasia Program in which roughly 200,000 mentally and physically disabled Germans were killed, and about 400,000 sterilized. The association of hereditarianism with Nazi Germany created an modern academic environment that has been very skeptical of suggestions that there are racial or ethnic differences in measures of intellectual or academic ability and that these differences are primarily determined by genetic factors.

In 1961, the psychologist Henry Garrett coined the term equalitarian dogma to describe the then politically fashionable view that there were no race differences in intelligence, or if there were, they were purely the result of environmental factors. Those who questioned these views often put their careers at risk.

The contemporary scholarly debate on race and intelligence may be traced to Arthur Jensen's 1969 publication in the Harvard Educational Review of "How Much Can We Boost IQ and School Achievement?" In this paper, he wrote on some of the major issues that characterize the genetic hypothesis of racial IQ differences, and on compensatory educational programs. Reports on Jensen's article appeared in Time, Newsweek, Life, U.S. News & World Report, and The New York Times Magazine.

In the 1980's Nobel Prize winner for his work on the development of transistors, William Shockley, postulated that the higher rate of reproduction among US African Americans was having what he termed a "dysgenic" effect (meaning an opposite of eugenics), ; especially as influenced by welfare subsidies (e.g., AFDC), which he opined, unintentionally encouraged childbearing by less productive mothers. . He described this work as the most important work of his career, even though it severely tarnished his reputation. Shockley's published writings on this topic, were largely based on the research of Cyril Burt. Shockley also proposed that individuals with IQs below 100 be paid to undergo voluntary sterilization . He was subsequently criticized by the media; however his involvement brought public recognition to several controversial topics.

Press attention returned to the issue of race and intelligence in 1994 with the publication of The Bell Curve, which included two chapters on the subject of racial difference in intelligence and related life outcomes. In response to The Bell Curve, Stephen Jay Gould updated The Mismeasure of Man in 1996. Among other things, he criticized the IQ test as a measure of intelligence, citing what he perceived as inherent racial and social biases as well as systematic flaws in the testing process.

Race

Main article: Race

See also: Race and multilocus allele clusters, Race (historical definitions)

Racial distinctions are generally made on the basis of skin color, facial features, inferred ancestry, national origin and self-identification in the United States. In an ongoing debate, some geneticists argue race is neither a meaningful concept nor a useful heuristic device, and even that genetic differences among groups are biologically meaningless, on the basis that more genetic variation exists within such races than among them, and that racial traits overlap without discrete boundaries. Concordant with this, a survey of cultural and physical anthropologists done in 1999 found that the concept of race was rejected by 69% of physical anthropologists and 80% of cultural anthropologists. Other geneticists, in contrast, argue that categories of self-identified race/ethnicity or biogeographic ancestry are both valid and useful, that these categories correspond with clusters inferred from multilocus genetic data, and that this correspondence implies that genetic factors might contribute to unexplained phenotypic variation between groups.

Worldwide, human populations are geographically bounded into five less than perfectly distinct continental areas: the Americas, Eurasia (including Europe, North Africa and West Asia), East Asia, Sub-Saharan Africa, and the Pacific Islands (including Australia). At least in the United States, self-identified racial labels correspond to geographic regions of genetic ancestry, with only a small number of individuals showing genetic cluster membership different from their self-identified race/ethnicity. People labeled Blacks have most of their ancestors from sub-Saharan Africa, Whites from Europe, the Middle East and North Africa, and East Asians from the north-western Pacific Rim. Hispanics form a genetically diverse group that includes many recent U.S. immigrants of mixed ancestry, and are more often called an ethnic group.

It is well known that many alleles vary in frequency across (and within) human populations. Most of this variation is selectively neutral, but a significant number show evidence of recent positive selection. These include genes involved in brain development and other neuronal functions, which have variants that have spread to high frequencies under selective pressure and now occur in substantially different frequencies in different global populations. The actual functions of these genes, and their effect, if any, on IQ is unknown. (Discussed below.)

The political, social and cultural structure of the United States is still weighted by race. It was only in the 1960s that racial discrimination became illegal in many areas of public and private life, including employment and housing, and some consider discrimination to remain prevalent. The national and state governments of the United States employ racial categorization in the census, law enforcement, and innumerable other ways. Many political organizations intend to represent the interests of specific racial groups. See the articles Race and Race (U.S. Census) for further discussion.

Intelligence testing

Main article: Intelligence

Further information: [[:Intelligence testing, intelligence quotient, general intelligence factor]]

Intelligence is most commonly measured using IQ tests. These tests are often geared to be good measures of the psychometric variable g (for general intelligence factor), and other tests that measure g (for example, the Armed Forces Qualifying Test and the SAT) also serve as measures of cognitive ability.

All such tests are often called "intelligence tests," though the use of the term "intelligence" is itself controversial. It is clear, however, that performance in these tests correlates with performance in similar life tasks (school grades and to a lower degree college grades). The correlation with many real-world results is lower. For example, while the correlation of IQ with job performance is strong, income is modestly correlated and accumulated wealth is only weakly correlated. The hereditary transmission of wealth via IQ is near zero. As commonly used, "IQ test" denotes any test of cognitive ability, and "IQ" is used as shorthand for scores on tests of cognitive ability. Some critics question the validity of all IQ testing or claim that there are aspects of "intelligence" not reflected in IQ tests. Historically, criticisms of the validity of IQ testing focused primarily on questions of "test bias", which has many related meanings. Several conclusions about tests of cognitive ability are now largely accepted by intelligence researchers:

• IQ scores measure many, but not all of the qualities that people mean by intelligent or smart (for example, IQ does not measure creativity, wisdom, or personality)
• IQ scores are fairly stable over much of a person's life
• IQ tests are predictive of school and job performance, to a degree that does not significantly vary by socio-economic or racial-ethnic background
• For people living in the prevailing conditions of the developed world, cognitive ability is substantially heritable, and while the impact of family environment on the IQ of children is substantial, after adolescence this effect becomes difficult to detect.

Average gaps among races on measures of intelligence

Main article: Race and intelligence (Average gaps among races)

File:US Europe Minorities IQ shuttergraph.png

Average IQ scores of minority groups from North American and Europe, excluding East Asians according to Template:AYref. No dates given for individual measurements. Lynn's datasets are criticized as being unrepresentative (Heredity April 2004, Volume 92, Number 4, Pages 359-360).

File:East Asians IQ year scatter.png

Average IQ scores of East Asians living in North American and East Asia according to Template:AYref. Lynn's datasets are criticized as being unrepresentative (Heredity April 2004, Volume 92, Number 4, Pages 359-360).

The gaps found between the average measures of races or ethnicities varies depending on methods used for racial grouping, the method and setting used to test intelligence, the health and economic situation of the test takers, the interplay between the culture of the person taking the test and the culture of those who made the test, and the period in history when the test was performed.

Depending on the way intelligence is measured a variety of gaps may be found between different racial and ethnic groups. Some groups that perform well on one task may do poorly on others. For example, Moroccan and North American individuals were asked in a study by Richard K. Wagner to remember patterns of Oriental rugs and pictures of everyday objects, such as a rooster and a fish. Moroccans who have long experience in the rug trade seemed to remember rug patterns better than the North American individuals. Linkewise, in 1979 Robert Serpell had Zambian and English children perform a number of tasks. He found that English children did better on a drawing task, but that Zambian children did better on a wire-shaping task.

The modern controversy surrounding intelligence and race focuses on the results of IQ studies conducted during the second half of the 20th century, mainly in the United States and some other industrialized nations. On average, a difference of approximately one standard deviation was observed in the US between the mean IQ score of Blacks and Whites as adults. Most recent attempted compilations of average IQ by race place Ashkenazi Jews at the top, followed by East Asians, Whites, Hispanics and Native Americans, and African Americans. Whether these gaps have narrowed or not, especially regarding children which may or may not later also cause a narrowing for adults, is, as noted below, debated.

Over the years, there has been variation in both the observed average IQ of groups, as well as the relative relationships between the average IQ of groups. Early 20th century measures typically found Blacks on the low end, and Whites on the high end. Based on studies from the 1960s and 1970s, Flynn found a slightly lower average IQ of Japanese- and Chinese American children compared to White counterparts. Recent contemporary measures place Blacks on the low end, and Asians on the high end.

Employment tests and school achievement

File:GRE by race.png

2001-2002 GRE scores - used in U.S. graduate schools - by race and ethnicity. The vast majority of the sample was White (76%), with all other groups less than 10% each. The data table also shows the majority of test takers were women (65%), and not representative of the general population. Particularly small sample sizes for minority racial groups make it difficult to make useful comparisons, especially among a self-selected group of GRE test takers.

Gaps are seen in other tests of cognitive ability or aptitude, including university admission exams such as the SAT and GRE, as well as employment tests for corporate settings and the military. Measures of school achievement correlate fairly well with IQ, especially in younger children. In the United States, achievement tests find that by 12th grade black students are performing on average only as well as white and Asian students in 8th grade; Hispanic students do only slightly better than blacks.

There is wide agreement that the U.S. Black-White gap among children and adolescents on achievement tests narrowed in the 1970s and 1980s, but stalled during the 1990s. On the basis of these data, Template:AYref argues that the gap in g has also narrowed to "0.6-0.7 standard deviation or approximately 10 IQ points". Both Template:AYref and Template:AYref argue that "gains in scholastic achievement do not equal gains in g, and the Black-White differences in g are as large as ever, even for measures of reaction time". Charles Murray argues that the U.S. Black-White gap on the SAT has increased in size to 1 SD from the 1990s to 2005.

IQ test score gap in the US

2003 SAT results by race/ethnicity. Redrawn from College Board statistics. College Board classifications, like other "race" classifications are not homogeneous; for example, "Asian" includes East Asians and South Asians; "White" includes Jewish Americans and other Whites. Similarly, "East Asians" are not homogenous, nor are "South Asians".

Distribution of SAT math scores by race and ethnicity. [20]

Percentage of race/ethnic groups that scored above 600 on the math SAT [21]

In the United States, the mean IQ score among Blacks has at times been measured as approximately 85 and the mean IQ score among Whites has at times has been measured as approximately 100; the mean IQ score of Latinos has been reported to be measured as approximately 89 for unspecified dates.

The mean score for people of East Asian and Jewish descent is usually higher than the mean score of Whites, but the extent of that difference is not precisely known. However, several studies place the median IQ of Ashkenazi Jews (who make up the overwhelming majority of American Jews) at approximately one standard deviation above the mean for other Whites, with the primary Jewish advantage in verbal reasoning and the East Asian advantage primarily in spatial reasoning. In The Bell Curve, Herrnstein and Murray report mean IQ scores for East Asians and Jewish Americans of 106 and 113 (on a scale where Whites = 103), respectively.

Similar gaps are seen in other tests of cognitive ability, including university admission exams such as the SAT and GRE as well as employment tests for corporate settings and the military (Template:AYref).

School achievement gap

Main article: Achievement gap

Measures of school achievement correlate fairly well with IQ (uncorrected correlations are highest for younger children because of restricted ranges of IQ at higher educational levels). The National Assessment of Educational Progress in the United States, find that by 12th grade Black students are performing on average only as well as White and Asian students in 8th grade; Hispanic students do only slightly better than Blacks. Closing this achievement gap is one of the aims of the No Child Left Behind act in the United States. The gap has been attributed to academic disengagement of Black students and parents and to environmental causes. Poverty in early childhood has long-lasting negative consequences for cognitive development and academic outcomes, as shown by numerous studies.

Attempts to redress the achievement gap in the U.S. include Head Start and related early intervention programs. Neither Head Start nor most other (more intensive) programs have been able to produce lasting gains in IQ or school achievement. Gains are lost after the programs end. Supporters note that they continue as long as the programs continue. The Abecedarian Early Intervention Project is an exception to this pattern, producing an IQ boost of approximately 5 points into adulthood.

Selected IQ data

Test	Black-White gap (SD)	White mean	Black mean	N	Age	Year	Reference
Overall g	1.10	-	-	6,246,729	Adults	Various	Roth, Bevier, Bobko et al. (2001)
AFQT '79	1.21	?	?	?	Adults	1979	reported in Herrnstein and Murray (1994)
AFQT '97	0.97	?	?	?	Adults	1997	reported in Murray (2005)
WAIS R	1.01	101.4	86.5	1,880	Adults	1981	Reynolds et al (1987)
WAIS III	?	?	?	?	Adults	1997	?
WJ	1.05	?	?	?	Adults & Children	2001	reported in Murray (2005); Schrank, F.A., K.S. McGrew, and R.W. Woodcock. 2001. Technical Abstract (Woodcock-Johnson III Assessment Service Bulletin No. 2). Itasca, IL: Riverside Publishing.
WJ	0.99	?	?	?	Children	2001	reported in Murray (2005); Schrank, F.A., K.S. McGrew, and R.W. Woodcock. 2001. Technical Abstract (Woodcock-Johnson III Assessment Service Bulletin No. 2). Itasca, IL: Riverside Publishing.
WISC IV	0.78	103.2	91.7	1,745	Children	2003	Prifitera, A., L.G. Weiss, D.H. Saklofske, et al. 2005. "The WISC-IV in the clinical assessment context." Pp. 3–32 in WISC-IV Clinical Use and Interpretation: Scientist-Practitioner Perspectives, edited by A. Prifitera, D. H. Saklofske, and L. G. Weiss.
WPPSI Full-scale IQ	.23	?	?	483	5 years	1990	Ethnic Differences in Children's Intelligence Test Scores: Role of Economic Deprivation, Home Environment, and Maternal Characteristics - Jeanne Brooks-Gunn, Pamela K. Klebanov, Greg J. Duncan, Child Development, Vol. 67, No. 2. (Apr., 1996), pp. 396-408.

U.S. Black and White IQ

There is disagreement about whether the results of IQ tests show a narrowing of the IQ gap, or if they do who has benefited. Template:AYref and Template:AYref argue that "the Black-White differences in g are as large as ever". Template:AYref found that the recent U.S. Black-White gap in g among adults is 1.1 sd, similar to characterization of the historical U.S. Black-White gap. In an analysis of standardization samples for the WAIS, WISC, SB, and AFQT, Template:AYref find evidence that the U.S. Black-White gap shrunk between 3 and 6 points from 1972 to 2002. These conclusions were challenged by Template:AYref, and a rejoinder was made by Template:AYref. Subsequently, Template:AYref analyzed testing data from the children of the 1979 NLSY cohort, concluding that "the B-W difference did not diminish on either academic achievement or cognitive tests for children born from the mid 1970s through the mid 1990s." To reconcile the contradictory findings, Murray suggests that "the effect that Dickens and Flynn found was concentrated among subjects born before the late 1970s". In 2006, Flynn and Murray debated the shrinking Black-White IQ gap. Both agree that the gap shrunk for children born before the late 1970s, however Murray believes the narrowing stopped while Flynn believes it has continued.

Several sources have argued that the U.S. Black-White gap varies with age. Template:AYref estimate that the 2006 U.S. Black-White IQ gap is 0.31 SDs at age 4, 0.63 SDs at age 12, 0.87 SDs at age 18, and 1.1 SDs at age 24. Using data from Template:AYref, Template:AYref estimates that the U.S. Black-White gap is 0.70 SDs in early childhood, 1.00 SDs in middle childhood, and 1.20 SDs in early adulthood. A study of children aged eight to twelve months found a U.S. Black-White gap of 0.06 SD.

World-wide IQ estimates

File:AverageIQ-Map-World.png

Calculated average IQ of indigenous populations from the book Race Differences in Intelligence by Richard Lynn. Lynn's datasets are criticized as being unrepresentative (Heredity April 2004, Volume 92, Number 4, Pages 359-360).

One review of the global cognitive ability data is Richard Lynn's 2006 Race Differences in Intelligence, which organizes the data by nine global regions, surveying 620 published studies from around the world, with a total of 813,778 tested individuals. Lynn's meta-analysis lists East Asians (105), Europeans (99), Inuit (91), Southeast Asians and Amerindians each (87), Pacific Islanders (85), Middle Easterners (including South Asians and North Africans) (84), sub-Saharan Africans (67), and Australian Aborigines (62). Searchlight magazine criticizes Lynn's publisher, which is not an academic press and for publishing “classic” Aryan and eugenic tracts.. Lynn has previously argued at length that nutrition is the best supported environmental explanation for variation in the lower range, and a number of other environmental explanations have been advanced (see below). Ashkenazi Jews score significantly higher than other groups (107-115) in the U.S. and Britain, but estimates of the average IQ of Ashkenazim in Israel may be somewhat closer to the European mean. In other data, Hispanics average 91 and African Americans average 87, though the latter is debated. Lynn's survey is an expansion by nearly four times of the data collected in his 2002 IQ and the Wealth of Nations with Tatu Vanhanen. 'IQ and the Wealth of Nations, which dealt with the relationship between IQ and economic development, received strong criticism from some for both error and alleged bias. Lynn argues the surveyed studies have high reliability in the sense that different studies give similar results, and high validity in the sense that they correlate highly with performance in international studies of achievement in mathematics and science and with national economic development.

Related groups sometimes vary greatly in IQ in different nations. Black Africans score much lower than blacks in the US, although Black Americans average about 7-20% European admixture. Some reports indicate that the black–white gap is smaller in the UK than in the U.S. Differences between groups of whites can also be seen, ranging to the low 90s in SE Europe (with a decrease also seen in brain size). In Israel, large gaps in test scores and achievement separate Ashkenazi Jews from other groups such as the Sephardi.

Cognitive ability scores for the ten global genetic clusters identified in previous genetic cluster analysis have been surveyed by Richard Lynn. Lynn regards these ten population groups as races, and extracts racial averages from 620 published studies surveying a total of 813,778 tested individuals. When taken as individual national averages, the data available, particularly regarding the developing world, is speculative due to limited sampling, year of testing, and varying type of cognitive ability test used. Lynn's previous work, including the trade book IQ and the Wealth of Nations with Tatu Vanhanen, have received widespread and strong criticism for both bias and error.

In general, Lynn lists East Asians and Europeans as demonstrating the highest average IQ, indigenous Americans and other Eurasians with intermediate average IQ, and Africans and Australian Aborigines with the lowest average IQ. According to Lynn, when the studies are grouped and taken as averages for the ten racial groups, the argument for their reliability is that, though additional evidence may be required to confirm some of the more limited estimates, many have very high reliability in the sense that different studies give similar results, as well as that they correlate highly with performance in international studies of achievement in mathematics and science and with national economic development. Lynn argues established environmental hypotheses can explain a substantial amount of these differences. The data set for sub-Saharan Africans around the world, the one most often criticized, is drawn from 155 different studies with a combined sample of 387,286 people. 57 of the studies are from countries in Africa, 54 from western countries, and 16 from non-western countries outside of Africa.

Some Ashkenazi Jews score significantly higher than any other group. An IQ of 70 is often associated with mental retardation, but deficits in adaptive behavior, such as telling the time, interacting socially, and looking after oneself, have only limited correlation with IQ, and are more important than IQ in determining whether a person is able to live an independent life.

IQ scores vary greatly among different nations for related groups. Blacks in Africa score much lower than Blacks in the US. Some reports indicate that the Black–White gap is smaller in the UK than in the U.S. American Blacks average about 7-20% European admixture; UK admixtures are not as well-studied. Many studies also show differences in IQ between different groups of Whites. In Israel, large gaps in test scores and achievement separate Ashkenazi Jews from other groups such as the Sephardi.

The IQ scores vary greatly among different nations for the same group. Blacks in Africa score much lower than Blacks in the US. Studies on African Blacks have yielded results of 65 and 69. Lynn (1991a) suggests this value should be rounded up to 70. The book IQ and the Wealth of Nations gives values for African nations ranging from 59 for Equatorial Guinea to 77 for Zambia.

Studies on Native Americans yield results ranging from 70 to 90. Lynn (1991a) suggests that the mean of several studies, 89, may be a reasonable approximation. Native Americans score higher on tests of spatial than verbal reasoning, a trait also shared with East Asians.

Some reports indicate that the Black–White gap is smaller in the UK than in the U.S. Other examples are Jews who score much lower in developing nations and Koreans who score much lower in Japan. There are also other examples of IQ score differences between close neighbors in the same nation, for example between French vs. Flemish speakers in Belgium, Slovaks vs. Gypsies in Slovakia, Irish and Scottish vs. English in Great Britain, and white speakers of Afrikaans vs. white speakers of English in South Africa. In Mexico, Whites score higher than Mestizos, who score higher than Native Mexican Indians.

There has been at least one comparative study on IQ scores in different European nations. The difference between the highest and lowest average national IQ scores is 8 points. There is a not statistically significant correlation between the country's latitude and its average IQ score. Also, Southern Europeans have a larger variation than Northern Europeans. Norwegians have less than half of the variability of Whites in the US while Italians and Bulgarians have about 150%.

In Israel, there is a large gap in test scores and achievement between the Ashkenazi Jews and other groups such as the Sephardi. Gaps are seen between Israeli Jews and Ethiopian Jews. A similar gap in IQ scores and achievement is seen between the Chinese and Malays in Singapore.

Both Lynn and Rushton have suggested that high IQ is associated with colder climates. To test this hypothesis, Templer and Arikawa (in press [doi:10.1016/j.intell.2005.04.002]; see discussion [25]) compare the national IQ data from Lynn and Vanhanen with data sets that describe national average skin color and average winter and summer temperatures. They find that the strongest correlations to national IQ were -0.92 for skin color and -0.76 for average high winter temperature. They interpret this finding as strong support for IQ-climate association. Other studies using different data sets find no correlation [26][27].

Reaction time

In 1991, Richard Lynn tested 1,468 9-year old children consisting of Blacks from South Africa, East Asians from Hong Kong and Japan, and Whites from Britain and Ireland. The content of the tests involved flipping a switch after one or more lights came on. Lynn found that the decision times (the time taken to make a decision about what to do) had a low correlation with IQ data on Raven's Progressive Matrices tests also administered during the same study, and that movement times (the time taken to execute the decision) did not show any correlation. He found that the Asians had the fastest decision times, followed by the Whites, and then by the Blacks. He also determined that the Black children had movement times that were substantially faster than those of Whites and Asians on certain tests. Studies by Jensen have shown similar patterns in response time on tests of arithmetic and international studies by Lynn have also asserted the same trend.

Template:A(Y)ref has stated that this allows for an extension of Spearman's hypothesis to include reaction time. Based on these results, they have concluded that the observed East Asian-White-Black differences have a neurological basis.

Brain size & structure

see also Craniometry, Neuroscience and intelligence

Mean cranial capacity (cc)

Measurement	East Asian	European	African
Autopsy	1351	1356	1223
Endocranial volume	1415	1362	1268
External head measurements	1335	1341	1284
Corrected for body size	1356	1329	1294
Mean	1364	1347	1267
Redrawn from Template:AYref, Table 12.1

Some historical and modern studies, using skull and head measurements, weighing of brains at autopsy, or more recently, magnetic resonance imaging, report racial differences in average brain size similar to those for IQ. Other studies have not found these results. These studies are usually accompanied by a great deal of controversy.

Reaction time

Average racial differences have been asserted to exist on tests of response time, although it is also argued that some of these differences can be explained by cultural phenomena. Jensen has used reaction time as a proxy for IQ, despite the low correlation..

Brain size and IQ

Many studies report that IQ has a moderate correlation with various measures of brain size. For example, a 2005 meta-analysis found that brain size correlates with IQ by a factor of approximately .40 among adults. The correlation was also found in some studies to hold true within families (where environmental factors can be considered to be similar), but in one study of 36 sibling pairs essentially zero correlation between brain size and IQ was found when comparing within families. Some studies have found racial differences in brain size. Professor Ulric Neisser claims that the studies comparing brain size by race "exhibit many internal inconsistencies", but that "there is indeed a small overall trend".

There are several hotly debated studies which have concluded that there are race differences in brain size. These studies are criticized as having not found racially-based difference, with critics arguing instead the the variation better explained in terms of geography. Perhaps the largest single study, Template:AYref analyzed more than 20,000 skulls from around the world, finding that brain size varied with latitude of biogeographic ancestry. Lieberman (2001) explains "...the relationship between latitude and cranial size is an example of Bergmann’s principle that crania are more spherical in cold climates because mass increases relative to surface area to conserve core temperatures...Beals, Smith, and Dodd emphasize that this relationship is independent of 'race'.".. By this they mean that brain size varies with latitude both within and between races. The biogeographical variation in brain size is widely described as an evolutionary adaptation to climate. Lieberman and other anthropologists (2001) have also made several other criticisms.

In 1970 Philip V. Tobias listed a number of difficulties involved in measuring and making meaningful comparisons of brain weight. These included equating subjects on age, sex, body size, temperature etc. In addition, brain development is plastic, and brain size may be affected by early environmental factors. Because of all these difficulties, Tobias concluded that no adequate racial comparative studies had actually been conducted.

The brain size of American Blacks reported in Tobias’s summary were larger than any White group, (which include American, English and French Whites) except those from the Swedish sub sample (who had the largest brains of any of the 77 national groups measured), and American Blacks were estimated to have some 200 million more neurons than American Whites (See Tobias 1970; Weizmann et. 1990).

Possibly related to the Flynn effect[28] is, as also previously observed by Boas, increase in cranial vault size and change in shape during the last 150 years in the US. These changes must occur by early childhood because of the early development of the vault. Brain size has increased for both American Blacks and Whites probably due to improved health and nutrition.

According to Lieberman, Rushton and others combining the correlations between race, IQ and brain size to establishes a correlation between race and IQ. This conclusion is strongly objected to by Lieberman and other scientists, both on the basis of the initial correlation asserted between race and brain size, and the progressively weak correlation as the studies are combined.

Old studies

Several studies from the 19th century and early 20th century found racial differences. Some showed that Whites had the largest measurements, which was the expected view at the time. This is different from more recent results [29][30](Rushton, 1991, 2000). As noted later, brain size and shape has changed greatly in the last century. In his 1839 Crania Americana, anthropologist Samuel George Morton reported that the mean cranial capacity of the skulls of Whites was 87 in³ (1426cm³), while that of Blacks was 78 in³ (1278cm³). Based on the measurement of 144 skulls of Native Americans, he reported a figure of 82in³ (1344cm³).

Morton's work has been criticized by Stephen Jay Gould, who alleged in his 1981 book The Mismeasure of Man that Morton was guilty of fudging data and "overpacking" the skulls with filler. Despite Gould's retabulation of Morton's data, however, the differences in brain size among different races still persist, with the data still showing a difference of about four cubic inches between modern Caucasians and Africans. Gould writes that the differences are "trivial", but current head of the controversial Pioneer Fund J. Philippe Rushton (1996) responds that a difference of only a single cubic inch equates to millions of neurons. In 1988, J. S. Michael remeasured a random sample of Morton's skulls and concluded that Morton had made very few errors. J. Philippe Rushton (1989) additionally reanalyzed Gould's retabulation, concluding that Morton had shown a pattern of decreasing brain size proceeding from East Asians, Europeans, and Africans.

Cortical neurons (billions)

East Asian	European	African
13.767	13.665	13.185
Source: Template:AYref

In 1873, Paul Broca found the same pattern by weighing brains at autopsy. Other historical studies showing a Black-White difference in brain size include Template:AYref, Template:AYref, Template:AYref and Template:AYref. In 1888, H.D. Rolleston reported that the brain of the Australian Aborigine weighed less than the brain of Blacks (44.3 oz, 1256 g) , which in turn weighed less than the brain of Whites (49 oz, 1389 g). He also found that the Australian brain was less convoluted than those of Whites (p. 33).

Some 19th century studies have also found that the brains of Whites are more convoluted than those of Blacks [31][32] or Australian Aborigines (Template:AYref, p. 33). It is often assumed that convolutions are associated with increased intelligence because they allow a greater surface area to be packed into a smaller volume. However, dolphins, who have shown no signs of super-human intelligence, have more convoluted brains than do humans (Ridgway, S.H. (1986). Dolphin brain size. p. 59-70 In: M.M. Bryden and R.J. Harrison (Eds) Research on Dolphins. Clarendon Press, Oxford. 478 pp.).

Is the IQ test score gap closing?

Long term White-Black gap in NAEP math scores [22]

Long term White-Black gap in NAEP reading scores [23]

Richard Nisbett and others have argued that the Black-White gap on various ability tests has narrowed from the 1970s to the 1990s, including the Equality of Educational Opportunity (EEO) survey, the National Longitudinal Study, the High School and Beyond survey, the National Education Longitudinal Study, and the National Assessment of Educational Progress program (NAEP). The Journal of Blacks in Higher Education found that although the Black-White gap on the SAT declined from 1976-1988, it has been increasing since 1988. Other studies find that the gap has been decreasing for most of the 20th century and that this trend continued during the nineties.

Jensen has argued that the Black-White differences in g have not narrowed. In support of this claim, he presents evidence that, while there have been gains in measures of acquired competency such as scholastic achievement, these improvements do not indicate gains in g. Jensen also argues that Black-White differences in g seen in measures of reaction time have not narrowed. A large meta-analysis using 6,246,729 samples found a mean Black-White score difference of 1.1 standard deviations (ranging from 0.38 to 1.46 depending on the g loading of the test). As to whether the IQ gap is narrowing, the authors speculated that any reduction was "either small, potentially a function of sampling error ... or nonexistent for highly g loaded" tests. Gottfredson agreed that the Black-White gap observed in the National Assessment of Educational Progress test has narrowed from 1.07 to 0.89 standard deviations. However, she then argues that reduction stopped by the mid-1980s and is compatible with stable group differences in g.

A large (21,260 children) and probably the most recent (1998) study found that the Black-White gap for young children in reading and math scores was much smaller than in earlier studies, and that all of the remaining difference could be explained by a few environmental factors. One possible explanation is that the Flynn effect started earlier for Whites but has now stopped, while continuing for Blacks.

IQ and Retardation

The low average IQ of Blacks in Sub-Saharan Africa is often met with incredulity. Among whites, almost everyone with an IQ of 75 is also retarded, but among groups with lower average IQs this association no longer holds. The reason is that mental retardation describes both an inability to solve problems (what IQ measures) and an inability to perform everyday tasks (e.g. daily living skills, communication skills, and social skills). Many whites with very low IQ have a genetic disorder (e.g., Down syndrome), whereas that level of reasoning ability is nearer to the average for sub-Saharan Africans. Jensen (1998) describes this phenomenon at length, including his great surprise at finding that people with normal social skills can perform so poorly on tests of fluid reasoning.

An IQ of 70 is often associated with mental retardation, but deficits in adaptive behavior, such as telling the time, interacting socially, and looking after oneself, have only limited correlation with IQ, and are more important than IQ in determining whether a person is able to live an independent life (Template:AYref, p. 177). Template:AYref reported that on the basis of IQ alone 10 times as many Blacks as Whites would be classified as retarded, but when adaptive behavior measures are added to the criterion, this difference completely disappears. Some ethnic differences in cognitive ability appear in some aspects of cognitive ability and not others (see below; Template:AYref, p. 178). The Black-White disparity seen in IQ does not appear in some basic cognitive functions that don't involve more than minimal elaboration, transformation, or other mental manipulation (Template:AYref, p. 178; Template:AYref).

Hybrid vigor

Intelligence is associated with the degree of "hybrid vigor" (heterosis) manifested by offspring of cross-ethnic matings. Children of Japanese–Caucasian cross-ethnic matings score .26 SD higher on several cognitive tests than those from within-ethnic matings, despite having virtually identical parental educational and occupational backgrounds. The increase in scores tends to be higher on cognitive tests that are more g-loaded, suggesting that hybrid vigor improves g. Heterosis may be partially responsible for the Flynn effect.

Explanations

Main article: Race and intelligence (Explanations)

Introduction

File:TBC-BW-IQ-SES-withDiff.png

According to a 1995 report released by the American Psychological Association, the black-white score gap "is not eliminated when groups or individuals are matched for SES". They write that "the living conditions of children result in part from the accomplishments of their parents: if the skills measured by psychometric tests actually matter for those accomplishments, intelligence is affecting SES rather than the other way around." The report concludes that no "simple income- and education-based index can adequately describe the situation of African Americans". A recent 1996 study using multiple socio-economic factors have accounted for 80% of the gap, and suggest that any remaining gap is statistically insignificant.

Most intelligence researchers believe that IQ differences among individuals reflect the general intelligence factor, g. The nature of g itself is still an active area of research, and the question of whether IQ differences among groups are substantially genetic is hotly contested.

According to the American Psychological Association, the difference between the average IQ scores of Blacks and Whites in the U.S. cannot be attributed to any obvious biases in test construction or cultural biases, as opposed to more occult environmental or genetic causes. Evidence against test construction and cultural bias includes the internal consistency of item difficulty for all groups, the equivalent validity of tests in predicting academic and occupational outcomes for all groups, and the persistence of the IQ gap on relatively culture-free tests.

Although IQ differences between individuals is highly heritable, this does not mean that average IQ differences between racial groups are necessarily genetic in origin, because estimates of heritability depend on the range of environments tested. High heritability by itself is not informative about group differences, so any inferences made from within group heritability will depend on additional considerations. However, many scholars agree that no considerations of heritabilty are sufficient if group differences are caused by environmental factors that uniquely and uniformly affect all members of one group but not another.

Environmental explanations

Regarding the IQ gaps in the U.S., there are numerous possible explanations beside genetics. One author lists more than a hundred. It has been suggested that African-American culture disfavors academic achievement and fosters an environment that is damaging to IQ. Likewise, it is argued that the persistence of negative racial stereotypes reinforces this effect. John Ogbu has developed a hypothesis that the condition of being a "caste-like minority" affects motivation and achievement, depressing IQ.

Arguing that IQ tests are often wrongly described as measuring "innate" rather than developed ability, Template:AYref conclude that this "labeling bias" causes people to inappropriately attribute the Black-White gap to "innate" differences. They assert that non-cultural environmental factors cause gaps measured by the tests, rather than any possible innate difference based on genetics, and to use these tests as a measure of innate difference is misleading and improper.

Estimates of the significance of genetics vs. environment are dependent on the strength of environmental factors. For example, schizophrenia, regarded as being highly heritable, has seen increased rates in second and third generation immigrants to Western European countries which do not seem to be the result of increased genetic susceptibility, but another, as yet unidentified, environmental factor(s) that seems to have become more influential.

Culture

Many anthropologists have argued that intelligence is a cultural category; some cultures emphasize speed and competition more than others, for example. Speculations about innate differences in intelligence between ethnic groups have occurred throughout history. Aristotle in the 4th century B.C. and Cicero in the 1st. century B.C. disparaged the intelligence of the northern Europeans of the time, as did the Moors in Iberia in the 11th century.

Health

Main article: Health and intelligence

In the developing world there are are many factors can greatly decrease IQ scores. Examples include nutrition deficiencies in iodine and iron; certain diseases like malaria; unregulated toxic industrial substances like lead and mercury; and poor health care for pregnant women and infants. Also in the developed world there are many biological factors that can affect IQ. Increased rates of low birth weight babies and lower rates of breastfeeding in Blacks as compared to Whites are some factors of many that have been proposed to affect the IQ gap.

The Flynn effect

File:James Flynn.jpg

James R. Flynn discovered the Flynn effect, that average IQ scores are increasing worldwide.

Main article: Flynn effect

The secular, international increase in test scores, commonly called the Flynn effect, is seen by Flynn and others as reason to expect the eventual convergence of average black and white IQ scores. Flynn argues that the average IQ scores in several countries have increased about 3 points per decade during the 20th century, which he and others attribute predominantly to environmental causes. This means, given the same test, the mean black American performance today could be higher than the mean white American performance in 1920, though the gains causing this appear to have occurred predominantly in the lower half of the IQ distribution. If changes in environment can cause changes in IQ over time, they argue, then contemporary differences between groups could also be due to an unknown environmental factor. On the supposition that the effect started earlier for whites, because their social and economical conditions began to improve earlier than did those of blacks, they anticipate that the IQ gap among races might change in the future or is even now changing. An added complication to this hypothesis is the question of whether the secular IQ gains can be predominantly a real change in cognitive ability. Flynn's face-value answer to this question is "No", and other researchers have found reason to concur. Responding to such concerns, Template:AYref have proposed a solution which rests on genotype-environment correlation, hypothesizing that small initial differences in environment cause feedback effects which magnify into large IQ differences. Such differences would need to develop before age 3, when the black-white IQ gap can be first detected.

Stereotype threat

Main article: Stereotype threat

Stereotype threat is the fear that one's behavior will confirm an existing stereotype of a group with which one identifies. This fear may in turn lead to an impairment of performance (Aronson, Wilson, & Akert, 2005). Stereotype threat was first articulated and documented by the social psychologists Claude Steele, Joshua Aronson, and Steven Spencer, who have conducted several studies on this topic.

It is suggested that reduced performance from "stereotype threat" could be a contributing factor to the gaps in IQ test scores. Template:AYref found that making race salient when taking a test of cognitive ability negatively affected high-ability African American students. Template:AYref point out that these findings are widely misinterpreted to mean that eliminating stereotype threat eliminated the Black-White performance gap.

Other Factors

Many studies that attempt to test for heritability find results that do not support the genetic hypothesis. They include studies on IQ and skin color, self-reported European ancestry, children in post WWII Germany born to black and white American soldiers, blood groups, and mixed-race children born to either a black or a white mother. Many intervention and adoption studies also find results that do not support the genetic hypothesis. Non-hereditarians have argued that these are direct tests of the genetic hypothesis and of more value than indirect variables, such as skull size and reaction time. Hereditarians argue that these studies are flawed due to their age, lack of replication, problems with their sample population, or that they do in fact support the genetic hypothesis.

Template:AYref, with data from "the first large, nationally representative sample" of its kind, report finding only a very small racial difference when measuring mental function for children aged eight to twelve months, and that even these differences disappear when including a "limited set of controls". They argue that their report poses "a substantial challenge to the simplest, most direct, and most often articulated genetic stories regarding racial differences in mental function." They conclude that "to the extent that there are any genetically-driven racial differences in intelligence, these gaps must either emerge after the age of one, or operate along dimensions not captured by this early test of mental cognition."

Another recent theory hypothesizes that fluid cognition (gF') may be separable from general intelligence, and that gF' may be very susceptible to environmental factors, in particular early childhood stress. Some IQ tests, especially those used with children, are poor measures of gF', which means that the effect of the environment on intelligence regarding racial differences, the Flynn effect, early childhood intervention, and life outcomes may have been underestimated in many studies. The article has received numerous peer commentaries for and against.

Genetic explanation

See also: Inheritance of intelligence

File:Jensen2.jpg

The contemporary debate can be traced to psychologist Arthur Jensen in 1969.

Arthur Jensen and others have concluded that the US IQ gap is partially genetic. Rushton and Jensen say that while plausible environmental explanation for the lower mean IQ in Blacks in the U.S. can be offered in many cases, these explanations are less capable of explaining the higher average IQ of East Asians than Whites.

To support their theory, they often cite several arguments and observations:

1. Black–White–East Asian differences in IQ, reaction time, and brain size are observed worldwide in a range of cultures and environments. In the United States, significant Black-White IQ differences are observable at every age above 3 years, within every occupation or socioeconomic level tested, in every region of the country, and at every time since the invention of ability tests.
2. Jensen and others have argued that the magnitude of race differences on different IQ subtests correlate with the extent to which those subtests measures g, which also correlates with measures of the subtests heritability. From these and other findings, they argue that race differences have a partly biological basis.
3. The rising heritability of IQ with age (within all races; studies have found on average in the developed world heritability starts at 20% in infants, rises to 40% in middle childhood, and peaks at 80% in adulthood); and studies showing the virtual disappearance (~0.0) by adulthood of shared environmental effects on IQ (for example, family income, education, and home environment), with adopted siblings partaking in the studies no more similar in IQ than with strangers From these studies, they argue that most suggested environmental explanations for IQ difference between groups do not have a strong enough effect on IQ to fully account for group differences.
4. Studies of US comparisons of both parents to children and siblings to each other finding regression to differing means for different races (85 for Blacks and 100 for Whites) across the entire range of IQs, despite the fact that siblings are matched for shared environment and genetic heritage, with regression unaffected by family socioeconomic status and generation examined

Template:A(Y)ref believe that the best explanation is that 50%-80% of the group differences in average US IQ is genetic.

Other evidence, such as transracial adoption, certain racial admixture studies, behavior genetic modeling of group differences, "life-history" traits, and evolutionary explanations have also been proposed to indicate a genetic contribution to the IQ gaps and explain how these arose.. Critics of this view, such as Robert Sternberg, argue that these studies are either flawed and thus inconclusive, or else that they support a primarily environment (<20% genetic) hypothesis. For example, Template:AYref argue that the statistical methods linking the Black-White gap to g are insufficient.

Surveys of academic opinion

A survey was conducted in 1987 of a broad sample of 1,020 scholars in specialties that would give them reason to be knowledgeable about IQ (but not necessarily about race). The survey was given to members of the American Education Research Association, National Council on Measurement in Education, American Psychological Association, American Sociological Association, Behavior Genetics Association, and Cognitive Science Society. According to the report, regarding the question "The source of black-white difference in IQ":

This is perhaps the central question in the IQ controversy. Respondents were asked to express their opinion of the role of genetic differences in the black-white IQ differential. Forty-five percent believe the difference to be a product of both genetic and environmental variation, compared to only 15% who feel the difference is entirely due to environmental variation. Twenty-four percent of experts do not believe there are sufficient data to support any reasonable opinion, and 14% did not respond to the question. Eight experts (1%) indicate a belief in an entirely genetic determination.

Robert Sternberg cautioned against supposing that the survey represented anything but opinion saying, "science isn't done by majority rule". Respondents on average called themselves slightly left of center politically, but political and social opinions accounted for less than 10% of the variation in responses. Carol Swain, author of The New White Nationalism reacted with some dismay to the survey, stating:

At least one important survey suggests that a belief in the biological inferiority of some races in regard to intelligence is more common than generally supposed. Smith College professor Stanley Rothman and Harvard researcher Mark Snyderman surveyed a sample of mostly scientific experts in the field of educational psychology in the late 1980s and found that 53 percent believed IQ differences between whites and African Americans were at least partly genetic in origin, while only 17 percent attributed the IQ differences to environmental factors alone (the remainder either believed the data was currently insufficient to decide the issue or refused to answer the question).

According to the American Psychological Association's 1995 task force report on intelligence research:

It is sometimes suggested that the Black/White differential in psychometric intelligence is partly due to genetic differences (Jensen, 1972). There is not much direct evidence on this point, but what little there is fails to support the genetic hypothesis.

The APA subsequently published eleven critical responses in 1997, most arguing that the report failed to examine adequately the evidence for the genetic hypothesis. Charles Murray, for instance, responded:

Actually, there is no direct evidence at all, just a wide variety of indirect evidence, almost all of which the task force chose to ignore.

The report did agree with many of the non-race-based statements on intelligence made in The Bell Curve and concludes with a call for more reflection in debates on intelligence and for a "shared and sustained effort" in more research to answer the many unanswered questions that remain. Coming advances in genetics and genomics are expected to soon provide the ability to test hypotheses about group differences more rigorously than has as yet been possible.

Researchers who believe that there is no significant genetic contribution to race differences in intelligence include Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, and Template:AYref. Some scientists who emphasize cultural explanations do not necessarily exclude a small genetic influence. Template:A(Y)ref suggests up to 20% genetic influence be included in the cultural explanation. Researchers who believe that there are significant genetic contributions to race differences in intelligence include Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, and Template:AYref.

sub-article content

The most common view among intelligence researchers is that IQ differences among individuals of the same race reflect (1) real, (2) functionally/socially significant, and (3) substantially genetic differences in the general intelligence factor. Similarly, average IQ differences among races reflect (1) real and (2) significant differences in the same g factor. However, it is a matter of debate whether IQ differences among races in a given country are primarily environmental or partly genetic.

A recent review summarizing the arguments for a "partly-genetic" explanation can be found here. A critique can be found here.

Test bias

It has been suggested that IQ tests may be biased against minorities, and that this accounts for part or all of the IQ gap. Some claim that there is no evidence for test bias. IQ tests are equally good predictors of IQ-related factors (such as school performance) for U.S. Blacks and Whites. The performance differences persist in tests and testing situations in which care has been taken to eliminate bias. It has also been suggested that IQ tests are formulated in such a way as to disadvantage minorities. Controlled studies have shown that test construction does not substantially contribute to the IQ gap. Studies have shown that the race of the test administrator does not have an effect on the U.S. Black-White gap (Template:AYref).

The lack of test bias due to test construction or methodology is widely accepted in the research community. From the American Psychological Association's summary of their 1996 task force report, "Intelligence: Knowns and Unknowns": "The differential between the mean intelligence test scores of Blacks and Whites does not result from any obvious biases in test construction and administration, nor does it simply reflect differences in socio-economic status" (Template:AYref). From The Wall Street Journal: Mainstream Science on Intelligence (PDF): "Intelligence tests are not culturally biased against American Blacks or other native-born, English-speaking people in the U.S. Rather, IQ scores predict equally accurately for all such Americans, regardless of race or social class."

This does not mean that anyone is claiming that there is no bias in the tests whatsoever. Somewhat but not directly related to the idea of cultural bias, is the concept of "labeling bias", described by Jencks and Phillips (1998). They insist that there exists a labeling bias in the tests, stating that most psychologists agree that IQ tests measure developed ability rather than innate ability—although the tests supposedly measure innate ability. Their assertion is that non-cultural environmental factors cause gaps measured by the tests, rather than any possible innate difference based on genetics, and to use these tests as a measure of innate difference is misleading and improper. In a PBS interview, Jencks states, "If we change the names of the tests, they still measure the same thing but it wouldn't convey this idea that somehow you've gotten the potential of somebody when you measured their IQ. And I think that creates a big bias, because the people who do badly on the tests are labeled as people with low potential in many people's minds and they sometimes even believe that about themselves."

Since the U.S. Supreme Court outlawed employee selection, including testing, which is "fair in form, but discriminatory in operation" (Griggs v. Duke Power Co., 1971; see this page on disparate impact), American companies have had a strong incentive to construct valid tests which do not produce an IQ gap between ethnic groups, called "selection bias" in employment. Despite this incentive, these efforts have generally failed. For example, in one case regarding a police selection test in Nassau County, New York, a scandal ensued when tests which showed no "selection bias" (Black-White score gap) were found to have been denuded of their ability to measure intelligence (Template:AYref, pp. 24-26 PDF).

While the existence of average IQ test score differences has been a matter of accepted fact for decades, during the 1960s and 1970s a great deal of controversy existed among scholars over the question of whether these score differences reflected real differences in cognitive ability. The critics of testing argued that IQ tests are predominantly measures of cultural variables, and that these variables have nothing to do with intelligence, but they do differ between racial-ethnic and socio-economic groups. If the culture of one group prevents them from developing the skills and abilities that IQ tests measure, then that group is culturally disadvantaged. In contrast, if people from different cultures score differently despite possessing the relevant skills and abilities to the same extent, then the IQ test is culturally biased.

Cultural bias can be distinguished from cultural disadvantage. To do this, a precise definition of bias is required. Bias as mean differences merely begs the question. IQ tests must be standardized against a representative sample of people, and so one suggestion was bias as improper standardization. This has been ruled out in part because re-standardization does not affect the IQ gap. Bias as content could exist if test items presuppose knowledge that is more common in one group. This has been ruled out in part because test item difficulty levels are nearly identical for Blacks and Whites. Arguably the most important condition is bias as differential predictive validity. If test scores predict performance on some other criteria (e.g., school grades) less well for one group than another, then the test shows differential validity. IQ tests have equivalent predictive validity for Blacks and Whites across a range of criteria (Template:AYref). Other kinds of bias have been proposed, but none have been found. Of these, bias as motivation is the most difficult to resolve because empirical tests are difficult. It is argued that Blacks are less motivated than Whites to perform well on IQ tests, but if equally motivated the IQ score gap would disappear. At least two views exist on the question of motivation. One view is that intelligence is an abstract concept related to potential, and the possibility of motivation affecting IQ scores is a problem. The second and more common view is that intelligence is a behavior, and performance is more relevant than potential. Under this view, the equal predictive validity of IQ for Blacks and Whites implies that IQ tests are right to be sensitive to motivation if motivation affects performance in important life outcomes.

Motivation

One environmental source of the IQ gap which has been suggested is poor motivation among low scorers. This hypothesis has been disputed by the researcher Arthur Jensen (1998). For example, one such test asks the subject to lift a finger from a depressed button to strike a light when it flashes. When more than one light is offered as a target the task involves a decision of which to hit (i.e. the one which is lit). These tests measure both reaction time (from when the bulb illuminates to when the subject lifts their finger) and movement time (from when the subject lifts their finger to when the subject reaches the bulb). While movement time measurements show no difference, reaction time measurements negatively correlate with IQ scores and show the same performance gaps between races (Template:AYref; Template:AYref). Jensen argues that it is difficult to imagine that people could be motivated during one part of each segment of the test but not motivated during the other, although no correlation between movement speed and intelligence is claimed. The correlation between IQ and reaction time is low (from .20 to .40).

Socio-economic factors

File:TBC-BW-IQ-SES-withDiff.png

Jensen asserts that the Black-White gap is higher at higher levels of socioeconomic status. (Template:AYref, p. 469).

IQ is correlated with economic factors. Blacks and Hispanics suffer poorer economic conditions than Whites. It has been suggested that the effects of poverty are responsible for some or all of the IQ gap. However, in the American Psychological Association report Template:A(Y)ref argue that economics cannot be the whole explanation. First, see the discussion in "Shared and nonshared environmental effects" below. Second, to the moderate extent that IQ and income are related, it appears that IQ determines income, and not the other way around (Template:AYref). (Note there are many other potential environmental factors beside income.) Third, there are gaps in IQ scores that are slightly smaller but still persist for individuals with similar family income and parental education.

Work by Template:A(Y)ref on average Black-Hispanic-White differences in IQ, education, and income casts doubt on conventional explanations of Black-White differences:

Hispanic children start with cognitive and noncognitive deficits similar to those of black children. They also grow up in similarly disadvantaged environments and are likely to attend schools of similar quality. Hispanics complete much less schooling than blacks. Nevertheless, the ability growth by years of schooling is much higher for Hispanics than for blacks. By the time they reach adulthood, Hispanics have significantly higher test scores than do blacks. Conditional on test scores, there is no evidence of an important Hispanic-white wage gap. Our analysis of the Hispanic data illuminates the traditional study of black-white differences and casts doubt on many conventional explanations of these differences because they do not apply to Hispanics, who also suffer from many of the same disadvantages. The failure of the Hispanic-white gap to widen with schooling or age casts doubt on the claim that poor schools and bad neighborhoods are the reasons for the slow growth rate of black test scores.

Researchers have found that many American Blacks and Hispanics are not given sufficient opportunity to learn language and thinking skills during the first three years of life, possibly due to economic status. The first three years are especially critical years for neural development of the brain, and previous studies have shown that when human children were deprived of most or all language skills at an early age, they never developed the ability to master language at a later age; if they only mastered a small amount of language and thinking skills at a young age, then they could only make small improvements in later years. A recent study has shown that many American Blacks and Hispanics are raised in homes where their parents speak relatively few sentences, and the sentences usually show only simple grammar. As a result, their children never hear millions of words during the time when their brains are developing linguistic skills. Without this linguistic input during their developing years, many are observed to quickly fall behind, and they can never catch up. Children in poorer welfare families, which includes a higher percentage of many minority populations, apparently hear up to 30 million fewer words by age three than children in higher income, usually White, families. (Source: The Early Catastrophe: The 30 Million Word Gap by Age 3)

Cultural explanations

Many anthropologists have argued that intelligence is a cultural category; some cultures emphasize speed and competition more than others, for example. During WWI African-Americans from the north tested higher than those from the south. This could be because African-Americans in the north had received more formal education (see Race: Science and Politics, written by Ruth Benedict in 1940). Thousands of ethnographic studies indicate that innate capacities for cultural evolution are equal among all human populations. The American Anthropological Association has endorsed a statement deriding all studies of race and intelligence .

Speculations about innate differences in intelligence between ethnic groups have occurred throughout history. Aristotle in the 4th century B.C. and Cicero in the 1rst. century B.C. disparaged the intelligence of the northern Europeans of the time, as did the Moors in Iberia in the 11th century.

It has been suggested that Black culture disfavors academic achievement and fosters an environment that is damaging to IQ (Template:AYref). Likewise, it is argued that a persistence of racism reinforces this negative effect. John Ogbu has developed a hypothesis that the condition of being a "caste-like minority" affects motivation and achievement, depressing IQ. However, Arthur Jensen has criticized these arguments on the grounds that they cannot explain the higher scores of East Indians and East Asians. Even proponents of the view that the IQ gap is caused partly by genetic differences, such as Arthur Jensen, recognize that non-genetic factors are likely involved. Indeed, one author has compiled a list of over one hundred possible causes of the Black-White IQ gap. These include the following:

• lack of reading material in the home
• poor cultural amenities in the home
• weak structural integrity of the home
• foreign language in the home
• low preschool attendance
• no encyclopedia in the home
• low level of parental education
• little time spent on homework
• low parental educational desires for child
• low parental interest in school work
• negative child self-concept (self-esteem)
• low child interest in school and reading

However, such factors have not been found to have an effect on IQ that lasts to adulthood among members of the same race (see below).

Cultural explanations for the IQ deficit among Blacks and Hispanics compared to Whites and East Asian minorities are complemented – and sometimes challenged – by the observation that East Asian minorities score well on IQ tests and on average enjoy greater economic success than other minorities. Along these lines, East Asians are sometimes referred to as "model minorities". East Asian and Jewish populations have suffered past discrimination and persecution which some argue is evidence against the importance of discrimination for IQ differences. While the severe discrimination against Jews and East Asians have today diminished, many argue that discrimination continue against blacks and that this is impacting the IQ scores of Blacks.

Language

Some argue that the higher IQ test scores in East Asian nations are in part attributed to some IQ tests' inherent bias towards testing spatial reasoning. They argue that logographic writing systems, like those used by Chinese and Japanese, develop spatial reasoning better than the alphabetic writing systems prevalent in Europe and America, though there are no studies that support this hypothesis. The same reasoning has been used to explain why students from some Asian countries (e.g., Singapore) tend to score better than average in tests of mathematics. Some argue that the East Asian advantage can also be explained by more rigorous education programs. However, even though few native-born Asian Americans learn to read and write Chinese characters, their performance is above-average on IQ tests.

A direct comparative test between Greek and Chinese students showed no difference in IQ or g, contradicting earlier studies which do not take the finer architecture of mental processing into account. The Chinese did outperform the Greeks in visuo/spatial ability, but this difference was smaller at earlier ages, grew during the first years of schooling and decreased later. The authors suggest that this pattern can be explained as follows: the Chinese students train their visuo/spatial ability during their early school years, as they have to learn many characters of the Chinese writing system. Later in life, the Greek students adopt compensating strategies to deal with visuo/spatial information, and therefore the difference decreases in this realm.

The Flynn effect

The Flynn effect consists of large documented worldwide increases in IQ scores for at least several decades. Attempted explanations have included improved nutrition, a trend towards smaller families, better education, greater environmental complexity, and heterosis.

The secular, international increase in test scores, commonly called the Flynn effect, is seen by Flynn and others as reason to expect the eventual convergence of average Black and White IQ scores. As demonstrated by Flynn, the average IQ scores in several countries have increased about 3 points per decade during the 20th century, which he and others attribute predominantly to environmental causes. This means, given the same test, the mean Black American performance today could be higher than the mean White American performance in 1920, though the gains causing this appear to have occurred predominantly in the lower half of the IQ distribution. If changes in environment can cause such large changes in IQ over time, they argue, then contemporary differences between groups could also be due to an unknown environmental factor. On the supposition that the effect started earlier for Whites, because their social and economical conditions began to improve earlier than did those of Blacks, they anticipate that the IQ gap among races might change in the future or is even now changing. An added complication to this hypothesis is the question of whether the secular IQ gains can be predominantly a change in real intelligence. Flynn's face-value answer to this question is "No", and other researchers have found reason to concur. Responding to such concerns, Template:AYref have proposed a solution which rests on genotype-environment correlation, hypothesizing that small initial differences in environment cause feedback effects which magnify into large IQ differences. Such differences would need to develop before age 3, when the Black-White IQ gap can be first detected.

Comparing the Flynn effect (IQ differences within races over time) to contemporary IQ differences between races is contested; for example, one report concludes "the nature of the Flynn effect is qualitatively different from the nature of black-white differences in the United States," and that "the implications of the Flynn effect for black-white differences appear small" (Template:AYref).

A recent theory hypothesizes that fluid cognition (gF') may be separable from general intelligence, and that gF' may be very susceptible to environmental factors, in particular early childhood stress. Some IQ tests, especially those used with children, are poor measures of gF', which means that the effect of the environment on intelligence regarding racial differences, the Flynn effect, early childhood intervention, and life outcomes may have been underestimated in many studies. The article has received numerous peer commentaries for and against.

A recent, newly available, large, and nationally representative data set find only very small (0.06 SD between whites and blacks) racial differences on measures for mental function for children aged eight to twelve months. These differences disappear when controlling for a limited set of factors such as differences in SES. "These findings pose a substantial challenge to the simplest, most direct, and most often articulated genetic stories regarding racial differences in mental function." "To the extent that there are any genetically-driven racial differences in intelligence, these gaps must either emerge after the age of one, or operate along dimensions not captured by this early test of mental cognition."

Nongenetic biological factors

Other researchers have come across what they see as additional reasons for the IQ gap. The paper Poverty and Brain Development in Early Childhood holds that there is a large amount of neural damage in many American Black and Hispanic children due to inadequate nutrition, substance abuse of the children's parents, a high incidence of maternal depression, exposure to environmental toxins, psychological trauma, and the neural effects of physical abuse. Template:A(Y)ref has proposed a "neurotoxity hypothesis" where pre- and post-natal exposure to heavy metal poisons differentially impacts Blacks. Drug abuse during pregnancy (e.g., alcohol and phenobarbital) can negatively affect IQ.

Infant mortality may be an indicator of environmental conditions that are sublethal but damaging to health. The rate of infant mortality in the U.S. Black population is twice that of the White population, which in turn is twice the rate of infant mortality among Asians. The rates of low birth weight (LBW), defined as less than 5.5 pounds, are correlated with infant death. LBW is different than premature birth; LBW can occur in full-term babies. LBW babies are at risk for many developmental, behavioral and cognitive abnormalities, including mental retardation. LBW (and premature birth) affect Blacks at twice the overall rate for the U.S. population. Mother's age is the strongest predictor of LBW, where teenagers are especially susceptible. Most of the Black-White differences in LBW are not account for by other environmental variables such as socioeconomic status, poverty status, mother's age, and education; but differential prenatal care explains some of the gap (Template:AYref). Thus, the cause of the Black-White gap in LBW is a mystery. Environmental intervention has strong but short-lasting effects on IQ among LBW babies (Template:AYref). Studies of LBW Black and White babies matched for birth weight and gestational age still find a one standard deviation IQ gap (Template:AYref).

A study of LBW babies indicates that breastfeeding can significantly improve their IQ scores tested at 8 years old (Template:AYref). After controlling for possible confounding factors, an improvement of 8.3 IQ points was found in the breastfed group as compared to the formula fed group. Black mothers are known to breastfeed infants less and for a shorter time than White mothers (Template:AYref; Template:AYref). Studies have shown IQ gains lasting into adulthood with increased duration of breastfeeding. Several recent studies shows that the intake of certain micronutrients, like those present in breast milk or fish oil, affects IQ scores even in developed nations. Template:A(Y)ref have shown larger head size at birth and higher IQ scores at 4 years of age when mothers took fish oil supplements during pregnancy and lactation. Template:A(Y)ref believes that dietary supplementation is a promising avenue of research for raising Black children's levels of g. Template:A(Y)ref has proposed a nutritional hypothesis for the Flynn effect.

Genetics

Part of the gap may well be genetic; there is no a priori reason to believe that every ethnic group or race has precisely the same distribution of genes that affect intelligence; a small amount of random variation early in human evolution may have later crystallized into differences seen today. Also there might have been smaller evolutionary pressure towards greater intelligence in some environments. The partly genetic hypothesis is often ignored or disregarded in primary research on group differences. It has been studied by researchers doing meta-analyses that combine multiple sources of primary materials, although such meta-analyses have been harshly criticized..

Arthur Jensen and others have concluded that the Black-White IQ gap is partly genetic. That is, they argue that the same mix of genetic and environment factors that cause IQ differences among individuals or between families of the same race also causes the differences seen between races. In this view, the genetic contribution to average intelligence differences among races are like average skin color differences: a product of different allelic frequencies within each population. Others are critical of Jensen's methods and evaluation (Template:AYref; Template:AYref; Template:AYref).

The results of most (indirect) analyses used to test the genetic hypothesis do not logically contradict a primarily environmental explanation of the lower IQ of Blacks. That is, a plausible (but some argue ad hoc) environmental explanation for the lower mean IQ in Blacks can be offered in most cases.

Shared and nonshared environmental effects

see also IQ: genetics vs environment

The heritability of intelligence within groups is high. It is widely recognized that within-group heritability does not in itself indicate that between-group differences are genetic in origin, although it is likely a necessary condition. Different kinds of evidence are needed to address the question of between-group heritability. As Herrnstein and Murray explain in The Bell Curve:

As we discussed in Chapter 4, scholars accept that IQ is substantially heritable, somewhere between 40 and 80 percent, meaning that much of the observed variation in IQ is genetic. And yet this tells us nothing for sure about the origin of the differences between races in measured intelligence. This point is so basic, and so commonly misunderstood, that it deserves emphasis: That a trait is genetically transmitted in individuals does not mean that group differences in that trait are also genetic in origin. Anyone who doubts this assertion may take two handfuls of genetically identical seed corn and plant one handful in Iowa, the other in the Mojave Desert, and let nature (i.e., the environment) take its course. The seeds will grow in Iowa, not in the Mojave, and the result will have nothing to do with genetic differences. (Template:AYref, p. 298.)

In most studies, measured heritabilities for intelligence are the same for Blacks as for Whites. A review by Template:AYref found some evidence suggesting lower heritability in Blacks than Whites (e.g., Template:AYref), but a larger body of evidence suggested equal heritabilities for both races. An analysis of the Georgia Twin Study by Template:AYref found equal heritabilities for both Blacks and Whites.

Two kinds of environmental effects can be distinguished: shared and nonshared effects (see nature versus nurture). Twin and adoption studies, used to measure heritability, can also be used to quantify the two types of environmental effects (Template:AYref). Shared environmental effects are due to factors experienced in common by all children raised in the same family but that differ among families. Examples of shared environmental effects include socio-economic factors, family cultural practices, and parental influences on children. Nonshared effects are unique for each child, and thus differ among families. Examples include chance events such as accidents, illness, and childhood friends. Anything that happens to one sibling and not to the other contributes to nonshared effects.

Template:A(Y)ref found (among a population of people studied in the U.S.) that the nonshared environmental effects on IQ remain approximately constant throughout life. Shared environmental effects in their study remained approximately constant (40% to 30%) from 4 to 20 years of age but then drop to zero in adulthood. Genetic factors increase throughout development (from 40% to 50%) but especially after 20 years of age (from 50% to 80%). Template:A(Y)ref corroborates these results. Environmental factors usually proposed to explain the Black-White gap are shared effects (e.g. social class, religion, cultural practices, father absence, and parenting styles). Template:A(Y)ref argues that because these effects account for little variance within a race, they are unlikely to account for the differences among races in developed nations.

However, others studies do support that shared environmental factors in developed nations can affect IQ, including IQ gains lasting into adulthood (Capron and Duyme, 1989). However, many such studies measure IQ in children (those shared effects that have disappeared in studies don't disappear until adulthood) or, some critics claim, do not have the controls needed to differentiate genetic and environmental effects. Others argue that some IQ gains disappear exactly because the interventions cease, continuing interventions like Head Start have showed that the IQ gains then remain.

In a re-analysis of adoption data from Template:AYref, Template:AYref found that the IQ gains that result from being adopted into high socioeconomic-status homes do not produce gains in g, but only in non-g factors. Jensen also found that the g factor scores of the adopted children reflected the socioeconomic level of their biological parents, not their adopted parents. This is consistent with Jensen's theory that g is the predominant genetic component of IQ scores; see Spearman's hypothesis below from the relationship between g and racial difference in IQ.

The recent paper Socioeconomic status modifies heritability of IQ in young children finds that the role of the environment is more important in poorer families. "The models suggest that in impoverished families, 60% of the variance in IQ is accounted for by the shared environment, and the contribution of genes is close to zero; in affluent families, the result is almost exactly the reverse." This suggests that the role of shared environmental factors may have been underestimated in older studies which often only studied affluent middle class families.

Only shared environmental effects captured in heritability studies disappear in adulthood; more extreme environmental deprivation may likely have a lasting impact on IQ in adults. Heritability only tells us what is the contribution of genes to variation in a trait, not what it could be (Template:AYref). Thus, heritability measures in the U.S. population cannot be extrapolated to populations in developing nations.

Spearman's hypothesis

Individual differences in the general intelligence factor, g, and its various biological correlates (e.g., the volume of gray matter in the frontal cortex) are partly caused by genetic differences between individuals. g has the highest measured heritability of any cognitive ability factor. Jensen formulated a hypothesis now referred to as Spearman's hypothesis which states that the degree of difference between black and white cognitive test scores will be correlated with the degree to which the test measures g (called the test's g-loading). Spearman's hypothesis has a strong form, which says that all test-score differences can be traced to g, and a weak form, which claims that some but not all differences are due to g.

Jensen found that black-white cognitive test score differences and test g-loadings correlate with a correlation coefficient of 0.6 (Template:AYref), and concluded that the weak form of Spearman's hypothesis was thus confirmed. Jensen's study combined scores on 149 psychometric tests obtained from 15 independent samples totaling 43,892 Blacks and 243,009 Whites (Template:AYref). Template:AYref have reanalyzed the data from several previous studies (Template:AYref; Template:AYref) that used the statistical method invented by Jensen (the method of correlated vectors) with a more recent and improved method (multigroup confirmatory factor analysis). "On the basis of the present, as well as other results (Dolan, 2000), we are convinced that the Spearman correlation cannot be used to demonstrate the importance of g in b-w differences with any confidence." and "It is possible that the analysis of all available data sets (perhaps using an appropriate meta-analytic procedure) will demonstrate that a model incorporating the weak version of Spearman's hypothesis provides the best description of the data. However, until this work is undertaken, we cannot accept Spearman's hypothesis as an "empirically established fact" This leaves the validity of Spearman's hypothesis, considered a central justification for the genetic explanation, an unresolved question.

Gene-environment interactions

Minority-specific effects on intelligence arising from cultural background differences between the races would be expected to affect the correlations between the measures of environmental background variables and outcome measures. Rowe et al. (1994) compared cross-sectional correlation matrices using both independent variables (e.g., home environment, peer characteristics) and developmental outcomes (e.g., achievement, delinquency). Template:A(Y)ref compared correlations between academic achievement and family environment. They found that the covariance matrix of each group were equal. That is, they failed to find evidence for distortions in the correlations between the background variables and the outcome measures that would suggest a minority-specific developmental factor. Similarly, Template:A(Y)ref, Template:A(Y)ref, and Template:A(Y)ref, Template:A(Y)ref, Template:A(Y)ref) found nearly identical statistical structure on psychometric variables in each group. The factor structure of cognitive ability is nearly identical for Blacks and for Whites; there were no race-specific factors.

Using structural equation modeling Template:A(Y)ref estimated the genetic architecture for Black and White siblings. They found that the best-fitting model for the source of differences between and within races was the same: both genetic and environmental factors. Template:AYref (p. 465) reanalyzed a subset of this data. This analysis found that the Black-White IQ difference was best explained by a model of both genetic and environmental factors, and that the genetic-only and the environmental-only models were inadequate.

Template:A(Y)ref using differential heritabilities among Blacks and Whites and later Template:A(Y)ref using inbreeding depression calculated in Japan found that the Black-White gap is least on IQ subtests most affected by the environment, and greatest on subtests that are least affected by the environment. It is difficult to attribute the relationship between inbreeding depression from Japan with the Black-White IQ gap in the U.S. to an environmental (not-genetic) cause.

Rushton's application of r-K theory

Main article: Race, Evolution and Behavior

In his controversial 1995 work Race, Evolution and Behavior, J. Philippe Rushton argued that racial differences in IQ, as well as a number of other racial differences, could be explained by r/K selection theory, where one evolutionary strategy favors reproduction potential over other strengths (r-selection) and one favors traits that are highly adaptive in a stable environment (K-selection). Rushton claims that humans are extremely K-selected, and that it was less extreme (there was more r-selection) in the African environment than elsewhere. He posits that the comparatively cold and harsh environment of Europe caused the evolution of those who migrated there slightly more to a K-selected pattern than those who remained in Africa, and the even harsher environment of Northeastern Asia forced the evolution of East Asians to an even higher level of K-selective behavior. This theory has been severely criticized.

Richard Lynn has developed similar theories and argues that the ice age that took place in East Asia from about 28,000 to 12,000 years ago acted as a selection force on East Asians to increase intelligence by requiring the building of shelter, making clothes, and making fires, and selected especially strongly for spatial skills such as those needed to hunt large prey and build the tools necessary to do so. (Template:AYref). Template:A(Y)ref has cited the fact that the order in Blacks, Whites, and East Asians appeared is the same as the order of their respective brain sizes as additional evidence. This theory, however, has difficulty explaining why Native Americans, who appeared even later and emigrated from the northernmost parts of Asia, do not currently have high scores on IQ tests. On the other hand, Template:A(Y)ref argues that lower scores of Native Americans can be attributed to the evolutionary relaxation of cognitive demands due to the more temperate environment and comparative ease with which North American fauna could be hunted. But it can be argued that life along the fertile river plains in China was not particularly harsh. It is also questionable that conditions in deserts are no less harsh but people living there do not currently score high on IQ tests.

The theory is directly contradicted by the only comparative study on IQ scores in different European nations that showed a statistically insignificant association between the average IQ and latitude of various European nations. In contrast, Template:AYref (p. 309) found a correlation of 0.62 (p=0.00001) between latitude and cranial capacity in samples worldwide and reported that each degree of latitude was associated with an increase of 2.5 cm³ in cranial volume. A more recent study finds this pattern only when including a Siberian population living in extremely cold condition. The explanation may be natural selection for a thermoregulatory capacity in extremely cold environments, resulting in brachycephalization, rather than a selection for intelligence.

Rushton sources, such as s "semi-pornographic book" and the Penthouse magazine, have been dismissed by other researchers, or have been criticized as extremely biased and inadequate reviews of the literature, as misreporting the results, or as simply false. There have also been many other criticisms of the theory. More recent studies contradicts Rushton's claims. A meta-analysis shows that blacks are not more psychopathic, nor do they differ in from whites when testing for the big five personality traits, differences in sex hormones between whites and East Asians are best explained by environmental differences, and the fundamental prediction of the theory that blacks have a higher frequency of twins is incorrect. However, the rate of twin births in the US has doubled since 1971, the time of the study Rushton cited, due to older moms (for which twin births are naturally more common) and fertility treatments, both demographic characteristics that are more common among Whites.

Other evolutionary explanations for putative genetic differences

There are two mainstream theories of the evolution of contemporary humans. The single-origin hypothesis proposes that modern humans evolved in Africa and later replaced hominids in other parts of the world. The multiregional hypothesis proposes that modern humans evolved to some degree from independent hominid populations. An emerging synthesis theory proposes that the genes of contemporary human are predominantly descended from a recent African origin, but that interbreeding with other hominids may have contributed genes to local populations (Template:AYref). Template:A(Y)ref speculate that "as much as 80% of the nuclear genome is significantly affected by assimilation from archaic humans (i.e., 80% of loci may have some archaic admixture, not that the human genome is 80% archaic)."

Populations within continents are more closely related to one another than to populations on other continents (Template:AYref; Template:AYref; Template:AYref; Template:AYref). Thus, to the extent that racial labels correspond to ancient ancestry, racial groups (especially in the U.S.) are statistically distinguishable on the basis of genetics (Template:AYref).

The Imperial examination system in China and similar systems in other East Asians nations have been proposed as an explanation for the higher average IQ, compared for example with the caste system in India which made if much more difficult for the intelligent but poor to gain SES. Celibacy for priests have been invoked as an explanation for claimed lower IQ in Catholic countries, although this also seems to be contradicted by the equal IQ in northern and southern Europe. The earlier mentioned comparative European IQ study found that there was a larger variation in IQ scores in southern Europe. Possible explanations for the earlier mentioned difference for this include sample selection, larger environmental differences affecting IQ scores between urban and rural areas in southern Europe at the time of the test (1981), and/or that northern Europe became socially stratified later in history, causing less genetic variation in IQ.

Constant persecutions favoring a high IQ have been proposed as an explanation for the higher average Ashkenazi IQ, but other persecuted groups like the Romani do not score highly on IQ tests. Another theory suggests that there was selective breeding for Talmudic scholarship, but this seems unlikely to have been important because there weren't very many professional rabbis. A selective force that only affects a tiny fraction of the population can never be strong enough to cause important evolutionary change in tens of generations. A more plausible, but difficult to evaluate without detailed demographic information, variant of this is that achievement in Talmudic scholarship had high status and that rich families therefore preferred to marry their daughters to males who excelled in this. Yet another explanation, according to a 2005 study, the most likely, is that they mostly worked jobs in which increased IQ strongly favored economic success, in contrast with other populations, who were mostly peasant farmers. (See "Natural History of Ashkenazi Intelligence")

Comparisons of explanations

The possible explanations for observed differences in intelligence between racial groups generally occur along two axes - how valid a proxy race is for most genes that control intelligence, and primarily-genetic/primarily-environmental. Also complicating the picture is the implicit assumption, by some, of a natural ordering of the races, with blacks inferior to whites - this assumption leads to a false dichotomy between "genetic" and "environmental" explanations, since it is more than possible for an environmental explanation to account for more than the observed difference (it is not a zero-sum game).

	Race valid proxy	Race invalid proxy
Primarily-genetic	Races are useful categories for determining one's genetic background, and the majority of the differences in intelligence are determined by genetics. (Racialist/Hereditarian) This category includes people like J. Phillipe Rushton. The Black-White IQ gap in the U.S. is seen as a result of inferior Black genetics, and superior White genetics. Even if controlled for environmental factors, the gap would exist. Within Group Heritability (WGH) of intelligence is seen as having a genetic cause. Between Group Heritability (BGH) of intelligence is seen as having a genetic cause.	Races are not useful categories for determining one's genetic background, being inferior to clines on traits, and the majority of the differences in intelligence are determined by genetics. (Environmental) This category includes those who challenge the utility of "race", but believe in strong genetic contributions to intelligence. The Black-White IQ gap in the U.S. is seen as a statistical artifact, although individual-to-individual differences in intelligence may have a large genetic component. The gap would mostly disappear if proper controls on genetics were applied, although it would be replaced with an inferior genetics/superior genetics gap. Within Group Heritability (WGH) of intelligence is seen as having a genetic cause. Between Group Heritability (BGH) of intelligence is seen as a statistical artifact with non-genetic causes.
Primarily-environmental	Races are useful categories for determining one's genetic background, and the majority of the differences in intelligence are determined by environmental factors. (Environmental) This category includes those who believe race is a valid categorization for certain traits (skin color, certain genetic diseases), but believe that intelligence is a trait which varies primarily due to environment. The Black-White IQ gap in the U.S. is seen as a statistical artifact. The gap would mostly disappear if proper controls on environment were applied. Within Group Heritability (WGH) of intelligence is seen as having only a small genetic component. Between Group Heritability (BGH) of intelligence is seen as having only a small genetic component.	Races are not useful categories for determining one's genetic background, being inferior to clines on traits, and the majority of the differences in intelligence are determined by environmental factors. (Environmental) This category includes those who challenge the utility of "race", and believe that intelligence is a trait which varies primarily due to environment. The Black-White IQ gap in the U.S. is seen as a statistical artifact, along with all other Black-White differences. The gap would mostly disappear if proper controls on environment were applied. Within Group Heritabilty (WGH) of intelligence is seen as having only a small genetic component. Between Group Heritability (BGH) of intelligence is seen as a statistical artifact with non-genetic causes.

Detailed arguments regarding U.S. Black-White IQ gap

The Black-White IQ gap in the U.S. may be explained by a variety of causes. Some insist on a primarily genetic component with an implicit assumption that Blacks are genetically inferior to whites. Others accept a joint genetic/environmental model, with no assumptions about what "race" is inferior or superior. A great deal of criticism is also targeted towards the use of "race" as scientific category. Below are various arguments made by proponents of specific theories and conclusions.

primarily genetic	primarily environmental	joint genetic/environemntal	black inferior	racism/oppression
Utility of racial categories
Some geneticists argue categories of self-identified race/ethnicity or biogeographic ancestry are both valid and useful. They emphasize the continental origin of major races: “namely, African, Caucasian (Europe and Middle East), Asian, Pacific Islander”. For other groups "a decision to split or lump smaller populations into racial groups will depend on the focus of a research question." They find that these categories correspond with clusters inferred from multilocus genetic data.. Moreover, they conclude that this correspondence implies that genetic factors might contribute to unexplained phenotypic variation between groups. In the 1985 survey reported by Leiberman and colleagues, only 16% of biologists reject the concept of race. In response to claims such as "there are no human races," Ernst Mayr, one of the 20th century's leading evolutionary biologists, said "Those who subscribe to this opinion are obviously ignorant of modern biology." Risch and colleagues (2002) argue that "much of this discussion does not derive from an objective scientific perspective." In response to claims that race does not exist, geneticst A.W.F. Edwards quotes Fischer: "that the best causes tend to attract to their support the worst arguments, which seems to be equally true in the intellectual and in the moral sense."	Modern anthropologists use clines as an alternative to "races", with variation occurring gradually across geographic areas, instead of social constructs of "race". "By 1985 anthropology's core concept of "race" had been rejected by 41% of physical anthropologists and 55% of cultural anthropologists [Lieberman 1968; Lieberman, Stevenson, and Reynolds 1989:69]. A similar survey in 1999 found that the concept of race was rejected by 69% of physical anthropologists and 80% of cultural anthropologists (Lieberman and Kirk n.d.)" "As the 20th century reached its end, a paradox emerged in which, while most anthropologists had come to reject concepts of biological races and racism (Lieberman and Kirk n.d., Lieberman, Stevenson, and Reynolds 1989), a number of psychologists persisted in the “race” idea and the “scientific” racism that had prevailed in the 19th and much of the 20th century (Herrnstein and Murray 1994; Lynn 1977a, b; Rushton 1988b)." "During the last hundred years, the debate over the meaning of race has retained a highly consistent core, despite evolution of the technical details...Each time the technical facade of these racialist arguments is destroyed, the latest jargon and half-truths from the margins of science are used to rebuild them around the same core belief in Black inferiority. No technology—even the awe-inspiring tools now available to DNA science—can overcome the handicap of fundamental conceptual errors. Race is not a concept that emerged from within modern genetics; rather, it was imposed by history, and its meaning is inseparable from that cultural origin." "Race, a quantitative distinction within a species, has no equivalent defining criterion—that is, genetic variability is not restricted to discrete packages (American Anthropological Association [AAA], 1998). This aversion to distinctions without meaning is what has led most geneticists and anthropologists to the conclusion that race in its common usage has no biological basis (AAA, 1998; Darwin, 1871/1981; Gould, 1996; Graves, 2001; Kittles & Weiss, 2003; Lewontin, 2000; Mayr, 1996; Montagu, 1964; Templeton, 1998)." "This point bears restating: To cluster individual members of a species into groups is not the same as creating a natural biological category. One could cluster humans into an infinite number of fractal units based on size (family, clan, deme, continent, etc.) or on a physical trait (height), and the meaning of those groupings would vary in an infinite number of ways."
"This assertion is both counter-intuitive and factually incorrect.... If it were true, it would be impossible to create discrete clusters of humans (that end up corresponding to the major races).... Two Caucasians are more similar to each other genetically than a Caucasian and an Asian."	"Genetic data ... show that any two individuals within a particular population are as different genetically as any two people selected from any two populations in the world." "From the hereditarian perspective, why then would IQ not be expected to vary between, say, Sicilians and Swedes as much as between Europeans and Africans?"
IQ differences
	Assertions of Black-White-East Asian differences are based on invalid "aggregation" of data. The only nationwide IQ tests have been done in a few developed countries, and the few studies in other nations have been severely criticized, see IQ and the Wealth of Nations. editor note: make mention of the Flynn effect on so called "culture-fair" tests as Raven.		Black-White-East Asian differences in culture-fair and reaction-time IQ test scores exist world-wide despite international differences in social, cultural, and economic conditions. Template:AYref, among others, argues that higher IQ scores among East Asians (living in East and South Asia) than Whites (living in North American and Europe) is seen as a challenge for primarily environmental theories because standards of living in Asia are lower than or equal to those in North America or Europe. For example, average IQ scores are higher in the People's Republic of China (Template:AYref) than for African Americans even though per capita GDP (PPP) is lower in China ($5,000 as of 2003) than per capita African American income ($15,583 as of 2003) (Template:AYref).
Sub-Saharan Africans have an average IQ of 70 (Rushton 1996a), supported by data using Raven's Progressive Matrices. Template:A(Y)ref discusses his observation among California children that very low IQ Blacks are qualitatively normal in social and motor skills, but perform no better than Whites with equally low IQ on cognitive tasks except those that require rote memorization, where "mentally retarded" Blacks do significantly better than Whites. He speculates that 12.5% of cases of IQ <70 are due to organic defects in Blacks, compared to 50% in Whites, giving the impression that low IQ Whites are more handicapped than low IQ Blacks.	Such findings imply that half of all sub-Saharan Africans are mentally retarded, incapable of carrying out even simple daily tasks. One argument of many against the reliability of the IQ scores in developing nations is that some such countries a majority of the population would be classified by the IQ scores as mentally retarded. For example, Equatorial Guinea is one of the few African nations that actually have a study and is classified as having the lowest average IQ in the world, 59, based on study of 48 persons 10-14 years old. A large proportion of the population should also be classified as moderately (<16%) and severely (<2%) mentally retarded. In the U.S., the moderately mentally retarded require moderate supervision and the severely mentally retarded often have other physical disabilities and may thus require constant supervision, be unable to provide for themselves, be unable to speak long sentences, and, in many cases, be unable to do things like getting dressed without help.
Average IQ scores gaps within the U.S. and internationally have been stable since they were first measured in the early and mid 20th century (Template:AYref; see above), despite the Flynn effect. One statistical analysis suggests that the Flynn effect is qualitatively different than the Black-White IQ gap (Template:AYref).	Ulric Neisser (1997) has shown significant gains in scores on Raven's Progressive Matrices, suggesting as per the Flynn effect, substantial environmental influences are at work, not genes. One estimate is that the average IQ in the U.S. was below 75 before the Flynn effect started and it seems likely that the effect started earlier and may end sooner for Whites. Some studies show that the IQ gaps is decreasing in the US and even if they are not this may change in the future if the Flynn effect ends first for Whites. Lynn and Vanhanen only have IQ scores from 3 developing nations before 1950, in two of these only 1 study, make any claims of knowing average continental IQ strange indeed. The Wicherts study refers to "measurement invariance", is not a statement about the role of genetics in the B-W gap, and is a relatively minor statement that not mentioned in the abstract.
The Black-White IQ gap in the US has remained constant at approximately one standard deviation since it was first measured in the early 1900s despite social and economic change during that time, including the civil rights movement and Brown v. Board of Education. "A difference [of] at least [12 points] is found in virtually every comparison ever published of reasonable sized [White] and [Black] samples, at every age above 3 years, within every level of education, socioeconomic status, and occupation, in every region of the country, and at every time in history since mental ability tests were invented." Narrowing of the gaps in skill test scores does not indicate changes in g.	flynn 2006 Other studies show that the gap in the US is narrowing. For example, one large recent study found much smaller differences than earlier studies in math and reading skills in young children and found that all of the remaining differences could be explained by a few environmental factors. Moreover, the extent of concrete social and economic change is debatable; for example, Jonathan Kozol, in his 2005 book Shame of the Nation, found that public schools are more racially segregated today than they were in 1969. editor note: make clear the selective qualifications of comparisons avoid data sets that contradict Jensen
American Blacks have a lower average IQ than Hispanic and Native American groups, which are more socio-economically deprived. For example, the Inuit, who live in the Arctic, have higher average IQs than North American Blacks (Template:AYref; Template:AYref) despite being extremely poor (Template:AYref; Template:AYref).	That Blacks are less socioeconomically deprived than Hispanics or Native Americans in the US is controversial. The Inuit cannot be directly compared to the US population, for example they have substantially different nutrition from eating large amounts of fish.
g factor
"The g-based factor hierarchy is the most widely accepted current view of the structure of abilities" Correlations between an IQ subtest's g-loading, and the magnitude of the Black-White-East Asian score gap for that subtest (Template:AYref; Template:AYref pp. 47-8; Template:AYref pp. 138-9). For example, the Black-White gap is greater on backward digits span (a test where subjects repeat digits in the reverse order that they are given, and the more g-loaded test) than forward digits span (a test where subjects repeat digits in the same order that they are given, and the less g-loaded test). As predicted by Spearman's hypothesis, the B-W gap is largest on the most g-loaded tests. Narrowing of the B-W gap has been seen mostly on less g-loaded tests, such as literacy tests. Arthur Jensen argues that there is no independent evidence that the environmental explanations commonly given for the Black-White gap (for example, "past history of slavery", discrimination, "caste status", "peer pressure against 'acting white'", etc) have an effect on g (Template:AYref, p. 510).	g-loading and the method of correlated vectors, the statistical method used in many older studies, has been criticized heavily in recent research. The author of multiple factor analysis, L. L. Thurstone (1947), warned "we must guard against the simple, but common, error of merely taking a first centroid factor, a first principal component, or other mean factor, in a test battery and then calling it a general factor". "Spearman's g, then, is a "statistical artifact." (C. Loring Brace, 2001)
Correlations between an IQ subtest's heritability or inbreeding depression and the magnitude of the Black-White-East Asian score gap for that subtest (Template:AYref). Environmental theories would predict the opposite.	What subtest are most heritable and how to measure this is debated. Racialist hereditarians make assertions regarding the heritability of traits such as intelligence, to imply that a) group differences are genetic and b) intelligence is a fixed ability. As per Nature Reviews Neuroscience: "The issue of race is not unique to biological investigations of intelligence, but it is more visceral in a biological context (in part because heritability can be misunderstood to imply both that group differences must be genetic and that intelligence is a fixed rather than a context-sensitive ability — both of these interpretations are incorrect)." "The view that a trait is independently heritable (or heritable at all) simply because it can be separately defined and analyzed has been rendered largely obsolete by modern developments in biology" [Thorogood 1997; Lovejoy, Cohn, and White 1999:13247)
Theories holding that Blacks score lower than Whites because of test bias would predict the Black-White gap would be smaller on culture-reduced tests than on culture-loaded tests. Yet the reverse is true (Template:AYref).	?
Brain size differences
editor note: this is the original entry on brain size Black-White-East Asian differences in IQ, reaction time, brain size and other physiological variables (such as skull structure, and degree of convolution of the brain) in the United States and a few other developed countries (e.g. UK, Japan). Larger brain size and higher IQ of East Asians than Whites is seen as a challenge for the primarily environmental theory. ----- Race correlates with cranial measurements (Rushton, 1990:786). ----- Skull sizes of different races have been compared since the 1800s (Morton, 1849), showing differential sizes which are assumed related to IQ (Rushton, 1996). editor note: merge with brain size discussion below	editor note: make note of critiques of Rushton's B-W-EA aggregation methodology - evidence of differences challenged The gaps may be explained by many other factors except genetics (see above). Differences among some White groups are as large as the difference between Whites and Blacks in the US. Many racial groups show great variation when tested at different times and in different places, indicating large environmental influences. The IQ scores and larger brain size of East Asians have numerous possible explanations, e.g. many East Asian nations have a very high consumption of fish. One study has shown larger head size at birth and higher IQ scores at 4 years of age when the mothers took fish oil supplement during pregnancy and lactation. ----- The study cited by Rushton (Beals, Smith, and Dodd 1984) actually finds that climate variables are strongly correlated with cranial variation, where as "race" had low correlations. ----- The views of Morton and Rushton have been invalidated "by a century of anthropological research" (Gossett 1965, Cravens, 1978), and themselves are inconsistent with each other (Morton putting "Caucasoids" as the group with the largest brains, and Rushton putting "Mongoloids" as the group with the largest brains).
In a meta-analysis of 37 studies, Template:AYref concluded that total brain size correlates with intelligence. Among adults of the same sex, the average correlation is approximately 0.4. The correlation between brain size and IQ seems to hold for comparisons between and within families (Gignac et al. 2003; Jensen 1994; Jensen & Johnson 1994). However, one study found no such family-related connection (Schoenemann et al. 2000). The volume of specific brain structures also correlates with IQ. Genetics are known to influence brain structure (Template:AYref) and some aspects of cognition (Template:AYref). In one study, the correlation between gray matter volume and g is found to be mediated entirely by genetic factors (Template:AYref). A review in Nature Reviews Neuroscience noted "Correlations between intelligence and total brain volume or grey matter volume have been replicated in magnetic resonance imaging (MRI) studies, to the extent that intelligence is now commonly used as a confounding variable in morphometric studies of disease." editor note: correlation of brain size to intelligence may be necessary for the racialist-hereditarian view, but is not proof of its validity	In modern humans, intraspecific correlation between brain size and various measures of "intelligence" is nonexistent (Henneberg 1998). "What we do know is that within human families, brain size does not predict general cognitive ability; nongenetic events play a significant role in brain volume and cognitive ability associations (Schoenemann et al. 2000)." (Fatimah Jackson 2001)
Correlates of IQ
The three-way differences in the IQ and SAT scores of children persists even after controlling for parental income or education, which seems to counter arguments that the gap is due to socioeconomic conditions. In addition, some researchers have argued from studies in siblings that IQ affects socioeconomic status, rather than the other way around (Template:AYref). Studies which simultaneously control for dozens of social and economic conditions are uninformative because they assume that such differences are the cause rather than the consequence of IQ differences (Template:AYref; Template:AYref). SAT scores correlate with IQ as well as scores from one IQ test correlate with another (Template:AYref. Neisser et al. concluded "it is clear that no model in which 'SES' directly determines 'IQ' will do."	Adjustments for socioeconomic conditions almost completely eliminate differences in IQ scores between black and white children. The remaining difference is statistically insignificant. SAT scores are not the same as IQ scores.
According to Arthur Jensen, environment-only explanations would predict a decreasing Black-White gap with increasing socioeconomic status of parents. Yet the opposite is true (Template:AYref, p. 469).	?
Three-way differences in reaction times have been demonstrated (Template:AYref; Template:AYref; Template:AYref; Template:AYref), and it is difficult to explain differences in reaction time through lack of motivation or cultural differences on the part of the subjects. Reaction times correlate with g (Template:AYref).	Differences in reaction time or brain volume may be caused by environmental factors. As noted, there have been large changes in cranial vault size and shape during the last century in the US for both Black and Whites, far beyond what can be explained genetically. In addition, reaction time and brain size have only a low correlation with IQ test scores and are not shown to have any real-world significance.
Causes of individual differences in IQ
Rising heritability of IQ with age, and decreasing shared-family effects (e.g., socioeconomic factors) on IQ after adolescence. An environmental cause of the IQ gap is seen as necessarily being a shared family effect.	High within-group heritability does not logically exclude the all environmental interpretation. Racialist hereditarians make assertions regarding the heritability of traits such as intelligence, to imply that a) group differences are genetic and b) intelligence is a fixed ability. As per Nature Reviews Neuroscience: "The issue of race is not unique to biological investigations of intelligence, but it is more visceral in a biological context (in part because heritability can be misunderstood to imply both that group differences must be genetic and that intelligence is a fixed rather than a context-sensitive ability — both of these interpretations are incorrect)." "The view that a trait is independently heritable (or heritable at all) simply because it can be separately defined and analyzed has been rendered largely obsolete by modern developments in biology" [Thorogood 1997; Lovejoy, Cohn, and White 1999:13247)
Studies using structural equation modeling find results consistent with the partially-genetic explanation (Template:AYref, pp. 464-467). Studies suggesting that IQ heritability and gene-environment interactions within races are the same for Blacks and Whites. That is, no race-specific statistical factors, such as an effect of White racism, have been identified in such analyses. The IQ gap exists even among middle- and upper-class Black and White families where within-race heritabilities are high and shared family effects are near zero.	Many factors that can affect IQ differ between Blacks and whites, for example duration of breastfeeding or poverty. Many older studies have only studied middle class families but SES has recently been shown to be relatively more important in poorer families.
The finding that when Black and White children are matched for IQ, their siblings tend to have IQs that regress towards different means (85 for Blacks and 100 for Whites). For example, among Black and White children matched with an IQ of 120, the siblings of the Black children have an average IQ of 100 whereas the siblings of the White children have an average IQ of 110. This is a stronger test of the party-genetic hypothesis than regression from parents to offspring because siblings share a similar environment (Template:AYref). This is a novel prediction of the partly genetic hypothesis.	Regression towards the mean only shows that mean IQ scores are different which is not a new finding. That is not evidence that the cause of this difference is genetic.
The three-way difference in average IQ can be measured in very young children and before the start of schooling. For example, a one standard deviation gap is observed in Black and White 3-year olds matched for gender, birth order, and maternal education (Template:AYref). Template:AYref found that by age 6 the average IQ of East Asian children is 107, 103 for White children and 89 for Black children. Template:A(Y)ref found that the same trichotomy in brain size and IQ held at 4 months, 1 year, and 7 years of age.	Environmental factors can affect very young children, for example nutrition by the mother during pregnancy and breastfeeding. More breastfeeding gives IQ gains and the duration of this is known to differ between White and Black mothers. Two studies in Chile shows that nutritional status affects IQ, scholastic achievement, and brain volume.
Adoption and admixture
Average Black-White-East Asian differences in IQ (both positive and negative) remain following transracial adoption. Three studies of East Asian children adopted by White families reported average IQ scores in the adopted East Asian children that are as high or higher than Whites, despite the fact that some of the children in the studies had suffered some forms of preadoptive deprivation or malnutrition and associated developmental delays (Template:AYref; Template:AYref; Template:AYref). Template:A(Y)ref found Black-White-East Asian differences in cognitive and psychological variables among adolescents adopted by white families. They also found that Black-White mixed-race children fell in between the White and Black averages. See also the Minnesota Transracial Adoption Study.	Existing adoption studies lack behavior genetic controls needed to distinguish between genetic and environmental effects. Several other adoption studies finds no IQ difference between Whites and East Asians.
Template:AYref argue that these studies are "peculiarly old, the mean year of publication being 1960" and "actually very weak and nondecisive, not having been replicated even once". No studies of Black-White genetic admixture have been performed with the multi-locus DNA sequencing required to make reliable conclusions. Lynn (2002) reports that skin color is corrlated with intelligence among African Americans.	IQ have very low positive to low negative correlation with Whiteness of skin, degree of European blood groups, or self-reported degree of European ancestry among Blacks.{{cn})
Template:AYref points out that while the study of children born in post-WWII Germany finds no difference between white and interracial children, it does find a large difference in IQ between boys and girls, suggesting that sampling artifacts have affected the results. No studies that make use of proper behavior genetic techniques have been able to identify environmental factors to explain the IQ gap.	A study which showed near-disappearance of the black-white gap among children of black and white servicemen raised by German mothers after World War II. Some, like the American Psychological Association, consider this study be strong evidence against the genetic explanation.
High achieving minorities
Theories holding that Blacks score lower than Whites because of test bias would predict that Asians would also score lower than Whites. However, the reverse is true.	Assuming that test bias must negatively affect scores of any minority group is unsupportable. Asians and Blacks do not share the same environmental or cultural influences.
Ashkenazi Jews have often been persecuted and discriminated against, but they still display the highest average IQ of any ethnic group, as well as SAT scores higher than those of non-Jewish Caucasians. Template:AYref, pp. 67-68 argues that this counters arguments that depressed IQ scores of African Americans are due to discrimination or prejudice. Similarly, Template:AYref, p. 510, points to the examples of Chinese, Japanese, Jews, and East Indians, stating that they have been minorities, discriminated against, or even persecuted, yet do not do poorly on g-loaded tests. Template:AYref make similar arguments.	Persecution and discrimination is not always applied in identical ways with identical effects. Conflating the terms "discrimination" and "prejudice" as having both the same meaning as well as effect is a logical fallacy. Neither do persecution and discrimination encompass the entirety of culture or environmental effects. Rowe is particularly criticized for "misuse of broad scientific concepts and incorrect or biased misinterpretation of specific scientific data."
Template:AYref argues that environmental explanations cannot explain why East Asians score higher on tests of spatial reasoning than verbal reasoning.	Dichotomy in intelligence is entirely compatible with an all environmental explanation but may not be with the g theory. East Asians may have higher spatial ability for example due to their knowledge of iconographic languages.
A similar dichotomy in spatial/nonspatial intelligence test scores is present in both East Asians and several Native American and Inuit populations (Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref Template:AYref).	?
Significance and evolution of races
A relationship between times of evolutionary emergence and brain sizes for East Asians, Whites, and Blacks. (Template:AYref)	?
Racial differences in biological characteristics such as myopia that correlate with g. Myopia is more common in Asians and Jews than in Whites, and more common in Whites than in Blacks. Myopia is about twice as common in Jews than in Gentiles. Myopia is likely pleiotropic with g (i.e., myopia and g are caused by the same genes). Arthur Jensen argues that this supports the partially-genetic explanation. (Template:AYref, p. 487-489)	?
Partly-genetic theory is predicated on a model that the IQ gap has (the genetic) part of its origin in human evolution. Thus, it predicts that the Black-White-East Asian differences in average IQ, reaction-time, and brain size should be accompanied by a similar pattern of differences in other inherited traits. Proponents cite three-way average differences such as personality, maturation, and reproductive traits as support of this prediction; Template:AYref, p. 273, cite a "matrix of 60 life-history traits". Research on racial differences in twining and testis size was the subject of a review by author and scientist Jared Diamond (1986) in the journal Nature, in which he investigated correlations between possible racial variations in testicular size and hormone levels and found one small study suggesting that dead Danish men on autopsy have larger testicles than dead Chinese men. Some studies also suggested lower hormone levels and frequency of twins among Asians than Africans. Template:A(Y)ref has additionally pointed to the Black-White-East Asian gradient in average hip size, arguing that nothing can explain this phenomenon except the need to give birth to children with different brain sizes.	Differences may have environmental causes and may be unrelated to one another. Many of these claims of differences have been shown to be false, for example references to scientific literature with respects to racial differences in sexual characteristics turned out to be references to a nonscientific semipornographic book and to an article in the Penthouse Forum. Regarding Jared's study, he notes that smaller testicle size among Koreans was not associated with a lower frequency of sexual intercourse, which directly contradicts Rushton rK-theory. There is only an insignificant difference in frequency of twins between Whites and Blacks in the U.S (34.8 vs 34.7), also contradicting the theory. Higher frequency of twins in certain African populations can be explained by large scale consumption of Yam which in rats produces such results.
Other statistical racial differences have been reported to exist. this is a repeat of the last entry - merge	Other statistical racial differences have been found to be artifacts of poor controls. David and Collins (1997) studied birth weight and race correlations between black and white Americans. Although the correlations still held when controlled for socioeconomic variables, when they considered African immigrants to the United States, the racial pattern vanished (African-born immigrants clustered with American whites, not American blacks). "The low-birth-weight phenomenon appears to be not an endowment of the black gene pool but a consequence of the experience of growing up black in America" (Jonathan Marks, 2001)
Rushton asserts a "principle of aggregation" which derives his conclusions from a vast array of historical data.	The poor quality of data cited by racialist-hereditarians is strongly criticized, and all of their citations of persistent patterns are seen as unsupportable once proper controls are added and obviously invalid data is filtered out.
"Mongoloids" have superior, larger brains because in their evolution they had to "adapt to a cognitively demanding but predictable cold Pleistocene climate (Rushton, 1997) editor note: the last entry in the table covers evolutionary explanations	"the mode of subsistence of all human populations was essentially the same over the past 200,000 years. This was conditioned by adaptation to the selective pressure engendered by the cultural ecological niche. For these reasons, then, cognitive capabilities should . . . be the same in all the living populations of the world" (Brace 1998:112).

Other interpretations

The two most widely-known works concerning race and intelligence are The Mismeasure of Man by Stephen Jay Gould, originally published in 1981, and The Bell Curve by Richard Herrnstein and Charles Murray, published in 1994. Media controversy surrounding The Bell Curve motivated Gould to revise and expand The Mismeasure of Man to respond to arguments from The Bell Curve, publishing the book's second edition in 1996. Many current researchers think that both books are outdated due to new research.

A recent paper in the Psychological Review, "Heritability Estimates Versus Large Environmental Effects: The IQ Paradox Resolved" by William T. Dickens of The Brookings Institution and James R. Flynn presents a mechanism by which environmental effects on IQ may be magnified by feedback effects. This work may provide a resolution of the contradiction between the viewpoint of The Bell Curve's authors and the 'nurture' effects observed by others. A latter paper responded to objections.

For additional relevant discussion, see: http://www.skeptic.com/eskeptic/05-02-18.html Two book reviews, by Paul R. Gross and Alondra Oubre, of Sarich’s and Miele’s book, Race: The Reality of Human Differences.

Some cite research that they believe indicates that discriminated or lower-status minorities do tend to have lower IQ, some without apparent genetic differences. Like Blacks and Hispanics in the U.S., minorities in some societies show achievement gaps (such as the Maori in New Zealand, aboriginals in Australia, scheduled castes ("untouchables") in India, non-European Jews in Israel, and the Burakumin in Japan). The most prominent finding cited is that Northern Irish Catholics used to score about 15 points lower than Protestants. Similarly, Irish, Italian and Polish immigrants in the U.S. are reported to have all scored about 80 in the beginning of the 19th century, but now tend to reach 100. The same is true of persons from rural versus urban areas in general (see e.g., this article by conservative columnist and economist Thomas Sowell and this page on European and Greek IQ. More arguments of the kind are to be found here).

Opinions of scholars and others

A survey was conducted in 1987 of a broad sample of 1,020 scholars (65% replied) in specialties that would give them reason to be knowledgeable about IQ (but not necessarily about race; Snyderman & Rothman, 1987). The survey was given to members of the American Education Research Association, National Council on Measurement in Education, American Psychological Association, American Sociological Association, Behavior Genetics Association, and Cognitive Science Society. Political and social opinions, reported in the same survey, accounted for less than 10% of the variation in responses. (Respondents on average called themselves slightly left of center politically.) Measures of expertise or eminence accounted for little or no variation in responses.

One question was "Which of the following best characterizes your opinion of the heritability of the Black-White difference in I.Q.?" (emphasis original). The responses were divided into five categories:

• The difference is entirely due to environmental variation: 15%.
• The difference is entirely due to genetic variation: 1% (8 respondents).
• The difference is a product of both genetic and environmental variation: 45%.
• The data are insufficient to support any reasonable opinion: 24%.
• No response (or not qualified): 14%.

A selection of survey results

Question	Responses
What heritability would you estimate for IQ differences within the White population?	Average estimate of 60 (± 17) percent.
What heritability would you estimate for IQ differences within the Black population?	Average estimate of 57 (± 18) percent.
Are intelligence tests biased against Blacks?	On a scale of 1 (not at all or insignificantly) to 4 (extremely), mean response of 2 (somewhat).
What is the source of the average Black-White difference in IQ?	Both genetic and environmental (45%, or 52% of those responding).

The age of the survey and the anonymity of the respondents could constrain its interpretation.

In a 1988 survey, journalists, editors, and IQ experts were asked their "opinion of the source of the black-white difference in IQ" Template:AYref

Group	Entirely Environment	Entirely Genetic	Both	Data Are Insufficient
Journalists	34%	1%	27%	38%
Editors	47%	2%	23%	28%
IQ Experts	17%	1%	53%	28%

The view of the American Psychological Association

In response to the controversy surrounding The Bell Curve, the American Psychological Association's Board of Scientific Affairs in 1995 established a special task force to publish an investigative report on the research presented in the book.

The task force agrees that there do exist large differences between the average IQ scores of blacks and whites, and that these differences cannot be attributed to biases in test construction, nor does it "simply reflect differences in socio-economic status". While they admit there is no empirical evidence supporting it, the APA task force suggests that explanations based on social status and cultural differences may be possible. Regarding genetic causes, they noted that there is not much direct evidence on this point, but what little there is fails to support the genetic hypothesis. The January 1997 issue of American Psychologist included eleven critical responses to the APA report, most of which criticized the report's failure to examine all of the evidence for or against the partly-genetic interpretation of racial differences in IQ.

Significance of group IQ differences

See also: Practical importance of IQ

Within societies

Scope

The distribution of IQ scores among individuals of each race overlap substantially. In a random sample of equal numbers of US Blacks and Whites, Template:A(Y)ref estimates most variance in IQ would be unrelated to race or social class. The average IQ difference between two randomly paired people from the U.S. population is approximately 17 points, and this only increases to 20 points when the pair are black and white. When the pair are siblings, the average difference is still 12 points.

In essays accompanying the publication of The Bell Curve, Herrnstein and Murray argue that whether the cause of the IQ gap is genetic or environmental does not really matter because that knowledge alone would not help to eliminate the gap and that knowledge should not impact the way that individuals treat one another. They argue that group differences in intelligence ought not to be treated as more important or threatening than individual differences, but suggest that one legacy of Black slavery has been to exacerbate race relations such that Blacks and Whites cannot be comfortable with group differences in IQ or any other traits.

Moreover, although it may appear paradoxical, it could be argued that an indirect outcome of social egalitarianism would be to raise the genetic contribution to intelligence to as high as possible, by minimizing environmental inequalities and any negatively IQ-impacting cultural and socio-economic differences. If all such inequalities could somehow be completely eliminated, any remaining group (but not individual) IQ differences would then be 100% hereditary: the only remaining factor that could potentially contribute to race-based outcome differences.

Practical importance

The appearance of a large practical importance for intelligence for some life outcomes makes some scholars claim that the source and meaning of the IQ gap is a pressing social concern. Template:AYref and Template:AYref argue that the IQ gap is reflected by gaps in the academic, economic, and social factors correlated with IQ. However, others dispute the general importance of the role of IQ for real-world outcomes, especially for differences in accumulated wealth and general economic inequality in a nation. One study found that wealth, race and schooling are important to the inheritance of economic status, but IQ is not a major contributor and the genetic transmission of IQ is even less important. (See "Practical importance of IQ".)

The effects of differences in mean IQ between groups (regardless if the cause is social or biological) are amplified by two statistical characteristics of IQ. First, there seem to be minimum statistical thresholds of IQ for many socially valued outcomes (for example, high school graduation and college admission). Second, because of the shape of the normal distribution, only about 16% of the population is at least one standard deviation above the mean. Thus, although the IQ distributions for Blacks and Whites are largely overlapping, different IQ thresholds can have a significant impact on the proportion of Blacks and Whites above and below a particular cut-off.

IQ Cohorts & Significance (U.S.)

IQ range	Whites	Blacks	Black:White ratio	Training prospects	High school dropout	Lives in poverty	"Middle-Class Values" index
<75	3.6%	18.0%	~5:1	simple, supervised work; eligible for government assistance	55%	30%	16%
75-90	18.3%	41.4%	~2:1	very explicit hands on training; IQ >80 for military training; no government assistance	35%	16%	30%
90-100	24.3%	24.9%	~1:1	mastery learning, hands on	6%	6%	50%
100-110	25.9%	11.9%	~1:2	written material plus experience
110-125	22.5%	3.6%	~1:6	college format	0.4%	3%	67%
>125	5.4%	0.2%	~1:32	independent, self-teaching	0%	2%	74%
Based on Wechsler Adult Intelligence Scale IQs for Whites (mean = 101.4, SD = 14.7) and for Blacks (mean = 86.9, SD = 13.0) from (Reynolds, Chastain, Kaufman, & McLean, 1987, p. 330). Training prospects from Template:AYref and Template:AYref. Significance data is from Template:AYref, and is based on Whites only. Results from the total population are nearly indistinguishable. Results for Blacks only are similar but not identical (see the table below for comparisons between groups). Note that these are merely correlations. For example, poverty could be both a cause and consequence of low IQ.

Small differences in IQ, while relatively unimportant at the level of an individual, could theoretically have large effects for the United States population as a whole. As a demonstration of these possible effects, Template:A(Y)ref used a resampling technique to argue that, all else equal, a simulated 3-point drop in average IQ had little effect on factors like marriage, divorce, or unemployment. However, their study found that a simulated drop in IQ from 100 to 97-points increased poverty rates by 11% and the proportion of children living in poverty by 13%. In the simulation, similar rises occurred in rates of children born to single mothers, men in jail, high school drop-out, and men prevented from working due to health-related problems. In contrast, when they simulated an increase in average IQ of 3-points to 103, they calculated that poverty rates fell 25%, children living in poverty fell 20%, and high school drop-out rates fell 28%.

Professors James Heckman and Nicholas Lemann, as well as several other scholars and scientists have the criticized validity and reliability of the data which led to the aforementioned findings by Template:A(Y)ref.

Controlling for IQ

Group Outcomes After Being Statistically Adjusted to Match IQ

Condition (matching IQ)	Black %	Latino %	White %
High school graduation (103)	93	91	89
College graduation (114)	68	49	50
High-level occupation (117)	26	16	10
Living in poverty (100)	11	9	6
Unemployed for 1 month or more (100)	15	11	11
Married by age 30 (100)	58	75	79
Unwed mother with children (100)	51	17	10
Has ever been on welfare (100)	30	15	12
Mothers in poverty receiving welfare (100)	74	54	56
Having a low birth-weight baby (100)	6	5	3
Average annual wage (100)	$25,001	$25,159	$25,546
Men ever incarcerated (100)	5	3	2
"Middle-Class Values" index (100)	32	45	48
from Herrnstein & Murray (1994), Chapter 14. Professors James Heckman and Nicholas Lemann, as well as several other scholars and scientists have criticized the validity and reliability of the data which led to this chart.

Because IQ correlates with a number of social and economic outcomes that have been found to differ between the black and white populations overall, The Bell Curve argues that the disparities in outcomes are due to group differences in IQ (See above chart).Professors James Heckman and Nicholas Lemann and others claim that its findings are based on data that is not completely valid and reliable.

According to Murray and Herrnsteins' Bell Curve, when IQ is statistically controlled for, the probability of having a college degree or working in a high-IQ occupation is higher for Blacks than Whites. Controlling for IQ shrinks the income gap from thousands to a few hundred dollars. Controlling for IQ cuts differential poverty by about three-quarters and unemployment differences by half. However, controlling for IQ has little effect on differential marriage rates. For many other factors, controlling for IQ eliminates the differences between Whites and Hispanics, but the Black-White gap remains (albeit smaller).

White populations are not homogeneous groups regarding real-world outcomes. For example, in the U.S. 33.6% of persons with self-reported Scottish ancestry completed college, while only 16.7% of persons with self-reported French-Canadian ancestry have done so.

For additional discussion of the effects of controlling for group differences on a variety of outcomes and groups, see Template:AYref, and Template:AYref.

Between nations

File:Discover Sept 1982.jpg

Richard Lynn's early research on Japanese IQ initiated an academic controversy and became part of Western countries' surprise in the early 1980s at the Japanese' unexpected economic and industrial achievements. (Discover 1982)[24]

Some people have attributed differential economic growth between nations to differences in the intelligence of their populations. One example is Richard Lynn's IQ and the Wealth of Nations. The book is sharply criticized in the peer-reviewed paper The Impact of National IQ on Income and Growth. Another peer-reviewed paper, Intelligence, Human Capital, and Economic Growth: An Extreme-Bounds Analysis, finds a strong connection between intelligence and economic growth. It has been argued that East Asian nations underachieve compared to IQ scores. One suggested explanation is that verbal IQ is more important than visuospatial IQ.

Jared Diamond's Guns, Germs and Steel instead argues that historical differences in economic and technological development for different areas can be explained by differences in geography (which affects factors like population density and spread of new technology) and differences in available crops and domesticatable animals. However, these environmental differences may operate in part by selecting for higher levels of IQ

For high-achieving minorities

The book World on Fire notes the existence in many nations of minorities that have created and control a disproportionate share of the economy, a market-dominant minority. Examples include Chinese in Southeast Asia; Indians in the United States and Britain; Whites, Indians, Lebanese and Igbo people of Western Africa; Whites in Latin America; and Jews in pre-World War II Europe, modern America, and modern Russia. These minorities are often resented and sometimes persecuted by the less successful majority.

In the United States, Jews, Asian Indians, Japanese, and Chinese earn incomes 1.72, 1.42, 1.32, and 1.12 times the American average, respectively. Jews and East Asians have higher rates of college attendance, greater educational attainment, and are many times overrepresented in the Ivy League and many of the United States' most prestigious schools, even though affirmative action discriminates against Asians in the admissions process (relative to Whites as well as to other minorities) At Harvard, for example, Asian American and Jewish students together make up 51% of the student body, though only constituting roughly 6% of the US population. In various Southeast Asian nations, Chinese control a majority of the wealth despite being a minority of the population and are resented by the majority, in some cases being the target of violence. Likewise, African immigrants to the US have the highest educational attainment rates of any immigrant group in the United States with higher levels of completion than the stereotyped Asian American model minority, raising further questions about the benefits of affirmative action programs based on race as well as stereotypes about the intellectual capacity of races.Despite the ongoing controversy about IQ difference in the US. Gargi Bhattacharyya , Liz Ison and Maud Blair have found that IQ differences between black and white populations in the UK and elsewhere are virtually non-existent. In fact, Blacks of African descents in the UK, on average, earn more money and obtain higher levels of education than the native white populations. According to the London Daily Times “Black Africans have emerged as the most highly educated members of British society, surpassing even the Chinese as the most academically successful ethnic minority.”

Areas	U.S. Population	All Immigrants	African Immigrants	Asian Americans	Europe, Russia & Canada	Latin, South America & Carribbean
Not Fluent in English	0.6%	30.5%	7.6%	23.4%	11.5%	44.0%
Less Than High School	17.1%	39.1%	12.1%	21.2%	23.5%	57.4%
College Degree	23.1%	23.3	43.8%	42.5%	28.9%	9.1%
Advanced Degree	2.6%	4.2	8.2%	6.8%	5.8%	1.9%

SOURCE: 2000 US CENSUS

Achievement in science, a high-complexity occupation in which practitioners tend to have IQs well above average, also appears consistent with some group IQ disparity. Only 0.25% of the world population is Jewish, but Jews make up an estimated 28% of Nobel prize winners in physics, chemistry, medicine, and economics. In the U.S., these numbers are 2% of the population and 40% of winners. Over half of the world chess champions from 1886 to 2000 had at least one Ashkenazi Jewish parent.

Some studies have shown significant variation in IQ subtest profiles between groups. In one analysis of IQ studies on Ashkenazi Jews, for example, high verbal and mathematical scores, but average or below average visuospatial scores were found. In a separate study, East Asians demonstrated high visuospatial scores, but slightly above average, average or slightly below average verbal scores. The professions in which these populations tend to be over-represented differ, and some believe the difference is directly related to IQ subtest score patterns asserted to exist. The high visiuospatial/average to below average verbal pattern of subtest scores has also been asserted to exist in fully assimilated third-generation Asian Americans, as well as in the Inuit and Native Americans (both of Asian origin).

Public debate and policy implications

Main articles: Race and intelligence (Public controversy), Race and intelligence (Accusations of bias), and Race and intelligence (Utility of research)

Media portrayal

Main article: Race and intelligence (Media portrayal)

See also: Acting white

Race and intelligence are sometimes portrayed as related in media. People of various races have been portrayed as more or less intelligent in media such as films, books, and newspapers. Likewise, reporting on research into race and intelligence has been criticized: either for giving scientific theories of race too much credit, or for rejecting the theories of some researchers in the name of racial harmony.

Critics of contemporary media have highlighted portrayals of minorities as less intelligent (or in the case of Asians, on occasion more intelligent) in films and movies. Entman and Rojeki assert that media images of Blacks may have profound effects on the perceptions by both Blacks and Whites about black intellectual potential.

Even so-called positive images of Black people can lead to stereotypes about intelligence. In Darwin's Athletes: how sport has damaged Black America and preserved the myth of race John Hoberman writes that the prominence of African-American athletes encourages a de-emphasis on academic achievement in black communities.Film director Spike Lee explains that these images have negative impacts "In my neighborhood, we looked up to athletes, guys who got the ladies, and intelligent people," said Lee. "[Now] If you're intelligent, you're called a white guy or girl."

Blacks are not the only ethic group in the US to be stereotyped as stupid. Shortly after the large waves of immigration in the 19th century and number of immigrant groups such as the Irish were stereotyped as being more closely related to apes or dogs and therefore intellectually inferior. This changed after the definition of "white" was expanded to include the Irish. Unlike other racial stereotypes of intelligence, the 19th century psudo-scientific ideas about of Irish stupidity and inferiority are not supported heriditarian proponents of modern race research. Other stereotypes, of Blacks, Jews and asians endure to this day.

media portrayal sub article content

Race and intelligence are sometimes portrayed as related in media. People of various races have been portrayed as more or less intelligent in media such as films, books, and newspapers. Likewise, reporting on research in to race and intelligence has been criticized: either for giving scientific theories of race too much credit, or for rejecting the theories of some researchers in the name of racial harmony.

Examples

Critics of contemporary media have highlighted portrayals of minorities as less intelligent (or in the case of Asians, on occasion more intelligent) in films and movies.

Early stereotypes

Early minstrel shows lampooned the supposed stupidity of Blacks. Detail from cover of The Celebrated Negro Melodies, as Sung by the Virginia Minstrels, 1843

Early minstrel shows lampooned the supposed stupidity of Blacks, movies such as Birth of a Nation questioned weather or not Black people were fit to run for governmental offices or vote. Secretary of State John C. Calhoun arguing for the extension of slavery in 1844 said "Here (scientific confirmation) is proof of the necessity of slavery. The African is incapable of self-care and sinks into lunacy under the burden of freedom. It is a mercy to give him the guardianship and protection from mental death."

Even after slavery ended the intellectual capacity of Black people was still frequently questioned. Lewis Terman wrote in The measurement of intelligence in 1916

"(Black and other ethnic minority children) are uneducable beyond the nearest rudiments of training. No amount of school instruction will ever make them intelligent voters or capable citizens in the sense of the world…their dullness seems to be racial, or at least inherent in the family stock from which they come…Children of this group should be segregated in special classes and be given instruction which is concrete and practical. They cannot master abstractions, but they can be made efficient workers…There is no possibility at present of convincing society that they should not be allowed to reproduce, although from a eugenic point of view they constitute a grave problem because of their unusual prolific breeding."

Modern stereotypes

See also: Acting white

Some regard Jar Jar as thinly veiled version of the type of portrayals used in minstrelsy to lampoon the supposed stupidity of Black people.

Contemporary sports commentators have questioned if blacks are intelligent enough to hold "strategic" positions or coach games such as football.

Patricia J. Williams, writer for The Nation said this of Jar Jar a character from the 2002 Star Wars film "...intentionally or not, Jar Jar's pratfalls and high jinks borrow heavily from the genre of minstrelsy. Despite the amphibian get-up, his relentless, panicky, manchild-like idiocy is imported directly from the days of Amos 'N' Andy." Many aspects of Jar Jar's character are believed to be highly reminiscent of the archetypes portrayed in blackface minstrelsy.In another example, a study of the portrayal of race, ethnicity and nationality in televised sporting events by journalist Derrick Jackson in 1989 showed that blacks were more likely than Whites to be described in demeaning intellectual terms.Political activist and one time presidential candidate Rev. Jesse Jackson said in 1985 that the news media portray blacks as less intelligent than we are. Film director Spike Lee explains that these images have negative impacts "In my neighborhood, we looked up to athletes, guys who got the ladies, and intelligent people," said Lee. "[Now] If you're intelligent, you're called a white guy or girl."

According to Robert M. Entman an Andrew Rojecki, authors of the The Black Image in the White Mind, in television and film Black characters are less likely to be the "the intellectual drivers of its problem solving." Entman and Rojeki assert that media images of Blacks may have profound effects on the perceptions by both Blacks and Whites about black intellectual potential.

Even so-called positive images of Black people can lead to stereotypes about intelligence. In Darwin's Athletes: how sport has damaged Black America and preserved the myth of race John Hoberman writes that the prominence of African-American athletes encourages a de-emphasis on academic achievement in black communities. Several other authors have said that sports coverage that highlights 'natural black athleticism' has the effect of suggesting white superiority in other areas, such as intelligence.

Asian stereotypes

File:The Doctor.jpg

Fu Manchu.

Asians have generally been portrayed in the media as intelligent but unsociable. The early 20th century fictional character Fu Manchu was one startling example of this kind of media portrayal:

Imagine a person, tall, lean and feline, high-shouldered, with a brow like Shakespeare and a face like Satan, a close-shaven skull, and long, magnetic eyes of the true cat-green. Invest him with all the cruel cunning of an entire Eastern race, accumulated in one giant intellect, with all the resources of science past and present... Imagine that awful being, and you have a mental picture of Dr. Fu-Manchu, the yellow peril incarnate in one man. –The Insidious Dr. Fu Manchu

White stereotypes

The social definition of "White" has changed over the years, and several White groups have at times been portrayed by the media as unintelligent. This includes ethnic groups such as the Polish, Irish, Italians and Slavs.

The Irish

See also: Stereotypes of Europeans/Whites

File:Irish-stereotypes.jpg

The cartoon below contrasts Florence Nightingale, the Civil War nurse, with "Bridget McBruiser", the stereotypical Irish woman.

Although "Irish" is seen as a nationally or ethnicity by most people today it was once viewed as a grouping on par with distinctions now made between races. An analysis of nineteenth-century attitudes by Mary J. Hickman and Bronwen Walter showed that the 'Irish Catholic' was one viewed as an "other" or a differnt race in the construction of the British nationalist myth.

In 19th centuray cartoons, Irish immigrants were shown as ape-like and as racially different. During this period of high levels of immigration, Americans were beginning to consider the theory of evolution. Scientists, such as James Redfield, argued that "facial angle" was a sign of intelligence and character. When they studied the "physiognomy" or facial structure, or Irishmen, they detected animalistic qualities. The fact that such caricatures of Irish people existed, and were once considered to be "scientifically accurate" shows how much racial definitions can change. Few people today think of Irish people as "not white"or "racially primitive."

Portrayal of research by the media

The Bell Curve

Main article: The Bell Curve

The Bell Curve is a controversial, best-selling 1994 book by Richard J. Herrnstein and Charles Murray exploring the role of intelligence in American life. The book became widely read and debated due to its discussion of race and intelligence in Chapters 13 and 14.

Press coverage has given considerable positive attention to theories of genetic racial differences in intelligence even though there is no consensus among researchers regarding their validity. Upon publication, The Bell Curve, a controversial book that asserted that the gap in black and white IQ scores was, in part, genetic, received a great deal of positive publicity, including cover stories in Newsweek ("the science behind [it] is overwhelmingly mainstream"), early publication (under protest by other writers and editors) by The New Republic by its editor-in-chief at the time Andrew Sullivan, and The New York Times Book Review (which suggested critics disliked its "appeal to sweet reason" and are "inclined to hang the defendants without a trial"). Early articles and editorials appeared in Time, The New York Times ("makes a strong case"), The New York Times Magazine, Forbes, the Wall Street Journal, and National Review. It received a respectful airing on such shows as Nightline, the MacNeil/Lehrer NewsHour, the McLaughlin Group, Think Tank, PrimeTime Live, and All Things Considered. [33]

The positive reception of The Bell Curve in media such as newspapers and television talk shows was troubling to critics such as economist Edward S. Herman and evolutionary biologist Joseph L. Graves who felt that it indicated a troubling acceptance of what Herman calls deterministic racist doctrines.

APA response

Main article: The Bell Curve

In response to the controversy surrounding The Bell Curve, the American Psychological Association's Board of Scientific Affairs in 1995 established a special task force to publish an investigative report on the research presented in the book. Intelligence: Knowns and Unknowns. Regarding genetic causes, they judged that there is not much direct evidence on this point, but what little there is fails to support the genetic hypothesis. The January 1997 issue of American Psychologist included eleven critical responses to the APA report, most of which criticized the report's failure to examine all of the evidence for or against the partly-genetic interpretation of racial differences in IQ.

Stereotype threat

Main article: Stereotype threat

Stereotype threat is the fear that one's behavior will confirm an existing stereotype of a group with which one identifies. This fear may in turn lead to an impairment of performance (Aronson, Wilson, & Akert, 2005). Stereotype threat was first articulated and documented by the social psychologists Claude Steele, Joshua Aronson, and Steven Spencer, who have conducted several studies on this topic.

While Stereotype threat has not received as much media attention as The Bell Curve much of the media coverage has been positive. The Atlantic Monthly ran a feature article on the topic authored by psychologist Claude M. Steele in August 1999. Still one conservative researcher feels that the coverage has been inaccurate. In a 2004 study Sackett said he found indications of widespread and systematic research misinterpretation regarding one of the more popular explanations for the IQ gap. Introducing stereotype threat to a test-taking environment has been shown to increase the existing gap between Blacks or Whites in relation to Whites or Asians respectively, and has thus been offered as a potential contributor to the gap. However Sackett said 88% of accounts in the popular media, 91% in scientific journals, and 67% in psychology textbooks had misinterpreted the findings as that eliminating the introduced stereotype threat eliminated the Black-White gap, when in fact the students had already been matched according to prior scores. Sackett suggests the appeal of the misinterpreted findings may have been a factor, and that such research results in general may in this way be systemically more readily accepted.

Snyderman and Rothman

Main article: Snyderman and Rothman (study)

The Snyderman and Rothman study accused the media of liberal bias in reporting on race and intelligence. Mark Snyderman who has written multiple articles for the conservative magazine National Review and Stanley Rothman who has written for National Review and Public Interest, a neoconservative magazine argued in their joint paper in 1988 that media coverage of intelligence-related research is often inaccurate and misleading. They surveyed the opinions of journalists and science editors and intelligence experts (not necessarily with knowledge about race), including scholars in the subfields of psychology, sociology, cognitive science, education, and genetics. They argue that media coverage of intelligence related topics was overall inaccurate and misleading. They say the media has misreported the views of the scientific community, especially about the role of genetic and environmental factors in explaining individual and group differences in IQ.

In their 1987 survey, they wrote:

Forty-five percent believe the difference to be a product of both genetic and environmental variation, compared to only 15% who feel the difference is entirely due to environmental variation. Twenty-four percent of experts do not believe there are sufficient data to support any reasonable opinion, and 14% did not respond to the question. Eight experts (1%) indicate a belief in an entirely genetic determination.

No poll option was provided to indicate "predominantly (but not entirely) environmental.

They found that the media regularly presented the views of Stephen Jay Gould and Leon Kamin as representative of mainstream opinion among experts, whereas those who stress that individual and group differences may be substantially genetic (e.g., Arthur Jensen) are characterized as a minority. According to Synderman and Rothman, their survey of expert opinion found that the opposite is true, however proportion of experts supporting these hypotheses today is unknown.

Utility of research

Main article: Race and intelligence (Utility of research)

Theories of race and intelligence have been challenged on grounds of their utility. Critics want to know what purpose such research could serve and why it has been an intense an area of focus for a few researchers. Some defend the research, saying it has egalitarian aims or that it is pure science, others say that the true motivation for the reserch is the same as that of the eugenics movement and other forms of scientific racism.. Even supporters of intelligence research have desccribed such research as analogous to "working with dynamite" or "dangerous play" in sports.

As to whether research in this area is desirable, John C. Loehlin wrote in 1992, "Research on racial differences in intelligence is desirable if the research is appropriately motivated, honestly done, and adequately communicated." [emphasis original] Defenders of the research suggest that both scientific curiosity and a desire to draw benefits from the research are appropriate motivations. Reachers such as Richard Lynn have suggested that conclusions from the research can help make political decisions, such as the type of educational opportunities and expectations of achievement policy makers should have for people of different races. Researchers such as Charles Murray have used their conclusions to criticize social programs based on racial equality that fail in Murray's eyes to recognize the realities of racial differences.

Sociologist and demographer Reanne Frank says that some race and intelligence research has been abused "The most malignant are the "true believers," who subscribe to the typological distinctions that imply hierarchical rankings of worth across different races. Although this group remains small, the members' work is often widely publicized and well known (e.g., Herrnstein and Murray 1994; Rushton 1991)"

utility subarticle conent

Theories of race and intelligence have been challenged on grounds of their utility. Critics want to know what purpose such research could serve and why it has been an intense an area of focus for a few researchers. Some defend the research, saying it has egalitarian aims or that it is pure science, others say that the true motivation for the reserch is the same as that of the eugenics movement and other forms of scientific racism.. Even supporters of intelligence research have desccribed such research as analogous to "working with dynamite" or "dangerous play" in sports.

As to whether research in this area is desirable, John C. Loehlin wrote in 1992, "Research on racial differences in intelligence is desirable if the research is appropriately motivated, honestly done, and adequately communicated." [emphasis original] Defenders of the research suggest that both scientific curiosity and a desire to draw benefits from the research are appropriate motivations. Reachers such as Richard Lynn have suggested that conclusions from the research can help make political decisions, such as the type of educational opportunities and expectations of achievement policy makers should have for people of different races. Researchers such as Charles Murray have used their conclusions to criticize social programs based on racial equality that fail in Murray's eyes to recognize the realities of racial differences.

Sociologist and demographer Reanne Frank says that some race and intelligence research has been abused "The most malignant are the "true believers," who subscribe to the typological distinctions that imply hierarchical rankings of worth across different races. Although this group remains small, the members' work is often widely publicized and well known (e.g., Herrnstein and Murray 1994; Rushton 1991)"

Improved public policy as motivation for doing research

One criticism of the research supporting the partially-genetic positions and claimed public policy implications in Bell Curve, in the magazine the New Republic was:

Our society, our polity, our elites, according to Herrnstein and Murray, live with an untruth: that there is no good reason for this [racial] inequality, and therefore society is at fault and we must try harder. I ask myself whether the untruth is not better for American society than the truth.

More recently, Yale psychologist Robert Sternberg asked whether race and intelligence researchers Arthur Jensen and J. Philippe Rushton show "good taste" in their choice of research topics. Further, he asked,

"What good is research of the kind done by Rushton and Jensen supposed to achieve? Only vaguely cloaked behind their words is the purported demonstration that certain groups are, on average, genetically inferior to other groups, at least in that aspect of intelligence measured by IQ. The articles and books reporting on this research inevitably have the seemingly obligatory final public-policy section, which is somehow supposed to justify, in part, the usefulness of the research. The “Implications for Public Policy” section (Rushton & Jensen, Section 15) that is included in works of this kind (see also Herrnstein & Murray, 1994; Jensen, 1969) seem to have the intention to provide a public-policy rationale for work attempting to show that one group is inferior to another and that not much, if anything, can be done about it. It is therefore worthwhile to examine whether any of the alleged public-policy implications follow from the data. If not, the argument that the research is useful in formulating public policy is impugned."(Template:AYref)

On the other hand, Template:AYref is one supporter of the partially-genetic position and states:

Lying about race differences in achievement is harmful because it foments mutual recrimination. Because the untruth insists that differences cannot be natural, they must be artificial, manmade, manufactured. Someone must be at fault. Someone must be refusing to do the right thing. It therefore sustains unwarranted, divisive, and ever-escalating mutual accusations of moral culpability, such as Whites are racist and Blacks are lazy.

Similarly, J. Phillipe Rushton and Aurthor Jensen argue “we will never make progress in race relations if we operate on the belief that one segment of society is responsible for the plight of another segment and that belief is false.” They argue that policy-makers and judges aggravate racial tensions when they mistakenly attribute “the underachievement of black people to prejudice and discrimination by white people,” rather than to genetic disadvantages. Rushton adds, “It’s very harmful, this philosophy we currently have, which is that anybody, all of us, we can just reinvent ourselves. We can grow and change and develop into something very different, that somehow we’re not constrained genetically…The more you can realize who you are earlier, and that includes race and IQ, then personally the more you can accept it, the easier it will be.” Parents, Rushton explained, easily accept the idea that some of their children are more gifted intellectually or physically than other ones and society, has to accept the same notion.

Some of the less popular proponents of the research, such as Chris Brand feel it is important to maintain a perspective of what they call race realism. The term "race realism" describes the theory that racial distinctions are enduringly important because racial groups differ by nature (genetically) with regard to such important behavioral tendencies as intelligence and impulsiveness. Like other more main-stream researchers they hope that by demonstrating genetic differences in races they can influence and make what they feel will be improvements to public policy.

Racism as motivation for doing research

Image from early scientific text on race Josiah Clark Nott and George Robert Gliddon, Indigenous races of the earth Published 1857.

In the 19th and early 20th century research on race and intelligence was often used to confirm that one race was 'superior' to another. Francisco Gil-White, author of Resurrecting Racism: The Modern Attack on Black People Using Phony Science says that modern reaserch has similar motives. A political motivation is frequently ascribed to those researchers who support the idea that race is a meaningful genetic method of grouping and is significantly linked to intelligence. Many have been described as racists. Researchers such as Amanda Thompson, Elazar Barkan and Steven J. Gould have suggested that "Scientific racism" has been used to perpetuate the idea of the intellectual inferiority of African Americans and that it was used to justify slavery and segregated education in America.

In contrast to this, some academics argue words like racism are used politically in academic contexts to try to artificially close discussions. Robert M. Rosenzweig, former president of the Association of American Universities, states "they are not in my experience typically used to illuminate the debate [but rather] to close the debate [...] by silencing it with a label [such that] the very effort to overcome the label changes the nature of the debate in which one has to engage" (Template:AYref). Glayde Whitney argued in his controversial 1995 presidential address to the Behavior Genetics Association that our emotive responses to uncomfortable racial history have left us with a systemic cognitive bias regarding objective discussion of race matters. Drawing from former Forbes editor Peter Brimelow, Whitney states:

"Since the second world war we have been suffering what [Brimelow] calls 'Adolf Hitler's posthumous revenge on America.' The posthumous revenge is that the intellectual elite of the western world, both political and scientific, emerged from the war 'passionately concerned to cleanse itself from all taints of racism or xenophobia.' The aversion to racism has gone so far that [...] the many and important distinctions between objective investigation of group characteristics, and prejudicial pejorative values are lost in a political atmosphere... [The end effect is that] we feel uneasy because we have been trained - like Pavlov's dog - to recoil from any explicit discussion of race."

Egalitarianism as reason for not doing research

"Moralistic fallacy"

Davis says that research has no relation to what is useful. The position that what is good bears on inquiries into what is has been criticized by Harvard University microbiologist Bernard Davis as the "moralistic fallacy", an implied converse of the naturalistic fallacy, see Template:AYref.

Stephen Pinker argues that opposition to racism is based on moral, not on scientific assumptions: "the case against bigotry is not a factual claim that humans are biologically indistinguishable. It is a moral stance that condemns judging an individual according to the average traits of certain groups..." (The Blank Slate, p. 145).

Linda Gottfredson argues:

The ideal, implicit in many popular critiques of intelligence research, is that all people are born equally able and that social inequality results only from the exercise of unjust privilege. The reality is that Mother Nature is no egalitarian. People are in fact unequal in intellectual potential—and they are born that way, just as they are born with different potentials for height, physical attractiveness, artistic flair, athletic prowess and other traits.

Deliberate straw man

Sternberg (Template:AYref) argues that the moralistic fallacy is a deliberate straw man:

Modern social science has not taken the view that all babies are born with equal intelligence or learning ability. Are there any psychologists who seriously study intelligence who believe that genetic factors play no role in individual differences in intelligence? I doubt it. This is yet another of the many examples of straw men created in their article to foster belief in an untenable position by arguing the alternative. Where there is genuine disagreement in the field is not over whether there are individual differences of genetic origins, but rather whether there are group differences of IQ that are genetic in origin (i.e., of what they believe to be biologically defined racial groups).

Potential for bias subarticle content

Proponents of partly-genetic explanations of race/IQ correlation have often been criticized because much of their work is funded by the Pioneer Fund. The Pioneer Fund has, in turn, been criticized for poor research methods, and even more strongly characterized by the Southern Poverty Law Center as a hate group.

Conversely, supporters of race and intelligence research have accused other scientists of suppressing scientific debate for political purposes. They claim harassment and interference with the work or funding of partly-genetic proponents.

The Pioneer Fund

Main article: Pioneer Fund

Many critics of the genetic hypothesis have criticized the source of much of the funding for researchers supporting this hypothesis, the Pioneer Fund (Template:AYref).

Many of the researchers supporting the genetic explanation of the racial IQ disparity, like the IQ researcher and current head of the fund J. Philippe Rushton, have received grants of varying sizes from the Pioneer Fund. In accord with the tax regulations governing nonprofit corporations, Pioneer does not fund individuals; under the law only other nonprofit organizations are appropriate grantees. As a consequence, many of the fund's awards go not to the researchers themselves but to the universities that employ them, a standard procedure for supporting work by academically based scientists. However, in addition to these awards to the universities where its grantees are based, Pioneer has also made a number of grants to other nonprofit organizations, essentially dummy corporations created solely to channel Pioneer's resources directly to a particular academic recipient. William H. Tucker suggests this is "a mechanism apparently designed to circumvent the institution where the researcher is employed" .

Although the fund typically gives away more than half a million dollars per year, there is no application form or set of guidelines. Instead an applicant merely submits "a letter containing a brief description of the nature of the research and the amount of the grant requested." There is no requirement for peer review of any kind; Pioneer's board of directors—two attorneys, two engineers, and an investment broker—decides, sometimes within a day, whether a particular research proposal merits funding. Once the grant has been made, there is no requirement for an interim or final report or even for an acknowledgment by a grantee that Pioneer has been the source of support, all atypical practices in comparison to other organizations that support scientific research . However, the SPLC itself has been accused of wrongfully applying the term "hate group" to legitimate organizations.

Scientific misconduct and fraud

There has been no serious claim of systematic misrepresentations by race and intelligence researchers as a group. Note that this group includes both advocates and opponents of the genetic hypothesis. However, individual researchers have been accused. When the head of Pioneer Fund and parly-genetic researcher J. Philippe Rushton's claimed supporting references were examined they were found to include a nonscientific semipornographic book and an article in Penthouse Forum.^[34]

The partly-genetic researcher Cyril Burt has been accused of fraud.

Complaints of "political correctness"

Robert A. Gordon, criticized for accepting grants from the Pioneer Fund, responded to media criticisms of grant-recipients by stating: "Politically correct disinformation about science appears to spread like wildfire among literary intellectuals and other nonspecialists, who have few disciplinary constraints on what they say about science and about particular scientists and on what they allow themselves to believe."

Complaints of persecution

It is asserted that misguided political correctness has led to large-scale denial of recent developments in the human sciences. For example, Morton Hunt argues that recent years "have witnessed a dramatic upsurge in efforts to impose limits on the freedom of social scientists to explore controversial research questions, particularly questions that could yield answers distasteful to those with certain sociopolitical or ideological agendas".

Steven Pinker argues a fear of the implications of the science of human nature ("mind, brain, genes, and evolution") has led to the perception that these are dangerous ideas. Pinker states regarding recent discussions regarding group differences:

Whether or not these hypotheses hold up ... proponents of ethnic and racial differences in the past have been targets of censorship, violence, and comparisons to Nazis. Large swaths of the intellectual landscape have been reengineered to try to rule these hypotheses out a priori (race does not exist, intelligence does not exist, the mind is a blank slate inscribed by parents). The underlying fear, that reports of group differences will fuel bigotry, is not, of course, groundless.

Template:AYref summarizes the history of harassment and violence in this area:

For a long time Jensen received death threats, needed body guards while on his campus or others, had his home and office phones routed through the police station, received his mail only after a bomb squad examined it, was physically threatened or assaulted dozens of times by protesters disrupting his talks in the United States and abroad, regularly found messages like "Jensen Must Perish" and "Kill Jensen" scrawled across his office door, and much more. Psychologists Richard Herrnstein and Hans Eysenck also had such experiences during the 1970s for defying right thinking about intelligence—Eysenck, for example, being physically assaulted by protesters during a public lecture at the London School of Economics.

Other examples include: the Rolling Stone magazine featured a 1994 article titled "Professors of HATE" (in five-inch letters) with a photo of J. Phillipe Rushton's face doctored to look "ghoulish." The British Daily Mail headlined a 1999 interview with Arthur Jensen "Is This Man Truly the World's Most Loathsome Scientist?",[35] disruption of lectures, censuring from academic superiors (e.g. Rushton[36]), police investigation (e.g. Rushton in 1989,[37] and Tatu Vanhanen in Finland in 2004[38]), harassment of family (e.g. Hans Eysenck's children were reportedly treated badly by teachers, causing Eysenck to change the family name to Evans[39]), and even death threats (e.g. Jensen, Rushton,[40] and Glayde Whitney), bomb threats (e.g. Jensen, Rushton[41], and Charles Murray) and physical assault (e.g. Eysenck was assaulted by Maoist protestors in 1973 while giving a lecture;[42] Arthur Jensen[43]).

Supporters of race and intelligence research have accused other scientists of suppressing scientific debate for political purposes. Behavioral geneticist Glayde Whitney argued in his controversial 1995 presidential address to the Behavior Genetics Association that suppression of debate on both individual and group hereditary differences has occurred as a result of a larger ideology of "environmental determinism for all important human traits ... [a] 'Marxist-Lysenkoist' denial of genetics."[44]

Scientists who openly support the genetic hypothesis have in a number of occurrences faced harassment and interference with their work or funding. Critic of race science William H. Tucker considers these events to be unjustified, "intolerable violation of academic freedom” (Template:AYref). When J. Phillipe Rushton was being censured by superiors at his University of Western Ontario in 1989 "despite," as Tucker notes, "being the recipient of a prestigious Guggenheim fellowship and having one of the most productive records of peer-reviewed publication in his department," even notable scientists who had criticized his work, such as James Flynn and Jack Block, wrote to the university on his behalf (Template:AYref).

On the other hand, Tucker writes:

Although such incidents are intolerable violations of academic freedom, there is an inescapable irony in the complaints of Pioneer grantees, so many of whom have demonstrated precious little concern that their conclusions have been offered, as part of a concerted campaign by the members of the fund that supports their research, to prevent some of their fellow citizens from attending school with whites, being allowed to use "white" public facilities, or being served in "white" establishments. Challenged to repudiate such misuse of his own work, Jensen has steadfastly refused to do so, claiming to be entirely apolitical, although he did not hesitate to appear before a legislative committee as part of a group of notorious opponents of civil rights seeking to halt school integration. Indeed, Jensen was fully aware that the source of his funds considered him part of the "team" providing the "essential ammunition" for maintaining educational apartheid. Pearson, who quickly cleared his department at the University of Southern Mississippi of faculty with liberal opinions so that he could replace them with unqualified neo-Nazis, authored an outraged book in 1991, lamenting the plight of Pioneer scientists harassed by the forces of political correctness, none of whom have lost their academic positions. Only months later, one of his pseudonymous articles in the Mankind Quarterly called for "modification of the 'Bill of Rights'" to deal with the problem of "uncontrolled immigration" and "ghetto welfare children."

Rushton has not only contributed to American Renaissance publications and graced their conferences with his presence but also offered praise and support for the "scholarly" work on racial differences of Henry Garrett, who spent the last two decades of his life opposing the extension of the Constitution to blacks on the basis that the "normal" black resembled a European after frontal lobotomy. Informed of Garrett's claim that blacks were not entitled to equality because their "ancestors were ... savages in an African jungle," Rushton dismissed the observation as quoted "selectively from Garrett's writing," finding nothing opprobrious in such sentiments because the leader of the scientific opposition to civil rights had made other statements about black inferiority that were, according to Rushton, "quite objective in tone and backed by standard social science evidence." Quite apart from the questionable logic in defending a blatant call to deprive citizens of their rights by citing Garrett's less offensive writing—as if it were evidence of Ted Bundy's innocence that there were some women he had met and not killed—there was no sense on Rushton's part that all of Garrett's claims, whether or not "objective," were utterly irrelevant to constitutional guarantees, which are not predicated on scientific demonstrations of intellectual equality. Understandably and appropriately outraged at the violation of their own academic freedom, Pioneer grantees have found nothing objectionable in attempts, based on scientific conclusions that they have promulgated, to deprive others of their rights.(Template:AYref)

Accusations of "political correctness"

It is asserted by some that misguided political correctness has led to large-scale denial of recent developments in the human sciences, including research regard group differences in cognitive ability. Steven Pinker argues a fear of the implications of the science of human nature ("mind, brain, genes, and evolution") has led to the perception that these are dangerous ideas. Pinker states regarding recent discussions regarding group differences:

Whether or not these hypotheses hold up ... proponents of ethnic and racial differences in the past have been targets of censorship, violence, and comparisons to Nazis. Large swaths of the intellectual landscape have been reengineered to try to rule these hypotheses out a priori (race does not exist, intelligence does not exist, the mind is a blank slate inscribed by parents). The underlying fear, that reports of group differences will fuel bigotry, is not, of course, groundless.

Gottfredson accuses others of maintaining a "double standard" for research that finds unpopular results and a "stiff professional tax on scholars whose work on race or intelligence discomfits reviewers for non-scientific reasons they need not articulate" Gottfredson further argues that high quality of work is no protection from this bias, citing the example of Arthur Jensen as both one of the most eminent and one of the most vilified psychologists, hence the word Jensenism.

Accusations of racism

A racist motivation is frequently ascribed to some researchers who work on questions of race and intelligence. Both historical and contemporary researchers have been described as racists, and some critics hold that it is racist to assert that there are cognitive or behavioral differences between ethnic groups. For example, psychologist Jerry Hirsch has claimed that Arthur Jensen has "avowed goals" that were "as heinously barbaric as were Hitler's and the anti-abolitionists" (Template:AYref).

Accusations have also been aimed at the Pioneer Fund, which according to the Southern Poverty Law Center "has funded most American and British race scientists, including a large number cited in The Bell Curve" The Pioneer fund has been criticized as having a eugenic and racist political agenda , and a claimed racist and Nazi-sympathizer history. Pioneer Fund grantees include the current head J. Phillipe Rushton, Arthur Jensen, Linda Gottfredson, Richard Lynn, Hans Eysenck, Thomas Bouchard, David Lykken, Henry Garrett, William Shockley, Philip Vernon, and Audrey Shuey. Critics of the fund include the SPLC, IQ critic William H. Tucker, and historian Barry Mehler and his Institute for the Study of Academic Racism. The Pioneer fund has been characterized by the Southern Poverty Law Center as being a "hate group," using the definition "attack[ing] or malign[ing] an entire class of people, typically for their immutable characteristics". According to Keith Booker, president of the Wilmington (Del) chapter of the NAACP, the Pioneer Fund "supports only research that tends to come out with results that further the division between races... by justifying the superiority of one race and the inferiority of another... this research is being done in the name of white supremacy." Tucker has argued that some of the prominent researchers advancing genetic explanations have also opposed affirmative action and school integration.(Template:AYref) Prominent critic Ulric Neisser, who was the chairman of the APA's 1995 task force on intelligence research regards the fund as helping "change the face of social science" and as being "a weak plus".

Researchers who accept grants from the Pioneer Fund have been subject to criticism regarding bias. Anti-racist Searchlight Magazine notes Pioneer head J. Phillipe Rushton has given a speech at an American Renaissance meeting that Searchlight describes as a "veritable 'who’s who' of American white supremacy." [45]. In the early 1990s, the University of Delaware imposed a "prohibition on the receipt of funding (by a faculty member) from the Pioneer Fund, amidst accusations that the Fund had a "history of supporting racism, anti-semitism and other discriminatory practices".[46] Grantee Linda Gottfredson fought a two-year battle with the university before it rescinded its prohibition, arguing that a ban on funding restricted academic freedom.[47] Although there is no direct evidence that the Pioneer Fund has biased the research one critic notes:

The real question is not did the Pioneer Fund make you alter your scientific findings but why did the Pioneer Fund fund you? ... It's not so much a question of whether or not they influence an individual scientist but rather the scientists they choose to fund in the first place.

Robert A. Gordon, criticized for accepting grants from the Pioneer Fund, replied to media criticisms of grant-recipients: "Politically correct disinformation about science appears to spread like wildfire among literary intellectuals and other nonspecialists, who have few disciplinary constraints on what they say about science and about particular scientists and on what they allow themselves to believe."

Threats and harassment

Researchers studying race and intelligence have also been subject to threats and harassment. Template:AYref has summarized the history of harassment and violence against Arthur Jensen and others.

For a long time Jensen received death threats, needed body guards while on his campus or others, had his home and office phones routed through the police station, received his mail only after a bomb squad examined it, was physically threatened or assaulted dozens of times by protesters disrupting his talks in the United States and abroad, regularly found messages like "Jensen Must Perish" and "Kill Jensen" scrawled across his office door, and much more. Psychologists Richard Herrnstein and Hans Eysenck also had such experiences during the 1970s for defying right thinking about intelligence—Eysenck, for example, being physically assaulted by protesters during a public lecture at the London School of Economics.

Policy implications

See also: Intelligence and public policy

Public policy implications of IQ and race research are one of the greatest sources of controversy surrounding this issue.

Some proponents of a genetic interpretation of the IQ gap, such as Template:A(Y)ref and Template:A(Y)ref, have sometimes argued that their interpretation does not in itself demand any particular policy response: while a conservative/libertarian commentator may feel the results justify, for example, reductions in affirmative action, a liberal commentator may argue from a Rawlsian point of view (that genetic advantages are undeserved and unjust) for substantial affirmative action. Since all races have representatives at all levels of the IQ curve, this means any policy based on low IQ affects members of all races.

According to the "Mainstream Science on Intelligence" statement published in Intelligence in 1997:

The research findings neither dictate nor preclude any particular social policy, because they can never determine our goals. They can, however, help us estimate the likely success and side-effects of pursuing those goals via different means.

While not specifically race-related, policies focused on geographical regions or nations may have disproportionate influences on certain racial groups and on cognitive development. Differences in health care, nutrition, regulation of environmental toxins, and geographic distribution of diseases and control strategies between the developing world and developed nations have all been subjects of policies or policy recommendations (see health and nutrition policies relating to intelligence).

Finally, germinal choice technology may one day be able to select or change directly alleles found to influence intelligence or racially identifying traits (such as skin color; see gene SLC24A5), making them susceptible to biotechnological intervention.

Appendix - IQ Data from various sources

NOTE: The information in the following tables is referenced to credible sources; however, it should be noted that some of these studies liberally synthesized their results from different sources and test methods. In general comparisons should only be made between similar primary sources, but this is not always possible given the wide variety of IQ tests, the fluid and debatable nature of racial categorization, and the lack of large scale representative data sets. Among the factors that invalidate comparisons across the studies are environment of the test subjects as well as inherent biases in the test procedures.

Richard Lynn, "Race Differences in Intelligence: An Evolutionary Analysis" 2006 Table 16.2 (indigenous populations)	Average IQ
Arctic Peoples	91
East Asians	105
Europeans	99
Native Americans (north & south)	86
Southern Asian & Northern Africans	84
Bushmen (southern Africa)	54
Africans (subsaharan)	67
Australians (aboriginals)	62
Southeast Asians	87
Pacific Islanders	85

Vinko Buj, Personnal. & Individual Differences, Vol. 2, 1981 , pp. 168 to 169 (variances modern Europe)	Average IQ
Dutch (Amsterdam)	109.4
Germans (Hamburg)	109.3
Swedes (Stockholm)	105.8
Italians (Rome)	103.8
Austrians (Vienna)	103.5
Norwegians (Oslo)	101.8
Danes (Copenhagen)	100.7
Bulgarians (Sophia)	96.3
Poland (Warsaw)	108.3
Yugoslavia (Zagreb)	105.7
Switzerland (Zurich)	102.8
Portugal (Lisbon)	102.6
Great Britain (London)	102
Hungary (Budapest)	100.5
Czechoslovakia (Bratislava)	100.4
Spain (Madrid)	100.3
Belgium (Brussels)	99.7
Greece (Athens)	99.4
Ireland (Dublin)	99.2
Finland (Helsinki)	98.1
France (Paris)	96.1

Linda S. Gottfredson, School of Education, University of Delaware“Social Consequences of Group Differences in Cognitive Ability”, 2004 page 24	Average IQ
US Whites	100
US Blacks	85
US Native Americans	90
US Imigrants from nearby hispanic regions	90

Richard Lynn, Business Today, January 2005	Average IQ
Indians in UK (Northern Indo Aryans and Southern Dravidians)	96

James R. Flynn	Average IQ
Asians in America(Korean-, Japanese- and Chinese ancestry)	104
Whites in Minnesota (mainly german and norwegian ancestry)	105
Whites in USA	100.5

Richard Herrnstein & Charles Murray, "The Bell Curve", Free Press, September 1994	Average IQ
Ashkenazi Jews in USA and UK	107-115
Chinese in USA	97-98
Japanese in USA	97-98

End material

See also

• Ashkenazi intelligence
• Brain to body mass ratio
• Craniometry
• Hominid intelligence
• Neuroscience and intelligence
• Height and intelligence
• Race and crime
• Sex and intelligence
• Scientific racism
• The Mismeasure of Man

References

Main article: Race and intelligence (References)

External links

Collective Statements

• The Wall Street Journal: Mainstream Science on IntelligencePDF
• APA Task Force Examines the Knowns and Unknowns of Intelligence
• Statement on "Race" and Intelligence. American Anthropological Association. Adopted December 1994.

Review Papers

• James Flynn and Charles Murray debate - news summary
• June 2005 issue of Psychology, Public Policy, and Law, Vol. 11, No. 2.
  • Thirty Years of Research on Race Differences in Cognitive Ability J. Philippe Rushton & Arthur R. Jensen
  • There Are No Public-Policy Implications Robert J. Sternberg
  • What if the Hereditarian Hypothesis is True? Linda S. Gottfredson
  • Heredity, Environment, and Race Differences in IQ Richard E. Nisbett
  • The Cultural Malleability of Intelligence and Its Impact on the Racial/Ethnic Hierarchy Lisa Suzuki & Joshua Aronson
  • Wanted: More Race Realism, Less Moralistic Fallacy J. Philippe Rushton & Arthur R. Jensen
• Race, Genetics and IQ Richard E. Nisbett (PDF)
• The Inequality Taboo Charles Murray archived version
• The Black-White Test Score Gap (1998) online (page-image) version of ISBN 0-8157-4609-1

Others

• Crippled by Their Culture - Race doesn't hold back America's black rednecks. Nor does racism by Thomas Sowell
• Race and IQ: Part 1, Part 2, Part 3 by Thomas Sowell
• The Skeptic's Dictionary entry on IQ and race
• (Skeptic Magazine): Two book reviews, by Paul R. Gross and Alondra Oubre, of Sarich’s and Miele’s book, Race: The Reality of Human Differences
• Criticism on source material of Bell Curve book
• Poverty and Brain Development in Early Childhood 1999 report
• Miscellaneous articles by Richard Lynn et al.
• Are IQ Tests Biased?
• Scholars Provide an Overview of Explanations for Black-White Test Score Gap
• School Readiness: Closing Racial and Ethnic Gaps
• La Griffe du Lion - pseudonymously released statistical analyses on this and related subjects. (Review)
• A review of the field (Jan. 2006) Kohn, Marek, "This racist undercurrent in the tide of genetic research: As taboos fall away, there's a danger that denial of racial difference will be replaced with uncritical acceptance," The Guardian.
• The Lessons of the Ashkenazim: Groups and Genes, Steven Pinker, June 2006, The New Republic.
• Are all races equally intelligent? -- Or: When is knowledge knowledge? by John J. Ray
• Black-White Gap in IQ Scores Closing, Study Finds