In societies that regard some races of people as dominant or superior and others as subordinate or inferior, hypodescent is the automatic assignment of children of a mixed union or mating between members of different socioeconomic groups or ethnic groups to the subordinate group. The opposite practice is hyperdescent, in which children are assigned to the race that is considered dominant or superior.
Parallel practices include agnatic descent, matrilineality and cognatic descent, which assign race according to the father, mother, or some combination, without regard to the race of the other parent. Since either parent (or both) might be of mixed-race, hypo- and hyper-descent can operate in tandem with, or separately from, a system of agnatic or cognatic racial assignment.
The American practice of applying a rule of hypodescent began its development in the colonies, as slavery was established. But, it developed in its most strict legal definitions and application after the end of slavery in the early 20th century. After the Reconstruction era, white Democrats regained power in southern states and reasserted white political supremacy through the passage of disfranchising legislation and constitutional amendments, as well as Jim Crow laws, including racial segregation. States followed this with more stringent laws classifying more persons as black based on traceable or any ancestry. For example, in 1822 Virginia, a person was considered legally white with up to one-fourth African ancestry (equivalent to one grandparent). Under its Racial Integrity Act of 1924, Virginia defined as black a person with any known African ancestry, no matter how many generations in the past. It also established a binary classification system for vital records, assigning persons to white or black categories (the latter was essentially all other, into which Native Americans were included.)
Because southern states made slavery an inherited caste, with children taking on the status of the mother, the slave states freed white fathers from economic and social responsibility and kept control of mixed-race unions. They were typically the children of white planters, or their sons or overseers, who had relationships with or had raped and impregnated, enslaved women. By the 18th century in Virginia, travelers already noted the high rate of mixed-race people, and many shades of color found among slaves. There were traveler reports of "white slaves", meaning those who looked white and had only a small part of African ancestry. Among the notable examples of wealthy white planters who took longtime slave companions after becoming widowers, were reportedly John Wayles, Thomas Jefferson's father-in-law, and Thomas Jefferson. Each was said to have several children in the relationships. Both Wayles and Jefferson were said to have had a relationship with a slave woman of mixed race. Their children were majority white by ancestry; Jefferson's alleged children by Sally Hemings were seven-eighths white.
The Southern author Mary Chesnut wrote in her famous A Diary from Dixie of the Civil War-era about the hypocrisy of a woman's recognizing white men's children among the slaves in every household but her own. Fanny Kemble, the British actress who married an American slaveholder, wrote about her observations of slavery as well, including the way white men used slave women and left their mixed-race children enslaved.
Sometimes the white fathers freed the children and/or their mothers, or provided education or apprenticeship, or settled property on them in a significant transfer of social capital. Notable antebellum examples were the fathers of Charles Henry Langston and John Mercer Langston, and the father of the Healy family of Georgia. Other mixed-race children were left enslaved; some were sold away by their fathers.
Research by historians and genealogists has shown that unlike the above examples, most African Americans free in Virginia and nearby states in the colonial period were descended from relationships between white women, indentured servant or free, and African or African-American men, indentured servant, free or slave. This reflected the fluid nature of relationships among the working classes before slave rules were made strict. Because the mothers were white, the children were free born. By the turn of the nineteenth century, many free African Americans, along with European-American neighbors, migrated to frontier areas of Virginia, North Carolina, and then further west. Such families sometimes settled in insular groups and were the origin of some isolated settlements, which have long claimed or were said to be of American Indian or Portuguese ancestry.
In its most extreme form in the United States, hypodescent was the basis of the "one drop rule", meaning that if an individual had any black ancestry, the person was classified as black. New laws were passed in southern states and others long after the end of slavery to define white and black, under associated laws for segregation. Tennessee adopted such a "one-drop" statute in 1910, and Louisiana soon followed. Then Texas and Arkansas in 1911, Mississippi in 1917, North Carolina in 1923, Virginia in 1924, Alabama and Georgia in 1927, and Oklahoma in 1931. During this same period, Florida, Indiana, Kentucky, Maryland, Missouri, Nebraska, North Dakota, and Utah retained their old "blood fraction" statutes de jure, but amended these fractions (one-sixteenth, one-thirtysecond) to be equivalent to one-drop de facto.
By 1924 there would have been many "white" people in Virginia who would have had some African and/or Native American ancestry. At the same time that Virginia was trying to harden racial caste, African Americans were organizing to overturn segregation and regain civil rights lost to Jim Crow laws and disfranchisement of the majority of the black community. Established in 1909, the National Association for the Advancement of Colored People (NAACP) took the lead in filing lawsuits to overturn such provisions.
Anti-miscegenation marriage laws 
By the early 1940s, of the thirty U.S. states that had anti-miscegenation laws, seven states (Alabama, Arizona, Georgia, Montana, Oklahoma, Texas, and Virginia) had adopted the one-drop theory for rules prohibiting interracial marriages. This was part of a continuing social hardening of racial lines after the turn of the century, when southern states imposed legal segregation and disfranchised African Americans.
Other states applied the hypodescent rule without carrying it to the "one-drop" extreme, using instead a blood quantum standard. For example, Utah's anti-miscegenation law prohibited marriage between a white and anyone considered a negro, mulatto, quadroon, octoroon, Mongolian, or member of "the Malay race" (here referring to Filipinos). No restrictions were placed on marriages between people who were not "white persons". The law was repealed in 1963.
Other examples of application 
- In the United States, hypodescent is used to define the race of children of mixed-race couples where one of the parents is classified as "black" or either is considered to have any trace of African descent. That practice seems to be diminishing; on the other hand, since the 1960s particularly and the rise of the Black Power movement, many members of the African-American community have insisted that all mixed-race individuals should be identified as black if they have any African-American ancestry.
In the US, people less consistently apply hypodescent in intermarriage between whites and other ethnic groups, such as Native Americans, Hispanics, and Asians.
Evolutionary biologist Richard Dawkins, in The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution, observes in passing that in the United States and Great Britain, societies have developed something like "genetic dominance" in our use of language to identify children from mixed race unions. He notes first, that people seem to be eager to embrace racial classification, even when talking about people of obviously mixed parentage; and second, that we tend not to describe people as of mixed race. Mixed-race children of European-African unions tend to be identified as "black", in what Dawkins calls a "cultural or memetic dominant." He opines that this may be a cross-cultural practice with a biological basis; that perhaps humans are genetically wired to recognize and differentiate among minor superficial differences, in contrast to what we share in our "unusually high level of genetic uniformity in the human species." It is difficult to say what evolutionary purpose such differentiation served; perhaps it contributed to group solidarity when groups lived further apart in different regions and were divided by many cultural factors. He suggests that such differentiation may be an "information-rich way to classify people."
References in culture 
In the book Hypodescent - Discovering You Are Not Black: A Memoir[dead link] the author, an adoptee, describes how he was classified as African American at birth because of his phenotype. Later in life he would realize he does not have any sub-saharan ancestry at all.
The US late 19th century author Charles Chesnutt, of mixed European and African heritage, wrote numerous stories set in the post-Civil War South about the social issues related to the choices of people of color.
In the musical Show Boat, a white man in love with a mulatto woman is accused by the sheriff of violating the state's anti-miscegenation laws. The white man promptly pricks the woman's finger with a knife, swallows a drop of blood, then tells the sheriff "I'm no white man -- I've got negro blood in me." The sheriff lets him off.
See also 
- Racial segregation
- Racial purity
- Kottak, Conrad Phillip. "Chapter 11: Ethnicity and Race." Mirror for Humanity a Concise Introduction to Cultural Anthropology. New York, NY: McGraw-Hill, 2009. 238. Print.
- Christine B. Hickman, "The Devil and the One-Drop Rule: Racial Categories, African Americans, and the U.S. Census", Michigan Law Review, Vol: 95, March, 1997, 1175-1176.
- Paul Heinegg, Free African Americans of Virginia, North Carolina, South Carolina, Maryland and Delaware, accessed 15 Feb 2008
- Pauli Murray, ed. States’ Laws on Race and Color (Athens, 1997), 428, 173, 443, 37, 237, 330, 463, 22, 39, 358, 77, 150, 164, 207, 254, 263, 459.
- Finkelman, "The Color of Law", Northwestern University Law Review, Spring, 1992, Vol. 87, 955, note 96.
- Richard Dawkins, The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution (Boston, New York: Houghton Mifflin, 2004), 401-03.
- Richard Dawkins, The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution (Boston, New York: Houghton Mifflin, 2004), 405
- Richard Dawkins, The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution (Boston, New York: Houghton Mifflin, 2004), 408
Additional reading 
- Thomas e. Skidmore, Black into White: Race and Nationality in Brazilian Thought (Durham: Duke University press, 1993)
- Ian F. Haney Lopez, White by Law: The Legal Construction of Race (NY: New York University Press: 1996)
- David A. Hollinger, "Amalgamation and Hypodescent: The Question of Ethnoracial Mixture in the History of the United States," American Historical Review, Vol. 108., No. 5 (Dec. 2003): 1363-90.
- Pierre Savy, « Transmission, identité, corruption. Réflexions sur trois cas d’hypodescendance », L’homme. Revue française d’anthropologie, 182, 2007 (« Racisme, antiracisme et sociétés »), p. 53-80.