Sex differences in human physiology: Difference between revisions
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A '''sex difference''' is a distinction of biological and/or physiological characteristics typically associated with either males or females of a species in general. In the study of humans, socio-political issues arise in classifying whether a sex difference results from the [[biology of gender]]. This article focuses on quantitative differences which are based on a gradient and involve different averages. For example, men are taller than women on average, but an individual woman may be taller than an individual man. |
A '''sex difference''' is a distinction of biological and/or physiological characteristics typically associated with either males or females of a species in general. In the study of humans, socio-political issues arise in classifying whether a sex difference results from the [[biology of gender]]. This article focuses on quantitative differences which are based on a gradient and involve different averages. For example, men are taller than women on average, but an individual woman may be taller than an individual man. |
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==Economics== |
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Revision as of 15:15, 11 June 2007
A sex difference is a distinction of biological and/or physiological characteristics typically associated with either males or females of a species in general. In the study of humans, socio-political issues arise in classifying whether a sex difference results from the biology of gender. This article focuses on quantitative differences which are based on a gradient and involve different averages. For example, men are taller than women on average, but an individual woman may be taller than an individual man.
Other articles describe differences which clearly represent a binary male/female spilt, such as human reproduction. Women give birth to babies; men never do.
Though some sex differences are controversial, they are not to be confused with sexist stereotypes.
Possible causes: some theories
The existence of a gender difference does not necessarily identify whether the trait is due to nature or environment. Some traits are obviously innate (for example, reproductive organs), others obviously environmental (for example, given names), while for others the relationship is either multi-cause or unknown.
From the viewpoint of evolutionary psychology as championed by David Buss, modern humans have inherited natural traits that were adaptive in a prehistoric environment, including traits that had different advantages for males versus females (see Sexual selection). Gender role theory and Alice Eagly claims that boys and girls learn the appropriate behaviour and attitudes from the family and overall culture they grow up with, and so non-physical gender differences are a product of socialization. These are not all mutually exclusive theories: it is possible that gender differences are partially innate but are then reinforced and exaggerated by the environment.
Some feminists see gender differences as caused by patriarchy or discrimination, although difference feminism argues for an acceptance of natural differences between men and women. Traditional masculists tend to see gender differences as inherent in human nature, while liberal masculists may challenge traditional roles.
Traditional Abrahamic religions sees gender differences as created by God: "He made them in his image: man and woman He made them." (Genesis 1:27) (see Role of women in Judaism, Christian views of women, Gender roles in Islam).
Physical differences
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/28/Expecting_family.jpg/200px-Expecting_family.jpg)
For information about how males and females develop throughout the lifespan, see sexual differentiation.
Appearances
- On average, men are taller than women (See sexual dimorphism).
- Men usually have more body hair than women.
- Men’s skin is thicker (more collagen) and oilier (more sebum) than women’s skin[1].
- Women generally have a smaller waist in comparison to their hips (see waist-hip ratio).
- In men, the second digit (index finger) tends to be shorter than the fourth digit (ring finger), while in females the second tends to be longer than the fourth (see digit ratio).
- On average women tend to have skin that is 3-4% lighter than men[citation needed]. Scientists believe this is an adaptation required for increased production of Vitamin D during pregnancy. Vitamin D is necessary to help the body absorb calcium and deposit it in the bones of fast growing embryos. By having lighter skin more of the sun's UV radiation can penetrate the skin to and increase their ability to produce vitamin D.[1]
Health
- Women generally have a higher body fat percentage than men. [2]
- Women usually have lower blood pressure than men, and women's hearts beat faster, even when they are asleep. [3]
- Men have more muscle tissue mass, particularly in the upper body.
- Men and women have different levels of certain hormones. Men have a higher concentration of androgens while women have a higher concentration of estrogens.
- On average, girls begin puberty approximately two years before boys.
- Adult men have approximately 5.2 million red blood cells per cubic millimetre of blood, whereas women have approximately 4.6 million [4].
- Women tend to have a lower centre of gravity (shorter legs, longer torso, relative to height) and a larger hip section than men
Reproduction
- Female fertility declines after age 35 and ends with the menopause. Men are capable of fathering children into old age, although very recent research point to a positive correlation between a father's age and the inclination to have children with autism.[2]. Adriana Iliescu was reported as the world's oldest woman to give birth, at age 66. Her record stood until Maria del Carmen Bousada de Lara gave birth to twin sons at Sant Pau Hospital in Barcelona, Spain on December 29, 2006, at the age of 67. In both cases IVF was used. The oldest known father was former Australian miner Les Colley, who fathered a child with his wife at age 93[3]
- Men typically produce billions of sperm each month[4], many of which are capable of fertilization. Women typically produce one egg a month that can be fertilized into an embryo. Thus during a lifetime men are able to father a significantly greater number of children than women can give birth to. The most fertile woman, according to the Guinness Book of World Records , was the wife of Feodor Vassilyev of Russia (1707-1782) who had 67 surviving children. The most prolific father of all time is believed to be the last Sharifian Emperor of Morocco, Mulai Ismail (1646-1727) who reportedly fathered more than 800 children from a Harem of 500 women. However for every male that sires two offspring, another male fails to sire an offspring.[5]. It is for this reason that the replacement rate, or the average number of children per person over a lifetime in order to replace an area's population, is calculated based on women and not men.
Neurological
- On average, male brains have approximately 4% more cells and 100 grams more brain tissue than females do. However, both sexes have similar brain weight to body weight ratios. Men have larger left inferior parietal lobes[5], while women have proportionally larger Wernicke's and Broca's areas [6]. Evidence of gender differences in the size of the corpus callosum is ambiguous.
- Women generally have faster blood flow to their brains and lose less brain tissue as they age than men do. [7]
Health
Women live longer than men in most countries (notable exceptions are Afghanistan and Pakistan)[8]. One possible explanation is that more men die young because of war, criminal activity, accidents, and heart disease. The gap between males and females is decreasing in many developed countries as more women take up unhealthy practices that were once considered masculine like smoking and drinking[9], and more men practice healthier living. In Russia, however, the sex-associated gap has been increasing as male life expectancy declines [10].
The World Health Organization (WHO) has produced a number of reports on gender and health [11]. The following trends are shown:
- Overall rates of mental illness are similar for men and women. There is no significant gender difference in rates of schizophrenia and bipolar depression. Women are more likely to suffer from unipolar depression, anxiety, eating disorders, and post-traumatic stress disorder. Men are more likely to suffer from alcoholism and antisocial personality disorder.
- Worldwide, more men than women are infected with HIV. The exception is sub-Saharan Africa, where more women than men are infected.
- Adult males are more likely to be diagnosed with tuberculosis.
- Before menopause, women are less likely to suffer from cardiovascular disease. However, after age 60, the risk for both men and women is the same.
- Overall, men are more likely to suffer from cancer, with much of this driven by lung cancer. In most countries, more men than women smoke, although this gap is narrowing especially among young women.
- Women are twice as likely to be blind than men. In developed countries, this may be linked to higher life expectancy and age-related conditions. In developing countries, women are less likely to get timely treatments for conditions that lead to blindness such as cataracts and trachoma.
- Women are more likely to suffer from osteoarthritis and osteoporosis.
- Worldwide, 2.7 times as many men as women die in traffic accidents.
Anterior cruciate ligament injuries, especially in basketball, occur more often in women than in men.
Certain conditions are X-linked recessive, in that the gene is carried on the X chromosome. Genetic females (XX) will have the disease only if both their X chromosomes are defective with a similar deficiency, whereas genetic males (XY) will have the disease if their only X chromosome is defective. For this reason, such conditions are far more common in males than in females. Examples of X-linked recessive conditions are color blindness, hemophilia, and Duchenne muscular dystrophy.
Psychology
![](http://upload.wikimedia.org/wikipedia/commons/thumb/1/1d/Leaping_boy.jpg/150px-Leaping_boy.jpg)
In one large scale study, most cognitive abilities and psychological traits showed little or no average difference between the sexes [12]. Where sex differences exist, there is often considerable overlap between the sexes[13]; in addition, it is unclear how many of these differences hold true across different cultures. Nevertheless, certain trends tend to be found.
Risk taking
In many situations, men are more prone to taking risks [14].
Personality tests
- In the big five personality traits, women score higher in Agreeableness (tendency to be compassionate and cooperative) and Neuroticism (tendency to feel anxiety, anger, and depression).
- Demographics of MBTI surveys indicate that 60-75% of women prefer feeling and 55-80% of men prefer thinking[15][16].
Aggression
Males are generally more aggressive than females (Coi & Dodge 1997, Maccoby & Jacklin 1974, Buss 2005). There is evidence that males are quicker to aggression (Frey et al 2003) and more likely than females to express their aggression physically (Bjorkqvist et al. 1994). However, some researchers (such as Rachel Simmons) have suggested that females are not necessarily less aggressive, but that they tend to show their aggression in less overt, less physical ways (Bjorkqvist et al. 1994, Hines and Saudino 2003). For example, females may display more verbal and relational aggression, such as social rejection.
Systemizing and empathizing
Females score higher on self-report scales of empathy, on samples ranging from school-age children to adults. Empathy scales include measures of perspective taking, orientation towards another person, empathic concern, and personal distress. However, such measures are subjective and empathy may be more related to gender role rather than sex. [17]
Simon Baron-Cohen's EQ SQ Theory claims that, in general, men are better at systemizing (the desire to analyze and explore systems and rules) and that women are better at empathizing (the ability to identify with other people’s feelings). More males than females are diagnosed with autism and Asperger syndrome. According to Cohen, since autistic and Asperger individuals are very high in systemizing, albeit often in a manner which is hyperfocused, and may even oversimplify more complex systems due to missing certain details, and very low in empathizing as well, they are examples of an "extreme male brain" [18].
Intelligence
Most studies show no significant difference in the average IQ for men and women. However, on average men perform better on tests of spatial and mathematical ability, while women perform better on tests of verbal ability and memory. Also, men's IQ has greater variance, that is, there are more men than women in the very high and very low IQ groups, with women's scores more concentrated around the average.
Communication
Deborah Tannen’s studies found these gender differences in communication styles [19]:
- Men tend to talk more than women in public situations, but women tend to talk more than men at home.
- Females are more inclined to face each other and make eye contact when talking, while males are more likely to look away from each other.
- Girls and women tend to talk at length about one topic, but boys and men tend to jump from topic to topic.
- When listening, women make more noises such as “mm-hmm” and “uh-huh”, while men are more likely to listen silently.
- Women are inclined to express agreement and support, while men are more inclined to debate.
However, not all research supports these claims. One study by Erina MacGeorge found only a 2% difference in the conversational styles of men and women, and reported that in general both sexes communicated in similar ways [20]. Critics, including Suzette Haden Elgin, have suggested that Tannen's findings may apply more to women of certain specific cultural and economic groups than to women in general. There is no evidence to support the belief that women speak far more words than men. [21][22][23]
Happiness
A commentary released by Pew Research Center addressed some questions about the way men and women view their lives [24] :
- Overall, women claim to be far happier than men with their lives, and reported more often that they had made personal progress in the last five years.
- Women show greater concern about family and home life issues, while men express more concern about political issues. Men are happier with their family life and more optimistic about their personal future and that of their children.
Problems with research
Studies of psychological gender differences are controversial and subject to error. Many small-scale studies report differences that are not repeated in larger studies. Self-report questionnaires are subject to bias, particularly if the subjects are told that the questionnaire is testing for gender roles. It is also possible that commentators may exaggerate or downplay differences for ideological reasons.
Economics
![]() | The examples and perspective in this article may not represent a worldwide view of the subject. |
Income
In many countries, there is a gender income gap which favors males in the labor market. For example, the median salary for U.S. women is 76% of that of U.S. men; however, studies find that U.S. women earn 98% of what men do when controlled for experience, education, and number of years on the job. The income gap in other countries ranges from 53% in Botswana to 92% in Malta. There is a debate to what extent this is the result of gender differences, lifestyle choices, or because of discrimination.
Employment
![](http://upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Krankenschwester_Haeuslich0.jpg/200px-Krankenschwester_Haeuslich0.jpg)
According to a 2004 report by the US department of labor [25]:
- 52.9% of American women are in the labor force versus 73.3% of men.
- 70.7% of women with children under 18 are in the workforce (up from 47% in 1975), compared with 94% of men with children under 18.
- Approximately 26 percent of employed women usually work part time, compared with about 11 percent of employed men.
- 5.6% of employed women and 8% of men are self-employed.
- Women in nonagricultural industries work 35.9 hours per week versus 41.6 hours for men.
- Women account for more than half of all workers in the following industries: financial activities, education services, healthcare, leisure and hospitality, and office and administrative support. Women are far more likely than men to be social workers, paralegals and legal assistants, teachers, nurses, speech pathologists, dental hygienists, maids and housekeeping cleaners, and childcare workers.
- More men than women work in the following industries: mining, construction, transportation and utilities, farming, computer and mathematical occupations, engineering, and architecture. Men are far more likely than women to be chief executives, firefighters, police and patrol officers, electricians, dentists, and surgeons.
The Urban Institute reported in 2000 that male teens in the U.S. are more likely than female teens to work 20 or more hours per week [26].
Occupational death
The majority of occupational deaths occur among men. In one U.S. study, 93% of deaths on the job involved men, with a death rate approximately 11 times higher than women. The industries with the highest death rates are mining, agriculture/forestry/fishing, and construction, all of which tend to employ more men than women [27].
Parental leave
Many countries, including Mexico, India, Germany, Brazil, and Australia require companies to grant 12-week maternity leave for working women at full pay. Paternity leave is not available to the same extent, although in Israel for example, parents can use this parental leave as they see fit, dividing the 12 weeks among themselves if necessary regardless of sex.
Insurance
Insurance companies often charge different rates for men and women:
- Health insurance is less expensive for young and middle aged men.
- Automobile insurance companies charge more for teenage boys than their female counterparts.
- Life insurance is higher for males than for females.
Consumer behaviour
Price discrimination can favor either men or women. For example, some night clubs offer discounts or free entry for women, while some hairdressers offer cheaper haircuts for men.
According to a 2000 report, women purchase or influence the purchase of 80% of all consumer goods and influence 80% of health-care decisions [28].
Even though women make a large amount of consumer goods purchases, the driving force behind a lot of those purchases (concerning the more violent videogames, sports, and movies) is male desire.[original research?][citation needed]
Education
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/2d/School_girls_in_Bhaktapur.jpg/150px-School_girls_in_Bhaktapur.jpg)
Worldwide, men are more likely to be literate, with 100 men considered literate for every 88 women. In some countries the difference is even greater; for example, in Bangladesh only 62 women are literate for every 100 men [29].
In an OECD study of 43 developed countries, 15-year-old girls were ahead of boys in literacy skills and were more confident than boys about getting high-income jobs [30].
As of October 2005, women made up 57% of all college students in the United States[31]. This is repeated in other countries; for example, women make up 58% of admissions in the UK [32] and 60% in Iran [33].
Suicide
In western countries, males are much more likely to die by suicide than females (usually by a factor of 3–4:1); 69 out of 74 non-western countries found an excess male mortality from suicide.
While there are more completed male suicides than female, females are more likely to attempt suicide. One possible explanation is that males tend to use more violent, immediately lethal methods than females. Another theory is that females are more likely to use self-harm as a cry for help or attention while males are more likely to genuinely want to end their lives.[citation needed]
Crime
Men are much more likely to be incarcerated than women, although women are a fast-growing demographic group in prison.[34] Males are more likely than females to commit murder.[35] Men are also far more likely than women to be the victims of violent crime.[36]
Internet issues
Internet use
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/6a/Watching_and_Blogging.jpg/150px-Watching_and_Blogging.jpg)
In an American study, the percentage of men using the Internet was ahead of the percentage of women, although this difference disappeared in the under 30s. Men log on more often, spend more time online, and are more likely to be broadband users. Women are more likely to e-mail friends and family about a variety of topics. Men are more likely to use the Internet to pay bills, participate in auctions, and for recreation such as downloading music and videos. Men and women are equally likely to use the Internet for shopping and banking.[37]
Gender-related preferences in web site design
A study was performed at the University of Maryland in 2007[citation needed][specify] which was designed to determine gender differences in preference for various aspects of web site design. Previous studies, in particular one performed at the University of Glamorgan Key website research highlights gender bias, indicated measurable differences between men and women, with each gender tending to prefer sites designed by their own gender. Women showed a preference for pages with more color in the background and typeface, and more rounded shapes. Women also favored informal rather than posed pictures. Men responded better to dark colors and a more linear design. They also were more pleased by a three-dimensional look and images of “self-propelling” rather than stationary objects. The Maryland study sought to confirm these differences.
The subjects were given pairs of web sites to visit and were asked to fill out a short questionnaire immediately afterward. The questionnaires asked simple questions about their reaction to the colors, graphics, site organization as well as an open-ended question in which they were asked to describe their subjective impressions of the sites. Web sites were selected to present significant design dissimilarities so as to assess differences in site design preference. One pair was specifically selected because the sites themselves targeted at male and female users respectively.
The results generally supported earlier research. Women showed a distinct preference for more color and graphics. In addition, while the object scores for the male and female-targeted sites were not significantly different, women showed a significantly higher preference for the female-targeted site. However, it is clear from the responses to the open-ended questions that site content was a significant factor in determine preference for one site over another. It is therefore suggested that in any future study real web sites not be used, but instead neutral-content sites should be designed with variations in style, to eliminate the bias introduced by the site content.
Marriage and sexuality
![](http://upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Western_wedding_dress_in_Taiwan.jpg/150px-Western_wedding_dress_in_Taiwan.jpg)
Dating and marriage customs are dependent on culture and differ greatly across countries and even in subcultures within the same country. For example, many marriages in India are arranged, whereas in the Western World most people choose their own partners. In most societies, men are generally expected to play the more active role in the early stages of courtship, for example in asking the woman for a date.
Age at first marriage
Men are older, on average, when they marry.
Homosexuality
The demographics of sexual orientation in any population is difficult to establish with reasonable accuracy. However, most surveys find that a greater proportion of men than women report that they are exclusively homosexual, whereas more women than men report being bisexual. In most societies, homosexual and bisexual women are more widely accepted than their male counterparts.
Numbers of unmarried people
In the USA, single men are greatly outnumbered by single women at a ratio of 100 single women to every 86 single men [38]. This very much depends on age group, with 118 single men per 100 single women in their 20s, versus 33 single men to 100 single women over 65 [39].
The numbers are different in other countries. For example, China has many more young men than young women, and this disparity is expected to increase[40]. In regions with recent conflict such as Chechnya, women may greatly outnumber men[41].
Online dating
There are still more men than women in online dating websites. According to a November 2003 study by Jupiter Research, men are four times more likely than women to subscribe to an online dating site and twice as likely to browse, post, or respond to a profile [42].
Choosing a partner
In a cross-cultural study by David Buss, men and women were asked to rank certain traits in order of importance in a long-term partner. Both men and women ranked "kindness" and "intelligence" as the two most important factors. Men valued beauty and youth more highly than women, while women valued financial and social status more highly than men[43].
Orgasm
- Men's orgasm is essential for reproduction whereas female orgasm is not. The female orgasm was believed to have no obvious function other than to be pleasurable although recent evidence suggests that it may have evolved as a discriminatory advantage in regards to mate selection. Psychology Today, The Orgasm Wars
- Typical male orgasmic contractions lasts no more than a couple of seconds, while in women, such contractions lasting up to a minute are known.
- According to Kinsey, for about 75% of all males, orgasm is possible to be attained within the first two minutes after initiation of sexual intercourse. For women the average time to reach orgasm is between 10 and 20 minutes. The swiftness of the male system virtually guarantees climactic orgasms for males but is usually too quick to give the female a penetration-induced orgasm. However, the average time to female orgasm via masturbation is significantly less at four minutes [44] [45].
- Male circumcision (removal of the foreskin) does not prevent the ability to orgasm, but female genital cutting usually does. However, the two procedures are not directly comparable; in particular, the phrase "female genital cutting" is used to refer to a wide variety of different practices, from minor ritual cuts to the labia (which are much less likely to impede orgasm) to complete excision of the clitoris.
Clothing
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/6b/Mumbai_woman_in_red_and_blue.jpg/100px-Mumbai_woman_in_red_and_blue.jpg)
In most cultures, different sorts of clothing are considered appropriate for men and women.
- In Western societies, skirts and dresses and high-heeled shoes are usually seen as women's clothing, while neckties are generally worn by men. Trousers were once seen as exclusively male clothing, but are nowadays worn by both sexes. Male clothes are often more practical (that is, they can function well under a wide variety of situations), but a wider range of clothing styles is available for females. Males are typically allowed to bare their chests in a greater variety of public places. It is generally acceptable, to some degree, for a woman to wear traditionally male clothing, but not the other way around.
- Traditional Islam requires both sexes to wear hijab, or modest clothing. What qualifies as "modest" varies in different Muslim societies; however, women are usually required to cover more of their bodies than men are. Articles of clothing worn by Muslim women for purposes of modesty range from the headscarf to the burka.
- Scottish men may choose to wear kilts on ceremonial occasions. Kilts were previously worn as normal clothing by men. Non-Scottish men are increasingly wearing kilts today.
Miscellaneous
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/22/Kid_playing_soccer.jpg/200px-Kid_playing_soccer.jpg)
- The sex ratio of males to females at birth is 105 boys to 100 girls. In some countries, such as China and India, this ratio is skewed, probably due to sex-selective abortion and infanticide.
- Men have more responsibilities and presence in many religions or religious organizations. For example, the Roman Catholic church forbids women to become priests. Men have more rights under Sharia (Islamic law).
- Some societies place restrictions on women during their menstrual cycle.
- Men play in more sports.
- Women take longer to use the bathroom (see potty parity).
- Typically, women spend more time than men doing childcare and household chores (see homemaker).
- In general, women are more involved than men with children.
See also
Notes
- ^ Gender-related features of skin Procter & Gamble Haircare Research Centre 1997
- ^ Bren, Linda (2005) Does Sex Make a Difference? FDA Consumer magazine, July-August 2005 Issue
- ^ Marano, Hara Estroff (2003) The New Sex Scorecard Psychology Today Magazine, Publication Date: Jul/Aug 2003, Last Reviewed: 9 Sep 2005
- ^ Harasty J, Double KL, Halliday GM, Kril JJ, McRitchie DA. (1997) Language-associated cortical regions are proportionally larger in the female brain Archives of Neurology 1997 Feb;54(2):171-6.
- ^ Frederikse ME, Lu A, Aylward E, Barta P, Pearlson G. (1999) Sex differences in the inferior parietal lobe Cerebral Cortex. 1999 Dec;9(8):896-901
- ^ WHO Countries A list that provides links to statistics on various countries, including life expectancy.
- ^ Lifestyle 'hits life length gap' BBC September 16, 2005
- ^ A Country of Widows Viktor Perevedentsev, New Times, May 2006
- ^ Gender, women, and health Reports from WHO 2002-2005
- ^ Hyde, J. S. (2005) Template:PDFlink American Psychologist, Vol. 60, No. 6, pp. 581-592. See also: Men and Women: No Big Difference on the APA-sponsored website, www.psychologymatters.org.
- ^ Young, Cathy (1999) Sex and Sensibility Reason, March 1999
- ^ Larkin, Judith E. (2003) Gender and risk in public performance Sex Roles: A Journal of Research
- ^ Estimated Frequencies of the Types in the United States Population
- ^ Template:PDFlink
- ^ Rachel Karniol, Rivi Gabay, Yael Ochion, Yael Harari (1998) Is gender or gender-role orientation a better predictor of empathy in adolescence? Sex Roles: A Journal of Research, July, 1998
- ^ Baron-Cohen, Simon (2003) 'They just can't help it' The Guardian April 17, 2003
- ^ Tannen, Deborah (1990) Sex, Lies and Conversation; Why Is It So Hard for Men and Women to Talk to Each Other? The Washington Post, June 24, 1990
- ^ MacGeorge, Erina (2004) Purdue study shows men, women share same planet Purdue News, February 17, 2004
- ^ Liberman, Mark (2006) Sex-Linked Lexical Budgets Language Log, August 06, 2006
- ^ Hyde, Janet Shibley and Linn, Marcia C. (1988) "Gender Differences in Verbal Ability: A Meta-Analysis", Psychological Bulletin, 104:1 53-69
- ^ James, Deborah and Drakich, Janice (1993) "Understanding Gender Differences in Amount of Talk: A Critical Review of Research", in D. Tannen, (ed.) Gender and Conversational Interaction. Oxford University Press: New York and Oxford.
- ^ Global Gender Gaps: Women Like Their Lives Better Pew Research Center October 29, 2003
- ^ Template:PDFlink US Dept of Labor 2005
- ^ Are Teens in Low-Income and Welfare Families Working Too Much? Robert I. Lerman, Urban Institute, November 01, 2000
- ^ Fatal Occupational Injuries - United States, 1980-1997 MMWR Weekly, April 27, 2001
- ^ Popcorn, Faith and Hyperion, Lys Marigold (2000) EVEolution – The Eight Truths of Marketing to Women New York. (ISBN 0-7868-6523-7)
- ^ Illiteracy 'hinders world's poor' BBC November 09, 2005
- ^ 'Girls top of the class worldwide' BBC September 16, 2003
- ^ College gender gap USA Today October 19, 2005
- ^ 'Where have all the young men gone? ' The Guardian May 18, 2004
- ^ 'In Iran, More Women Leaving Nest for University' The New York Times July 22, 2000
- ^ Prevalence of Imprisonment in the U.S. Population, 1974-2001 U.S. Department of Justice Special Report, August 2003, NCJ 197976.
- ^ Most victims and perpetrators in homicides are male U.S. Department of Justice · Office of Justice Programs Bureau of Justice Statistics, 2004
- ^ Sex Differences in Violent Victimization U.S. Department of Justice Special Report September 1997, NCJ-164508.
- ^ How men and women use the Internet Pew Research Center December 28, 2005
- ^ 'Men hold the edge on gender gap odds' Oakland Tribune October 21, 2003
- ^ Facts for features: Valentine’s Day U.S. Census Bureau Report February 7, 2006
- ^ '40m Bachelors And No Women' The Guardian March 09, 2004
- ^ 'Polygamy Proposal for Chechen Men' BBC January 13, 2006
- ^ Scott, Kenneth (2005) 'Why Online Dating is So Tough For Men' solveyourproblem.com February 3, 2005
- ^ Buss, D. M. (2003). The evolution of desire: Strategies of human mating. New York: Basic Books. (ISBN 0-465-02143-3)
- ^ Sexual Averages 1997-2003 Holodyne, Inc.
- ^ The story of Ohh! The Guardian 28 April 2004
- ^ Template:PDFlink
- ^ Advancing Paternal Age and Autism, Reichenberg et al, Archives of General Psychiatry
- ^ oldest birth parents
- ^ National institute of health
- ^ Template:PDFlink
Further reading
- Geary, D. C. (2006). Sex differences in social behavior and cognition: The utility of sexual selection for hypothesis generation. Hormones and Behavior, 49, 273-275. Full text