Skip to main content

Verified by Psychology Today

The Pseudoscience of Race Differences in Penis Size

A paper's claim about racial differences in penis size are unfounded.

A study by Richard Lynn claims to have found scientific evidence that there are substantial differences in the average penis length of men from different races. These claims are in line with vulgar racial stereotypes and are part of a larger research agenda based on a belief in "race realism."

Advocates of race realism argue that there are real and pervasive differences between racial groups in personality, intelligence, and social behaviour, that these differences have a genetic and evolutionary origin, and that they can explain disparities in important social and economic outcomes between races.

Lynn’s theories about race rest on shaky foundations and the data sources he uses as evidence for his claims about penis sizes are untrustworthy. For these reasons, his claims should be disregarded as unscientific.

Lynn’s (2013) proposal is based on the theories of the late J. Philippe Rushton. As noted in a previous article, Rushton, a notorious advocate of race realism, proposed that the major races can be sorted into a human hierarchy based on their supposed reproductive strategies.

According to Rushton’s r-K life history theory, there are two main reproductive strategies that form the ends of a continuum. The r-strategy involves large numbers of offspring with minimal investment, whereas the K-strategy involves fewer offspring and greater investment. According to Rushton, Africans are the most r-selected whereas Asians are the most K-selected, and Europeans are somewhere in between, although closer to Asians than Africans. Rushton claimed that these two reproductive strategies were associated with a whole suite of mental and physical characteristics including brain size, intelligence, criminality, and, of course, penis length. According to this theory, African men have the smallest brains and the largest penises, whereas Asian men are the opposite. This has been described as a Goldilocks theory of race, in which European men are "just right," having a combination of high intelligence and a reasonable genital endowment.

Rushton responded to criticisms of his racist theories by arguing that scientific theories should be judged on the merits of their evidence. Unfortunately for him, it is on scientific grounds that his theories fall apart (Weizmann, Wiener, Wiesenthal, & Ziegler, 1990). Weizmann et al. have argued that Rushton’s assignment of particular traits to either r or K strategies is completely arbitrary. He claims that the K strategy promotes altruism and cooperative behaviour, whereas the r strategy promotes inter-male aggression and criminality.

However, according to biological models, K strategies appear under conditions of intense competition for limited resources and so there is no reason to associate K with altruism or r with criminality. Additionally, the original theory predicts that unstable fluctuating environments would favour r-strategies, whereas stable, predictable environments would favour K strategies. Hot topical environments have higher levels of stability than colder ones. According to this theory, Africans who developed in tropical environment should be highly K-selected, contrary to Rushton’s theory.

Rushton’s theory has also been criticised for naïveté about sexual matters (Weizmann, et al., 1990). He assumed that larger genital size means less sexual restraint, more frequent intercourse, and therefore more frequent procreation. These assumptions are unjustified as humans regularly engage in non-procreative sexual activity. Furthermore, sexual mores within a society can change within a generation from prudishness to permissiveness and back again. Rushton’s theory assumes that sexual interests are genetically based, yet genes cannot substantially change within a generation.

Rushton and Bogaert (1987) argued that blacks are more sexually precocious and less sexually restrained than whites, based on Kinsey’s out-dated and non-representative data. However, they ignore information from the same source that contradicted their theory, such as that blacks were more prudish than whites about nudity, and that blacks were less likely to have a prostitute as a first sexual partner. Kinsey also found that whites engage in more non-coital sexual behaviour, such as oral-genital contact, than Blacks. Rushton interprets this as indicating that Whites are less reproductively oriented (hence more K-selected) even though this contradicts his argument that K-strategies are associated with greater sexual restraint and presumably less sexual activity in general (Weizmann, et al., 1990).

Rushton assumes that because K-strategies are less reproductively oriented, members of the K-selected races should have fewer children. However, fertility is sensitive to environmental and social conditions (Weizmann, et al., 1990). In colonial times, North America experienced historically high rates of fertility, yet in modern times, fertility in North America has declined to the low rates seen in modern European countries. Furthermore, Chinese peoples have historically had high rates of fertility, in spite of being highly K-selected according to Rushton.

Lynn attempts to justify his belief that there are differences between races in penis length on the basis that European and Asian males have lower levels of testosterone than Africans and that the “reduction of testosterone had the effect of reducing penis length, for which evidence is given by Widodsky and Greene (1940).” Widodsky and Greene (1940) is actually a study of the effects of sex hormones on the penises of rats. This is hardly convincing evidence that there are racial differences in testosterone levels or that a reduction in penis length ever occurred in human history.

Lynn's claims about differences in penis length between races build on earlier claims by Rushton and Bogaert (1987). The Rushton and Boagert paper is striking for its use of non-scholarly sources (Weizmann, Wiener, Wiesenthal, & Ziegler, 1991). These include a book of semi-pornographic “tall tales” by an anonymous 19th-century French surgeon that makes wildly inconsistent claims about genital sizes in people of different races. Lynn also refers to this book without mentioning any problems with this as a source of information. Another odd data source cited by Rushton and Bogaert is an article authored by a certain “P. Nobile” published in Forum: International Journal of Human Relations. This publication is better known to the public as “The Penthouse Forum,” a popular men’s magazine.

The data sources that Lynn uses in his recent paper are hardly much better. One of them is a book by Donald Templer (another self-professed race realist[1]) called Is Size Important? Templer is not a urologist but a psychologist so why he would claim to be an authority on this subject is unclear.[2]

Lynn’s other source is the world penis size website. These are both self-published sources that have not been independently verified. A blogger named Ethnic Muse has carefully examined this site’s references and found that a number of articles listed on the site either do not exist under the name given or do not discuss penis size at all. There are also numerous discrepancies between the values provided by the website and the actual values given by the references.[3] Therefore, the information on this website cannot be trusted and no conclusions should be drawn from it.

Lynn’s paper was an attempt to validate one of the claims of Rushton’s r-K theory that there are predictable differences between races in a range of physical and psychological characteristics, including penis length. However, this theory is unscientific and makes arbitrary claims, many of which have been refuted in considerable detail (Weizmann, et al., 1990, 1991). Furthermore, Lynn did not consult authoritative sources for his paper, such as urologists or urology journals. The data sources he did use for his paper are untrustworthy and therefore his results, like his theory, should not be taken seriously.[4] The very relevance of penis length to understanding whatever racial differences may exist would seem to be highly doubtful.


[1] Among other things, Templer apparently advocates the voluntary sterilisation of welfare recipients on eugenics grounds.

[2] I am grateful to an anonymous blog article for pointing this out.

[3] I can confirm this. One of the references cited is titled “Male penis length average in sub-Saharan Africa, circumcision, and relation to AIDS: a review” and supposedly appeared in the journal AIDS and Behavior in 2007. I searched this journal and no article by this name could be found.

[4] A paper by Tatu Westling makes the ludicrous claim that a country’s economic growth is inversely correlated with penis size based on data from this website.

© Scott McGreal. Please do not reproduce without permission. Brief excerpts may be quoted as long as a link to the original article is provided.

Follow him on Facebook, Google Plus, or Twitter.


Lynn, R. (2013). Rushton’s r–K life history theory of race differences in penis length and circumference examined in 113 populations. Personality and Individual Differences, 55(3), 261-266. doi:

Rushton, J. P., & Bogaert, A. F. (1987). Race Differences in Sexual Behavior: Testing an Evolutionary Hypothesis. Journal of Research in Personality, 21, 529-551.

Weizmann, F., Wiener, N. I., Wiesenthal, D. L., & Ziegler, M. (1990). Differential K theory and racial hierarchies. Canadian Psychology, 31(1), 1-13. doi: 10.1037/h0078934

Weizmann, F., Wiener, N. I., Wiesenthal, D. L., & Ziegler, M. (1991). Eggs, eggplants and eggheads: a rejoinder to Rushton. Canadian Psychology, 32(1), 43-50. doi: 10.1037/h0078958

More from Psychology Today

More from Scott A. McGreal MSc.

More from Psychology Today