Home » Evolution » Race Differences in Penis Size Revisited: Is Rushton’s r/K Theory of Race Differences in Penis Length Confirmed?

Race Differences in Penis Size Revisited: Is Rushton’s r/K Theory of Race Differences in Penis Length Confirmed?

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Charles Darwin

Denis Noble

JP Rushton

Richard Lynn

L:inda Gottfredson



2050 words

In 1985 JP Rushton, psychology professor at the University of Ontario, published a paper arguing that r/K selection theory (which he termed Differential K theory) explained and predicted outcomes of what he termed the three main races of humanity—Mongoloids, Negroids and Caucasoids (Rushton, 1985; 1997). Since Rushton’s three races differed on a whole suite of traits, he reasoned races that were more K-selected (Caucasoids and Mongoloids) had slower reproduction times, higher time preference, higher IQ etc in comparison to the more r-selected Negroids who had faster reproduction times, lower time preference, lower IQ etc (see Rushton, 1997 for a review; also see Van Lange, Rinderu, and Bushmen, 2017 for a replication of Rushton’s data not theory). Were Rushton’s assertions on race and penis size verified and do they lend credence to his Differential-K claims regarding human races?

Rushton’s so-called r/K continuum has a whole suite of traits on it. Ranging from brain size to speed of maturation to reaction time and IQ, these data points supposedly lend credence to Rushton’s Differential-K theory of human differences. Penis size is, of course, important for Rushton’s theory due to what he’s said about it in interviews.

Rushton’s main reasoning for penis size differences between race is “You can’t have both”, and that if you have a larger brain then you must have a smaller penis; if you have a smaller penis you must have a larger brain. He believed there was a “tradeoff” between brain size and penis size. In the book Darwin’s Athletes: How Sport Has Damaged Black America and Preserved the Myth of Race, Hoberman (1997: 312) quotes Rushton: “Even if you take something like athletic ability or sexuality—not to reinforce stereotypes or some such thing—but, you know, it’s a trade-off: more brain or more penis. You can’t have both.” This, though, is false. There is no type of evidence to imply that this so-called ‘trade-off’ exists. In my readings of Rushton’s work over the years, that’s always something I’ve wondered: was Rushton implying that large penises take more energy to have and therefore the trade-off exists due to this supposed relationship?

Andrew Joyce of the Occidental Observer published an article the other day in defense of Richard Lynn. Near the end of his article he writes:

Another tactic is to belittle an entire area of research by picking out a particularly counter-intuitive example that the public can be depended on to regard as ridiculous. A good example is J. Philippe Rushton’s claim, based on data he compiled for his classic Race, Evolution and Behavior, that average penis size varied between races in accord with the predictions of r/K theory. This claim was held up to ridicule by the likes of Richard Lewontin and other crusaders against race realism, and it is regularly presented in articles hostile to the race realist perspective. Richard Lynn’s response, as always, was to gather more data—from 113 populations. And unsurprisingly for those who keep up with this area of research, he found that indeed the data confirmedRushton’s original claim.

The claim was ridiculed because it was ridiculous. This paper by Lynn (2013) titled Rushton’s r-K life history theory of race differences in penis length and circumference examined in 113 populations is the paper that supposedly verifies Rushton’s theory regarding race differences in penis size, along with one of its correlates in Rushton’s theory (testosterone). Lynn (2013) proclaims that East Asians are the most K-evolved, then come Europeans, while Africans are the least K-evolved. This, then, is the cause of the supposed racial differences in penis size.

Lynn (2013) begins by briefly discussing Rushton’s ‘findings’ on racial differences in penis size while also giving an overview of Rushton’s debunked r/K selection theory. He then discusses some of Rushton’s studies (which I will describe briefly below) along with stories from antiquity of the supposed larger penis size of African males.

Our old friend testosterone also makes an appearance in this paper. Lynn (2013: 262) writes:

Testosterone is a determinant of aggression (Book, Starzyk, & Quinsey, 2001; Brooks & Reddon, 1996; Dabbs, 2000). Hence, a reduction of aggression and sexual competitiveness between men in the colder climates would have been achieved by a reduction of testosterone, entailing the race differences in testosterone (Negroids > Caucasoids > Mongoloids) that are given in Lynn (1990). The reduction of testosterone had the effect of reducing penis length, for which evidence is given by Widodsky and Greene (1940).

Phew, there’s a lot to unpack here. (I discuss Lynn 1990 in this article.) Testosterone does not determine aggression; see my most recent article on testosterone (aggression increases testosterone; testosterone does not increase aggression. Book, Starzyk and Quinsey, 2001 show a .14 correlation between testosterone and aggression, whereas Archer, Graham-Kevan, and Davies 2005 show the correlation is .08). This is just a correlation. Sapolsky (1997: 113) writes:

Okay, suppose you note a correlation between levels of aggression and levels of testosterone among these normal males. This could be because (a)  testosterone elevates aggression; (b) aggression elevates testosterone secretion; (c) neither causes the other. There’s a huge bias to assume option a while b is the answer. Study after study has shown that when you examine testosterone when males are first placed together in the social group, testosterone levels predict nothing about who is going to be aggressive. The subsequent behavioral differences drive the hormonal changes, not the other way around.

Brooks and Reddon (1996) also only show relationships with testosterone and aggressive acts; they show no causation. This same relationship was noted by Dabbs (2000; another Lynn 2013 citation) in prisoners. More violent prisoners were seen to have higher testosterone, but there is a caveat here too: being aggressive stimulates testosterone production so of course they had higher levels of testosterone; this is not evidence for testosterone causing aggression.

Another problem with that paragraph quoted from Lynn (2013) is that it’s a just-so story. It’s an ad-hoc explanation. You notice something with data you have today and then you imagine a nice-sounding story to attempt to explain your data in an evolutionary context. Nice-sounding stories are cool and all and I’m sure everyone loves a nicely told story, but when it comes to evolutionary theory I’d like theories that can be independently verified of the data they’re trying to explain.

My last problem with that paragraph from Lynn (2013) is his final citation: he cites it as evidence that the reduction of testosterone affects penis length…..but his citation (Widodsky and Green, 1940) is a study on rats… While these studies can give us a wealth of information regarding our physiologic systems (at least showing us which types of avenues to pursue; see my previous article on myostatin), they don’t really mean anything for humans; especially this study on the application of testosterone to the penis of a rat. See, the fatal flaw in these assertions is this: would a, say, 5 percent difference in testosterone lead to a larger penis as if there is a dose-response relationship between testosterone and penis length? It doesn’t make any sense.

Lynn (2013), though, says that Rushton’s theory doesn’t propose that there is a direct causal relationship between “intelligence”‘ and penis length, but just that they co-evolved together, with testosterone reduction occurring when Homo sapiens migrated north out of Africa they needed to cooperate more so selection for lower levels of testosterone subsequently occurred which then shrunk the penises of Rushton’s Caucasian and Mongoloid races.

Lynn (2013) then discusses two “new datasets”, one of which is apparently in Donald Templer’s book Is Size Important (which is on my to-read list, so many books, so little time). Table 1 below is from Lynn reproducing Templer’s ‘work’ in his book.

Lynn table 1

The second “dataset” is extremely dubious. Lynn (2013) attempts to dress it up, writing that “The information in this website has been collated from data obtained by research centres and reports worldwide.Ethnicmuse has a good article on the pitfalls of Lynn’s (2013) article. (Also read Scott McGreal’s rebuttal.)

Rushton attempted to link race and penis size for 30 years. In a paper with Bogaert (Rushton and Bogaert, 1987), they attempt to show that blacks had larger penises than whites who h ad longer penises than Asians which then supposedly verified one dimension of Rushton’s theory. Rushton (1988) also discusses race differences in penis size, citing a previous paper by Rushton and Bogaert, where they use data from Alfred Kinsey, but this data is nonrepresentative and nonrandom (see Zuckermann and Brody, 1988 and Weizmann et al, 1990: 8).

Still others may attempt to use supposed differences in IGF-1 (insulin-like growth factor 1) as evidence that there is, at least, physiological evidence for the claim that black men have larger penises than white men, though I discussed that back in December of 2016 and found it strongly lacking.

Rushton (1997: 182) shows a table of racial differences in penis size which was supposedly collected by the WHO (World Health Organization). Though a closer look shows this is not true. Ethnicmuse writes:

ANALYSIS: The WHO did not study penis sizes. It relied on three separate studies, two of which were not peer-reviewed and the data was included as “Appendix III” (which should have alerted Rushton that this was not an original study). The first study references Africans in the US (not Africa!) and Europeans in the US (not Europe!), the second Europeans in Australia (not Europe!) and the third, Thais.

So it seems to be bullshit all the way down.

Ajmani et al (1985) showed that 385 healthy Nigerians had an average penile length of 3.21 inches (flaccid). Orakwe and Ebuh (2007) show that while Nigerians had longer penises than other ethnies tested, the only statistical difference was between them and Koreans. Though Veale et al (2014: 983) write that “There are no indications of differences in racial variability in our present study, e.g. the study from Nigeria was not a positive outlier.”

Lynn and Dutton have attempted to use androgen differentials between the races as evidence for racial differences in penis size (this is another attempt at a physiological argument to attempt to show the existence of racial differences in penis size). Edward Dutton attempted to revive the debate on racial differences in penis size during a 2015 presentation where he, again, showed that Negroids have higher levels of testosterone than Caucasoids who have higher levels of androgens than Mongoloids. These claims, though, have been rebutted by Scott McGreal who showed that populations differences in androgen levels are meaningless while they subsequently fail to validate Rushton and Lynn’s claims on racial differences in penis size.

Finally, it was reported the other day that condoms from China were too small in Zimbabwe, per Zimbabwe’s health minister. This led Kevin MacDonald to proclaim that this was “More corroboration of race differences in penis size which was part of the data Philippe Rushton used in his theory of r/K selection (along with brain size, maturation rates, IQ, etc.)” This isn’t “more corroboration” for Rushton’s long-dead theory; nor is this evidence that blacks have longer penises. I don’t understand why people make broad and sweeping generalizations. It’s one country in Africa that complained about smaller condoms from a country in East Asia, therefore this is more corroboration for Rushton’s r/K selection theory? The logic doesn’t follow.

Asians have small condoms. Those condoms go to Africa. They complain condoms from China are too small. Therefore Rushton’s r/K selection theory is corroborated. Flawed logic.

In sum, Lynn (2013) didn’t verify Rushton’s theory regarding racial differences in penis size and I find it even funnier that Lynn ends his article talking about “falsification’ stating that this aspect of Rushton’s theory has survived two attempts at falsification, therefore, it can be regarded as a “progressive research program“, though obviously, with the highly flawed “data” that was used, one cannot rationally make that statement. Supposed hormonal differences between the races do not cause penis size differences; even if blacks had levels of testosterone significantly higher than whites (the 19 percent that is claimed by Lynn and Rushton off of one highly flawed study in Ross et al, 1986) they still would not have longer penises.

The study of physical differences between populations is important, but sometimes, stereotypes do not tell you anything, especially in this case. Though in this instance, the claim that blacks have the longest penis lies on shaky ground, and with what evidence we do have for the claim, we cannot logically make the inference (especially not from Lynn’s (2013) flimsy data). Richard Lynn did not “confirm” anything with this paper; the only thing he “confirmed” are his own preconceived notions; he did not ‘prove’ what he set out to.



  1. EMuse says:

    1. The Zimbabwe Ministry of Heath would have specified what size they wanted
    2. If one comment is correct (, the Minister begged for free Chinese condoms
    3. Contra Macdonald, condom size pertains to girth not length


    • RaceRealist says:

      Good points. Those who still push the falsified r/K paradigm don’t care, though. The news story ‘corroborated’ Rushton, supposedly. That’s all they need to trumpet their falsified racial paradigm.


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