Racial and ethnic variation in penis size, pt. 1: some background

A few years ago, a "World Penis Size Map" [1] citing a website containing largely made-up numbers [2] entered widespread circulation. Despite being an obvious and inept hoax, it has continued to take in various people, including the press, some economist [3], and Richard Lynn [4]. I started writing up a post at the time, but never bothered to finish it.

Most recently, a presenter at the 2015 London Conference on Intelligence has attempted to defend this hoax data, claiming:

  • Lynn (2013) attempted to resolve the controversy by obtaining data from the World Penis Website, which listed average national penis lengths based on various sources. Using this, Lynn extended Rushton?s model, based on this, to other races, and found that their average penis sizes differed as Differential K would predict.
  • This paper was ridiculed, most notably by a psychologist blogger called Scott McGreal, who pointed out various minor mistakes on the World Penis Website, insisting all its contents was suspect and not properly reviewed
  • As I am researching a book that extends Rushton?s theory to 12 races, I was very interested in Lynn?s penis data. It occurred to me that we can test the validity of Lynn?s national penis lengths by seeing if they correlated with other national measures androgen in the expected direction.
But the website does not just feature a few "minor mistakes". Most of the data is simply made up. One can't "validate" made-up numbers by attempting to correlate them with other putative markers of androgen exposure.

Brief overview of the hoax website

"World Penis Average Size Studies Database" contains a table purporting to show "Avarage [sic] penis size" for each of over one hundred countries. "This website provides information offered by trusted research centers and reports worldwide", the subheader assures us. Looking at the "Data Sources" page as it appeared in 2011 [5], one finds a handful of references to relevant academic studies and a larger number of references included to appear superficially relevant to casual visitors but not actually containing any relevant data. No plausible internet sources for the alleged "self-reported" data were given and even for the purported "measured" averages published sources are almost never available. It's clear the overwhelming majority of the numbers were simply made up by the creator of the site. For most countries, the data simply does not exist. Even where actual data does exist, the site creator appears to prefer making up numbers. For example, he creates a "self-reported" number for Italy instead of relaying the results of a published 3,300 person Italian study he lists in his references. Finally, on the contact page, in an amusingly bad attempt at defusing suspicion and deflecting questions about sources, we see "Studies results are summarized in this website; however some sources can not be mentioned, due to diplomatic dispute and reputation of scientific institutes."

The open dishonesty of the "worldpenissize" site creator is also on display in his use of the following doctored image [6]:

The chart as it appears at its original source [7]:

The directions in which the website creator chooses to fake numbers may also provide some insight into his motivations. My immediate impression in 2011 was that he is some sort of mestizo. A more credulous Richard Lynn noted the same pattern in the fake data [4]:
The New York City study shown in Table 2 gives data for penis length for Hispanics compared with European Caucasoids, and the 113 nation study shown in Table 3 gives data for penis length for Mestizos in Latin America compared with European Caucasoids. In both data sets, penis length is greater for Hispanics/Mestizos than for European Caucasoids at 6.5 inches and 6.1 inches, respectively, in the New York City data, and 15.99 cm and 14.51 cm, respectively, in the 113 nation study.
The "113 nation study" is the set of made-up numbers discussed earlier. The "New York City data" is yet another fictitious data set formerly appearing on the "worldpenissize" website. (It seems to have been subsequently removed.)

General considerations on penile anthropometry

I'd expect the major issues here to be fairly obvious to most people (though perhaps not, given the credulity with which many received the idea of having a dick-measuring contest based on alleged results of hundreds of studies of non-existent provenance invented and thrown on a map by an unknown person). Because there are many possible variations on exactly what the target being measured is, how it's measured/reported, etc., results of various studies will not necessarily be directly intercomparable. If you're in need of more explicit detail here, Jewish web magazines Slate and Salon have you covered.

Kent Sepkowitz on "The inexact science of penis measurement" [8]:
The penis elongation industry has created the need for careful studies to determine who should and should not be considered for "augmentation." Urologists worldwide are busily stretching and measuring and reporting their findings. Most recent articles hail from outside the United States—the Italians, Turks, and Greeks seem especially engaged. There is a fascination with determining the dimensions of newborn boys of different ethnic pedigrees. From Ben-Gurion University in Israel, we have "Clitoral and penile sizes of full term newborns in two different ethnic groups" (Jewish and Bedouin), and from Singapore General Hospital, "Penile length of [Chinese, Malay, and Indian] newborns in Singapore."

The modern story begins in 1942, when American researchers W.A. Schonfeld and G.W. Beebe set out to define normal genital growth and variation in males from birth into their 20s. They measured penis length (using a wooden ruler), circumference (using a series of graded rings), and testis volume (using an instrument called the orchidometer) in 1,500 volunteers of various ages. But it wasn't so easy. And the difficulties that the first wave of researchers encountered continue to render our latter-day interpretation of penis studies a risky business.

First off, what do you measure—from where to where? What configuration should the penis be in—erect or flaccid? What about room temperature? (George Costanza was on firm scientific ground when he lamented the grim reality of shrinkage.) Furthermore, who should do the measuring? Self-reported measurements are more, um, forgiving than size determined by a disinterested medical professional, by half an inch or more. The methodological problem is on display in online penis measurement surveys like altpenis.com (900,000 and counting) or sizesurvey.com. More importantly, it confounds the most frequently quoted study in the field, by Alfred Kinsey. The great sex researcher of the 1950s interviewed 18,000 men, 3,500 of whom mailed back cards on which they recorded their own length and circumference in both erect and flaccid states. (Click here for a recent reanalysis of Kinsey's data that compares the penis length of heterosexuals and homosexuals.)

The 1940s researchers introduced another problem. After much analysis and reanalysis, they concluded that measurement of neither the flaccid nor the erect penis could be reliably reproduced. So, they created a new approach: They measured the flaccid but stretched penis. Although statistically validated and still used in most studies, this method of measurement creates a different conundrum, because the maximally stretched flaccid penis simply does not exist in nature. Outside the doctor's office, no one has ever seen one. Who cares how long the average one is? Plus, the stretch-'em approach has led to some bitterness in the literature, over a study by French researchers who stretched the penises of their subjects three times and reported suspect lengths—on average, more than an inch longer than the rest of the pack. Cheaters.

So, after more than 60 years, and thousands and thousands of penises measured for the cause, we still don't know who should measure, what to measure (erect, flaccid, or stretched), where to measure from (the pelvic bone to the tip of the glans is the usual itinerary, but some researchers push the ruler against the pubic bone to give obese people a break, or don't allow for the gain in length of curvature), or how many measurements are enough to assure an accurate result.

But wait—there's a hidden benefit here. The lack of resolution teaches readers to scrutinize how a study is conducted. The literature on penis size—found in such journals as The Archives of Sexual Behavior, European Urology, and The Journal of Pediatric Endocrinology and Metabolism—makes everyone an expert in methodology. In this field, readers are wired for the slightest perturbation.
 Debby Herbenick in Salon [9]:
As far as I can tell – being a scientist who studies sexual behavior and penile dimensions specifically – there has not been a downward trend in men’s penile length. In other words: I know my way around the penis and I haven’t yet found evidence that men’s penises have been shrinking on a global scale. For one thing, there are few data on adult male penis size from 50 or 60 years ago (Alfred Kinsey’s team published some data, though the response rate was relatively low), so historical comparisons are difficult to make. [. . .]

At the group level, the size of a man’s erection has also been linked with a higher Body Mass Index, which the chacha brief mentions (several studies have found this to be the case). This is likely for two reasons: 1) Men with a great deal of abdominal fat may find that their fat obscures part of their penis; and 2) many but not all men who are obese also have other health issues such as cardiovascular health problems or diabetes, each of which can contribute to erectile problems.

A note on one of Rushton's sources

Rushton claimed [10]:

We averaged the ethnographic data on erect penis and found the means to approximate:
Orientals, 4 to 5.5 in. in length and 1.25 in. in diameter;
Caucasians, 5.5 to 6 in. in length and 1.5 in. in diameter;
blacks, 6.25 to 8 in. in length and 2 in. in diameter.
As I've pointed out before, rather than representing any "averaging" of "the ethnographic data", these numbers appear to be drawn directly from a single 19th-century book, supposedly containing the observations of a lone "French Army Surgeon" [11]. Detractors of Rushton at one point dismissed this book as "nineteenth-century anthroporn". As it turns out, they were probably more right than they knew (on this point, if not necessarily on much else). The pseudonymous French author "Jacobus X" seems to have been not a surgeon but a lawyer (Louis Jacolliot, who was apparently more prominent as an occult fantasist) and the English publisher, Charles Carrington, was in fact a literal pornographer. So Untrodden fields of anthropology is not a credible source even as concerns one observer.


[1] The Penis Size Worldwide (country) http://www.targetmap.com/viewer.aspx?reportId=3073

[2] World Penis Average Size Studies Database  http://www.everyoneweb.com/worldpenissize/

[3] Tatu Westling. Male Organ and Economic Growth: Does Size Matter? 2011. http://hdl.handle.net/10138/27239

[4] Richard Lynn. Rushton’s r–K life history theory of race differences in penis length and circumference examined in 113 populations. Personality and Individual Differences. Available online 12 March 2012. http://dx.doi.org/10.1016/j.paid.2012.02.016

[5] http://web.archive.org/web/20110406010559/http://www.everyoneweb.com/worldpenissize/ The website has since been changed/updated, but the pattern appears to remain more or less the same. For example, the cited "data sources" now include the Richard Lynn paper -- which contains no original data but merely cites http://www.everyoneweb.com/worldpenissize/ as its main source. There are also now a few web links to things like "Self measurement database @ measureyourcock.tumblr.com Retrieved on 2012-01-10", which I have no interest in exploring but which I can be pretty sure could not combine to account for the volume and breadth of data supposedly available to the website creator.

[6] I don't immediately locate this doctored chart on the current version of the website, but I know it was there in 2011; and based on archive.org it appears to be one of the initial bits of fabricated data the creator started his website with in 2009: http://web.archive.org/web/20090119052005/http://everyoneweb.com/worldpenissize/

[7] The Definitive Penis Size Survey Results. Sixth Edition. http://www.sizesurvey.com/result.html 

Note: This image has been online since at least 2001: http://web.archive.org/web/20010808092714/http://www.sizesurvey.com/result.html

[8] Kent Sepkowitz. On the Matter of Size: The inexact science of penis measurement. Feb. 13, 2006. http://www.slate.com/articles/health_and_science/medical_examiner/2006/02/on_the_matter_of_size.html

[9]  Debby Herbenick. No, really: Penises are not shrinking. Rush Limbaugh is wrong about that. But here's the long (and short) of what science really does tell us about size. Sep 28, 2012. http://www.salon.com/2012/09/28/no_really_penises_are_not_shrinking/

[10] Rushton, J.P. & Bogaert, A.F. (1987) Race differences in sexual behavior: Testing an evolutionary hypothesis. Journal of Research in Personality 21(4): pp. 536-7 http://dx.doi.org/10.1016/0092-6566(87)90038-9

[11] Untrodden fields of anthropology : observations on the esoteric manners and customs of semi-civilized peoples, being a record of thirty years experience in Asia, Africa, America and Oceania. Jacobus X / A French Army Surgeon. Paris : Librairie de Medicine, Folklore et Anthropologie, 1898.


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