Priapic proportions: fact, fantasy, and phallusy.
Penis size figures prominently in discussions of the evolutionary biology of human reproduction and mate choice. Yet serious research lags well behind a pop culture driven by myths that few bother to question. A reappraisal yields some unexpected insights.
Mythologizing human penis size
Perhaps Desmond Morris did not start everything, but his 1967 book The Naked Ape definitely fanned the flames. Introducing the male of the species, he wrote: “He is proud that he has the biggest brain of all the primates, but attempts to conceal the fact that he also has the biggest penis, preferring to accord this honour falsely to the mighty gorilla.”
Other biologists have endlessly repeated that claim over the past 50 years. Witness Steve Jones in The Language of Genes (1993): “There is also the question — as yet unanswered by science — as to why, in penis size, man stands alone.”
The myth flourished with ever-growing hyperbole. The Amazon blurb for Jared Diamond’s 1997 book Why is Sex Fun? rhetorically asks: “Why is the human penis so unnecessarily large?” Unnecessarily? Is that why we see hordes of men seeking penis reduction?
For hard facts, let us turn to reproductive biologist Alan Dixson’s comprehensive studies of the primate penis. In 2009 and 2012, he published information for 48 primate genera, listing the following erect penis lengths in inches: 3.4 in orangutan, 2.6 in gorilla, 5.8 in chimpanzee, 6.8 in bonobo and 6.6 in men. A male bonobo accordingly has a longer penis than a man.
Dixson cited human penis size from the impressive sample of 2310 summarized by Gebhard & Johnson (1979). But 12 smaller samples listed by Promodu and colleagues in 2007 indicate a cross-cultural average of only 5.7 inches. So broader comparison suggests that a male chimpanzee also has a longer penis than a man.
Nevertheless, the human penis is the widest compared to other primates. Indeed, average girth, flaccid or erect, is close to average length.
Hard data also conflict with other myths regarding human penis size. Strikingly, no clear differences between human populations are evident in the table of Promodu and colleagues or in the extensive online compilation by EthnicMuse. Contrary to repeated claims, African men do not have a particularly large penis, although there is a trend for Asian men to have somewhat smaller-than-average penis lengths (possibly reflecting smaller average body size). Also contradicting popular belief, a 2002 study by Shah & Christopher found no significant correlation between penis size and shoe size.
