does size really matter? just ask evolution…
A while ago, I wrote a post about some of the evolutionary mysteries presented to us by women’s breasts, pointing out how sexual selection doesn’t completely explain their sizes and shapes. Today, we’ll take a look at another possible product of sexual selection, one that seems to be a little more clear cut. I’m talking about the penis of the human male, the biggest in length, girth, absolute size and in proportion to the body when put up against that of all other ape species. But how did it get that way? Well, if evolutionary psychologist Carole Jahme is right, then the blame rests with you ladies. Thanks to your preferences in mates, the human penis grew in size to become more flexible, loosing the small bone of its evolutionary relatives. There weren’t many advantages to this change in physiology other than pleasing the female eye, among other things, but that’s all that matters from an evolutionary standpoint since without a shot at reproduction, your line will go extinct…
Of course there’s a bit more to it than that. Sexual selection is the same reason why peacocks have giant fans for tails, making them a potential target for fast predators. While it would seem that males with an extravagant plumage are easier to find, chase, and catch would branch off into something less conspicuous and far more subtle to avoid predation, the peahens prefer a male who can keep his outrageous plumage safe from both predators and competitors. Same applies to male lions whose dark, thick manes attract more females, and a giant deer which went extinct at the end of the Ice Age, the Irish Elk, which had a pair of titanic antlers to attract potential mates and intimidate rivals. Human penises followed the same selective pressures, as we see with typically male contests in which penis size serves to establish the perception of fertility and sexual athleticism in a bid to attract women and intimidate other men. Likewise, since human sperm compete to fertilize eggs, a larger set of testicles and higher sperm production would help fertilize more eggs and produce more offspring who inherit the sexual characteristics that should give them at least as good of a shot at reproducing as their parents, assuming they’ll get to puberty; which at one time was no guarantee.
So what about the often heard male question regarding whether he’s adequately endowed to attract women’s attention? If sexual selection can explain why humans have the genitals they do today, could it provide at least a couple of clues there? Well, as a matter of fact, it can. While for many young men the idea of adequate size comes from adult entertainment, porn is really a bad source of information here because it portrays a narrow slice of the population based on very subjective criteria. Instead, we can look at the distribution of penis sizes as measured by condom maker Ansell, which shows that nearly 25% of males have a penis which measures between 5.5 and 6 inches. After the 6 inch mark, there’s a rapid drop-off in sizes and males endowed with 7 or more inches make up just 5% of the population compared to the 70% of males with a length between 5.5 and 7 inches. What does that tell us? If women preferred very large penises, we would expect to see either a more even distribution of male endowments between 5.5 and 9 inches (the largest size recorded by the survey, just under 0.1% of the group), or a skew towards the larger end of the scale. This indicates that the preferred size for human females is in the 5.5 to 7 inch range, primarily between 5.5. and 6.5 inches. Seven inches and over is more of an oddity, the likes of which we tend to see in porn.
On a side note though, it might be interesting to look back after a number of generations to note if penis sizes increased in any meaningful way thanks to the influence of pop culture. My guess would be that constraints on the male anatomy will stay in place for quite a while since there’s more to sex than just a certain penis size. A male at the top 1% of the size distribution chart might actually cause a lot more pain than pleasure. After all, in this case of sexual selection it’s about what women want, not necessarily what males think will intimidate the competition and make a statement to a potential mate, and the size distribution shows that quite well…
[ illustration from a Thai contraceptive ad ]
Female preference is hardly the only factor driving “sexual selection”.
Aren’t there numerous cross-species studies showing a strong correlation between penis size and male sexual coercion (aka rape), at least among primates?
Evolution tends to favor whatever works, not what’s morally right nor what makes individuals happy.
Aren’t there numerous cross-species studies showing a strong correlation between penis size and male sexual coercion (aka rape), at least among primates?
If there are, I’m not aware of them, nor could I find them. True, sexual selection isn’t a simple case of whatever females like being propagated and competition for mates is also a very powerful driving force, as noted in the post. But female preference is very, very influential because if you can’t find a mate, your genes aren’t passed on and the particular feature of your anatomy doesn’t propagate.
It’s fascinating, although not unexpected, that an article about sexual selection by females is driven by the premise that the size of the male penis not only matters, but takes precedence. Very well written; precise, even bordering on the clinical, the article misses the point altogether.
Penis size, beyond consideration of reliable sperm delivery, is a matter of recreational preference, for both parties. A woman’s sexual selection, for breeding purposes anyway, is based almost exclusively on whether or not she believes the male in question can and more importantly, will, protect and provide for her and for their progeny going forward. The state of modern birth control – from 6” condoms to monthly hormone control to morning after spermicides for the forgetful, makes breeding almost entirely the female’s choice. The penis is the last tool she employs to get what she wants – a child.
The candidate tryouts, however, are legendary. #thatisall
I couldn’t find anything to support my own point either, but I did run across these:
“… monogamous penises tend to be small (the faithful owl monkey has a member no more than a fortieth of its body length when limp) and promiscuous species tend to have the largest organs. Almost all primates have a baculum, a penile bone …” – Steve Jones, Y: The Descent of Men, pg 178
“The bonobo male’s genitals are among the largest in the primate world. Certainly relative to body size (and probably absolutely as well), this ape’s testicle size and erect penis length surpass those of the average human male, until recently believed to be the champion.” – Frans de Waal, Peacemaking Among Primates, pg 199
Amazingly, a 1978 textbook called Sex, Evolution & Behavior has no index entries for “penis”, “genitals”, “rape” or “intercourse”.
“The survey requiring women to rate male attributes they found sexiest reported only a 2 percent preference for penises, compared to a 39 percent interest in buttocks; the women were more attracted to broad shoulders and buttock shape than large penis size. … The vagina is, believe it or not, a very hostile place for sperm; it is acidic, a veritable obstacle course or torture chamber so full of pitfalls that most of the time not a single of the hundreds of millions of sperm ejaculated survive. A penis that reaches the back walls of the vagina therefore has an advantage over one that ejaculates its contents further from the egg.” – Lynn Margulis and Dorion Sagan, Mystery Dance: On the Evolution of Human Sexuality, pp.163- 164
I think the whole idea help blown way out of hand since the introduction of the internet,, more access to porn clips has sent the attitude of individuals crazy,, we should be happy with what we have been blessed with and not try and change our bodies to conform to some crazy illusion of the perfect body,, well thats my rant lolol
Don’t you think insecurity about one’s penis size explains the 2000+ years of patriarchy that has kept women subservient and unable to choose her mate? Sex before marriage is taboo because a women will be able to experience the sexual prowess of her mate and she could choose to leave. Today, many western women have a chance to choose, and the constant proliferation of sexual harassment is probably a sign that many men resent that they are not top choice.
Annie, was that a question or a statement? It certainly sounds like a statement to me, and one that doesn’t seem to be backed up by anything other than your personal opinion…