A new study by Australian researchers shows that well-endowed guys are more attractive to women — but only to a point.
Like other physical characteristics, male genitalia are subject to sexual selection. And in fact, penises have been known to evolve quickly, owing to strong selectional preferences at play.
And indeed, human males are not immune to this, especially when considering our evolution prior to the introduction of clothing. Given our upright posture and a non-retractable penis, it would have been literally right out there in the open for prospective females to assess.
Subsequently, biologists have suspected that the human penis, which is longer and wider than that of other primates, achieved its current configuration on account of sexual selection.
Rating Sexual Attractiveness
To see if this was the case, an Australian team of researchers led by Brian Mautz conducted a study in which 105 heterosexual women ranging in age from 18 to 53 were shown a series of life-size cut-out computer-generated images of variously-sized men, all of whom were shown in a flaccid state. Over 340 different images — which were derived from studies of Italian men — were presented to the women on a movie screen, who were simply told that the study was about measuring “male attractiveness.”
Each participant was shown a random set of 53 figures and were told to rate their attractiveness as potential sexual mates on a scale of one to seven.
The findings have now been published in the Proceedings of the National Academy of Sciences.
What the researchers learned was that penis size does in fact matter to women when evaluating male attractiveness. But this attractiveness depended on other factors as well, including body shape and height.
And in fact, penis size is just as important to women as height; larger penis size and greater height had a nearly identical positive effect on male attractiveness. The researchers also measured a positive effect of penis size on the attractiveness of men with more masculine-shaped bodies, like broad shoulders.
Matt Soniak offers a good summary:
An increase in penis size was also a bigger benefit to attractiveness, and a smaller penis was less of a detriment, to the taller, fitter figures than it was to shorter or potato-shaped ones. For example, a model that was 185 cm tall (about 6 ft) with a 7-cm-long (about 3-in-long) penis got an average score for attractiveness. To get that same score, a model that was 170 cm (about 5'6") needed a penis of about 11 cm (about 4.5 in) in length. Boost the taller guy's penis by just about centimeter, and the shorter guy needs double that to keep up and get the same attractiveness score. After that, the shorter male pretty much can't continue to compete. To really reap the benefits of a big penis, a guy needs to be attractive in the first place, Mautz says. If he isn't, even the biggest penis in the world won't do him that much good.
But the researchers also discovered that big can be too big. Once penis length surpassed a certain point — about 3 inches (7.6 cm) — attractiveness began abating.
The researchers have presented their paper as further proof that female preference has in fact driven the evolution of larger penises in humans.
Moreover, the study shows that there may come a point for women when extreme features violate an aesthetic sense of normal physical proportionality. Overly exaggerated features — even ones that are important to attractiveness — cease to be appealing because they may indicate a problem from the standpoint of reproductive fitness. It would be interesting to see a follow-up study determining if and when broad shoulders and height cease to be attractive.
Room for Improvement
Though interesting, and perhaps a bit revealing, the study is not without its problems.
First, there's a risk of overstating these findings. Taken overall, body shape accounted for about 80% of the variation in attractiveness scores, penis size about 6%, and height about 5%.
And as the researchers themselves admit, it’s possible that the female participants were using their previous sexual experiences to infer a link between penis size and sexual pleasure. In other words, they weren’t necessarily physically attracted to the men, but were rather consciously or unconsciously biased towards the well-endowed men based on previous sexual experiences (which, interestingly, could still be said to be a form of attraction).
Also, the study did not look into sexual attractiveness as it relates to erect penises; the paper strictly looked at “precopulatory sexual selection” on the “role in the evolution of genital traits.” It’s not unreasonable to suggest that copulatory sexual selection also plays an important part in all of this.
Lastly, the study suffers from cultural biases. The research should have included women from other countries and cultures, especially indigenous cultures where full clothing isn’t typically worn.
Check out the entire study at PNAS: “Penis size interacts with body shape and height to influence male attractiveness.”