Why the human penis is unusually large compared to that of other primates is a long-standing evolutionary question. New findings suggest that female choice and male-male competition have jointly favored larger penis size, greater height, and more V-shaped bodies in men.

Abstract

**Why the human penis is unusually large compared to that of other primates is a long-standing evolutionary question**. Sexual selection, through female mate choice and male-male competition, is a likely driver, but confirming this is difficult due to natural covariation among traits. The solution is to experimentally manipulate focal traits to identify targets of selection. Using 343 computer-generated male figures that varied in penis size, height and body shape, we experimentally tested how these traits influence perceived attractiveness and fighting ability. Over 800 participants—both male and female—viewed either life-sized (in-person) or scaled (online) animations and rated the figures. Across both settings, selection analyses revealed consistent directional selection favoring taller men with a more V-shaped body and a larger penis. In both surveys, male participants rated rivals with a larger penis as more sexually competitive and physically threatening. To our knowledge, this is the first experimental evidence that males assess rivals’ fighting ability and attractiveness to females based partly on a rival’s penis size. **Our findings suggest that female choice and male-male competition have jointly favored larger penis size, greater height, and more V-shaped bodies in men.**

Citation: Aich U, Tan C, Bathgate R, Blake KR, Capp RCS, Kuek JC, et al. (2026) Experimental evidence that penis size, height, and body shape influence assessment of male sexual attractiveness and fighting ability in humans. PLoS Biol 24(1): e3003595. doi:10.1371/journal.pbio.3003595

0 for three explains why I’m going to die alone and be eaten by my cats.

Give it a few hundred thousand years and we’ll be the fiddler crabs of primates dicks.

>Over 800 participants—both male and female—viewed either life-sized (in-person) or scaled (online) animations and rated the figures.

Ok, to make a claim about humanity, those 800 people better be fully culturally diverse, to represent the entire planet.

>We recruited participants using posters and targeted media posts at the Australian National University (ANU), Monash University, and the University of Melbourne

Yeah, no. This isn’t how this is done. All this study shows is that people in Australia, and *possibly* some cultures where an argument can be made for similar desires, prefer these specific traits today.

will this be published by the BBC?

I like the implications of the chart on perceived fighting ability of a rival: “this guy’s reasonably tall.. but his penis is average at best.. I think I could take him”.. although, interestingly that affect is only when a rival is assessed online rather than in person.. go figure

“Future studies using erect penises remain an avenue for future research to test this claim.” I look forward to seeing part 2.

Maybe some people don’t like imagining wrestling a well hung man and getting occasionally tapped on the head as they switch up wrestling positions?

Penis sizes are a little weird maxing out at 13cm. I’m assuming this is flaccid? 

Correct me if I am wrong… humans stop “open carry” in regards to penis fairly long time ago… so how exactly opposite sex “estimated” the size… to make choice?

Of course all the guys are going to focus on penis size, but the section about how women rated attractiveness makes it clear that body shape contributes much more than penis size. I may be mistaken here, but it also seems to me that women are judging “proportionality” – IE attractiveness is rated more highly when all 3 factors scale up **together.** This means, for example, that a proportionally smaller penis on a short frame would be MORE attractive than a large penis.

This runs counter to the popular male-centric conception that bigger = better no matter the context.

TLDR: hit the gym guys, but don’t forget that this study doesn’t say a single thing about how charm, personality, or sociability factors in to women’s perception of attractiveness.

That’s not what my girlfriend says

So why don’t female primates of other species select for large penis size?

And here I am out there fighting the odds.

Male-male competition… are you taking about sword fights?

Males are also evolving with decreased testosterone levels https://pmc.ncbi.nlm.nih.gov/articles/PMC3182715/

I haven’t read the paper yet, but I just watched a youtube video that talks about how the bronze age bodybuilders (roughly 1890s-1930s) had more of a blocky build and the v-shaped body is really a modern thing that came into being when we invented exercises that isolated the lat muscles.