A new study published in PLOS Biology reveals that men are far more preoccupied with penis size – both their own and others’ – than women are. Researchers found that male participants consistently rated other men as more physically and sexually threatening as penis size increased, while women’s ratings of sexual attractiveness showed diminishing returns beyond a certain point.
Evolutionary Roots of Male Anxiety
For years, scientists have puzzled over why human penises are proportionally larger than those of most other primates. Theories range from attracting mates to intimidating rivals, but the new research provides the first experimental evidence that men view penis size as a direct indicator of both fighting ability and sexual competitiveness. The study suggests this obsession isn’t merely a cultural quirk; it’s likely an evolutionary adaptation.
The Study: How It Worked
Researchers at the University of Western Australia presented over 600 men and 200 women with computer-generated male bodies of varying sizes and shapes. Participants were asked to assess these figures based on intimidation levels (for men) and sexual attractiveness (for both sexes). The key finding: men consistently rated larger penises as more threatening, with no apparent upper limit on how intimidating they found them. Women, while also showing a preference for larger sizes, hit a point of diminishing returns.
Why This Matters
This study offers insight into why human penises evolved to be larger than those of other primates. According to co-author Michael Jennions, the results suggest that size is a sexual ornament to attract females, but also a status symbol to ward off male rivals. The research implies that the human penis serves a dual purpose: reproduction and social dominance.
“While the human penis functions primarily to transfer sperm, our result suggests its unusually large size evolved as a sexual ornament to attract females rather than purely as a badge of status to scare males,” said Jennions. “Although it does both.”
The study underscores how deeply ingrained competition and sexual selection are in human psychology, particularly among men. It also highlights the disconnect between male anxieties and female preferences, suggesting that much of the obsession with size is driven by male insecurities rather than universal attraction.
