The Science Behind Why Size Matters: Understanding Human Attraction
When it comes to physical attraction, a recent study published in PLOS Biology has reignited the age-old debate about whether size matters. Dr. Upama Aich from the University of Western Australia and her research team have confirmed what many suspected: women generally do find larger male genitalia more attractive. This finding emerged from their broader research question examining why human males, relative to body size, possess significantly larger penises than other great apes—especially considering that the primary biological function is simply reproductive. The researchers discovered that this evolutionary development likely served dual purposes: attracting potential mates and signaling dominance to potential rivals, similar to how deer antlers or a lion’s mane function in the animal kingdom.
The study’s methodology was comprehensive, involving over 800 participants (600+ males and 200+ females) who were asked to rate computer-generated male figures that varied in height, body shape, and penis size. Female participants evaluated sexual attractiveness, while male participants assessed how threatening these figures appeared both as potential physical opponents and as sexual competitors. The results painted a clear picture: women consistently rated taller men with V-shaped upper bodies and larger genitalia as more attractive, though researchers noted there was a point of diminishing returns where additional size no longer enhanced attractiveness. Meanwhile, male participants perceived well-endowed figures as more formidable rivals both in fighting ability and sexual competition, suggesting that genital size serves as a visual signal in male-to-male assessment as well.
From these findings, the research team developed a compelling evolutionary theory. They suggest that before clothing became common, humans walked upright with their genitalia visible—creating a natural “display” that could communicate information to both potential mates and rivals. This visibility meant that genital size could function as a status symbol and attractiveness indicator simultaneously, influencing both intra-male competition and female mate selection. However, the researchers emphasized that sexual selection through female preference likely played a significantly greater role in the evolution of penis size, as the effect on attractiveness ratings was “four to seven times higher than its effect as a signal of fighting ability,” according to their published results.
Professor Michael D. Jennions, a co-author and Evolutionary Biology expert at Australian National University, summarized their conclusions succinctly: “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, although it does both.” This dual-purpose evolutionary advantage helps explain why humans evolved such distinctive proportions compared to our closest primate relatives. The findings contribute to our understanding of sexual selection pressures and how they shape physical traits across species, particularly those that seem exaggerated beyond mere functional necessity.
The researchers acknowledged several limitations to their work that provide context for interpreting their results. Most notably, the study focused exclusively on physical attributes—penis size, height, and body shape—without accounting for how personality, facial features, or other characteristics might interact with these factors in real-world attraction scenarios. Real human attraction is complex and multifaceted, with physical attributes representing just one component of what makes someone appealing as a potential partner. Additionally, the team recognized that standards of masculinity and attractiveness vary significantly across different cultures and historical periods, making universal claims about preference challenging.
This research offers valuable insights into the evolutionary forces that have shaped human anatomy, but it’s important to view the findings within a broader context of human sexuality and attraction. While the study suggests that size can play a role in initial physical attraction, genuine human connections involve countless other factors including emotional compatibility, intelligence, kindness, and shared values. The researchers’ work helps us understand one aspect of our evolutionary history, but the full spectrum of human relationships remains infinitely more complex than any single physical attribute. As with most scientific studies of human behavior, these findings represent statistical trends rather than individual realities, reminding us that diversity in preferences and relationships remains one of humanity’s most defining characteristics.
