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Since the dawn of the fragile male ego, a simple phrase was born alongside it – ‘size doesn’t matter’.
But this may be untrue.
A new study from UWA has found that penis size does matter, with females rating larger penises as more attractive and males considering men with larger penises more intimidating or sexually competitive.
So why does it matter and what sort of an experiment can tell us this?
DAR-WINNERS AND LOSERS
Before we get into how the experiment was conducted, it’s important to understand why this research was done in the first place – and it’s all to do with evolution.
Evolution has ensured that our bodies are built to survive and outlast. We have colour vision to detect visual threats and opposable thumbs to hold things.
But compared to other primates, humans have a big penis to body size ratio, which made evolutionary biologists curious.
Credit: Dan Kitwood/Getty Images
Sexual selection has been a leading theory. But given some ethical research boundaries and enormous variety in human bodies, coming up with an experimental design to test this idea wasn’t easy.
BIG D*CK ENERGY
To overcome what researchers call ‘natural covariation among traits’ (otherwise known as ‘no two penises are the same’), they computer-generated images of males. Then they manipulated penis size, height and body shape.
343 images were shown to over 800 heterosexual study participants, who rated the figures based on one of three questions.
Females were asked to rate how sexually attractive the figure was. Males were asked to rate how jealous they would feel if the figure was talking to their partner or how threatened they would feel if the figure picked a fight with them.
For all questions, figures that were taller and had a V-shaped body and large penis were selected.
Credit: Aich et al., 2025, PLOS Biology
This research finds that both female choice and competition between males is a strong theory for humans having large penises compared to other primates.
A PEACOCK EQUIVALENT
While it seems an odd thing to study, understanding what drives human evolution has fascinated us for years.
While the main function of a penis is sperm transfer, it appears our ancestors needed a larger penis to attract a female mate. A large penis in humans is apparently the peacock equivalent of a massive, feathered tail.
For anyone with a penis who might be feeling a little blue after reading this, just remember, we wear clothes now.
