Why Are Human Penises So Big But Balls So Small?

Ape Human Penises

Not much separates us from our closest primate relatives. A little more brain, a little less body hair. But when you get into it, there are still some serious questions about the differences between men and apes. One that concerns us is simple: why are human penises big and our balls small, while other primates have small penises and big balls?

A fascinating article in the International Business Times delves deep into this mystery. The largest of gorillas, who outweigh us several times over, have penises that are about two and a half inches long. Alternately, a chimpanzee’s testicles weigh as much as a third of its brain! Scientists believe that our unique mating habits caused us to evolve in this very specific direction.

It all comes back to how many females an individual male is supposed to service. Chimpanzees, who mate with numerous women, have to have enormous balls to generate the sperm necessary to do so. Humans, who have essentially settled into a monogamous culture, don’t. Our balls just need to make enough to make a new baby every day at most. As for the penis thing, monogamous species typically have larger but less interesting (ie no bumps or ridges). It’s an interesting article and very much worth reading.