You can all stop worrying about size, guys. Compared to our primate cousins, humans have the longest penis, a new video explains.
"We find little to worry about," evolutionary biologist Darren Curnoe assures mankind in the video, which bears the cheeky title "How Did We Get Here? Dangly Bits."
According to Curnoe, an associate professor at the University of New South Wales in Sydney, Australia, variation in penis size boils down to the evolutionary pressures associated with reproduction. These pressures vary from species to species.
Take chimpanzees. Male chimps have a medium-sized penis and large testicles capable of producing a lot of sperm. That's because female chimps typically have several partners and there's generally a "sperm war" between the competing males, Curnoe says.
In contrast, male gorillas tend to have a small penis and small testicles. That's because the dominant silverback gets mating privileges with all the females in his harem, Curnoe notes. There's just never been much evolutionary pressure for males to develop an impressive package.
As for us Homo sapiens, Curnoe offers a few theories to explain our relatively big penis and "medium-sized" testicles. One possibility is that walking upright on two feet has made the penis more conspicuous -- and females may be able to choose mates with size in mind. Another possibility is that the penis functions as a sort of "radiator" that releases heat as we walk to keep us cool.
While research continues, man's insecurity persists as well. Curnoe suggests a visit to the zoo to cure that.
"The fact that the male gorilla, all 200 kilos of him, has a small one, never made him question his masculinity," he says.
Of course, we're only human. If you must know how your package compares to other guys', British researchers recently determined that the average human penis measures 3.61 inches when flaccid, and 5.16 inches when erect.
If you're still begging for a case of penis envy, you should know that a New York City man named Jonah Falcon has had his member measured at 13.5 inches.
But even that's no reason to flip out.