The new study examined the evolutionary progression of the baculum, or penis bone, in a variety of primates, who developed the bone 50 million years ago. After that, the baculum lengthened in some species, shortened in others, and for human beings, went away altogether.
The length of the baculum corresponds to the duration of a primate’s mating session - the longer they bone, the longer their bone. And a longer mating period was necessary for ancient guys to pass along their genes, lest another dude mate with their lady right after they finished.
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When human beings stopped swinging and settled down, the baculum went the way of the dodo bird, as it was no longer a necessary appendage for a guy to pass on his genes. (Chimpanzees, for comparison, have a baculum the size of your fingernail.)
Before you get jealous of your monkey relatives, realise that adult male gorillas only have 1.5-inch penises, despite their bonus baculums.
Australian researchers think human beings conquered the penis pyramid because evolutionarily speaking, women were into guys with longer schlongs.
This article was originally published on MensHealth.com