British researchers think they’re closer to an answer to why human males don’t have penis bones, even though their close cousins, chimpanzees, have them.
“Monogamy may have done away with the penis bone,” said Matilda Brindle of University College London, who led the study published in the journal Proceedings of the Royal Society B: Biological Sciences.
Humans have something that chimpanzees don’t have: marriage.
Most human societies are either monogamous, or, if multiple mates are allowed, it’s one man who is allowed to mate with more than one woman.
So they don’t need to worry as much about mate competition.
Penis bones help males keep things going a little longer during mating — helping to ensure that they father any resulting offspring.
Researchers were crunching numbers trying to figure out precisely when and why the penis bone – whose scientific name is baculum – evolved.
“We found that it first evolved after placental and non-placental mammals split, around 145 million years ago, and before about 95 million years ago,” Brindle said in a telephone interview.