While human’s closest relatives chimps have penis bones, apparently men don’t need one because sex doesn’t last as long. According to scientists, it comes down to our tendency to be monogamous and lack of competition when it comes to finding a partner.
The penis bone, or baculum, first evolved in mammals around 145 and 95 million years ago and has been described as “the most diverse of all bones,” varying in length, width, and shape across primates and carnivores according to new research from University College London.
Scientists set out to establish why humans do not have penis bones when both ancestral primates and carnivores do.
The new research shows prolonged intromission – or penetrative sex for longer than three minutes – is linked to the likelihood of the penis bone evolving in a species. They also discovered that the longer sex lasted, the long the penis bone was likely to be.
And, in species where sexual competition between males is high, the more likely the mammals would have a longer baculum.
The study’s lead author Matilda Brindle said: “Our findings suggest that the baculum plays an important role in supporting male reproductive strategies in species where males face high levels of postcopulatory sexual competition.
“Prolonging intromission helps a male to guard a female from mating with any competitors, increasing his chances of passing on his genetic material.”
She said that when any cultural aspects of sex are removed, and a male’s aim is solely to ejaculate, humans last for a shorter period of time in the sack.
She told the Independent: “The human intromission duration tends to be below two minutes, which most people wouldn’t expect.”
Compared to the aye-aye, a nocturnal lemur, who can go at it for an hour at a time and has a very long baculum.
Chimpanzees have small bacula, measuring between 6-8mm, and a short intromission duration, approximately seven seconds.
The bad news for men is that chimps mate with multiple females and have loads of competition, which the researchers say helps explain why they have retained a penis bone.
Well, it might not be good news for us men, but at least we beat the chimps in duration.