mmalabanan
Do you ever wonder why humans, unlike other mammals, don’t possess a bone in their joystick?
Believe it or not, it has something to do with the human’s preference for monogamous relationships.
Also known as baculum, the penis bone is believed to have evolved between 145 and 95 million years ago to help mammals have sex for a longer period of time. This was particularly observed among mammals in animal populations with high levels of sexual competition.
In a study published in Proceedings of the Royal Society B, researchers found that the bone gave structural support so that males can last longer during intercourse. That’s because stiff competition among multiple rival males drove them to have longer sex sessions in order to prevent other males from fertilizing their preferred female.
It is believed that humans possibly lost the baculum around 2 million years ago, a time when monogamous single-partner relationships was preferred by majority of humans. Scientists believe that when a male and female only have sex with each other, postcopulatory competition between males is decreased. Consequently, the length of sexual intercourse no longer matters.
“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,” lead author Matilda Brindle said.
The research also yielded some interesting revelations. Apparently, two of our closest cousins, the chimpanzees and bonobos have a baculum measuring 6 millimetres long. Researchers noted that the primates only have sexual intercourse for an average of 7 seconds for chimps and 15 seconds for bonobos.
“After the human lineage split from chimpanzees and bonobos and our mating system shifted towards monogamy, probably after 2 million years ago, the evolutionary pressures retaining the baculum likely disappeared,” said co-author Dr. Kit Opie.
“This may have been the final nail in the coffin for the already diminished baculum, which was then lost in ancestral humans.”
