Look closely at your friends, family and even strangers. Spot anything strange?

Ignore any large noses or unusually-shaped brows. Instead, look at their hair – or rather, the lack of it.

It might not seem strange, because we are used to having relatively little hair covering our bodies. But when we compare ourselves to the rest of the mammals, and our closest living ape cousins, it is downright bizarre that we are the only large-bodied mammal with so little of it.

Unlike hairy chimpanzees and bonobos – and all other primates – most of our skin is on display. We have evolved this way, even though fur is beneficial: it insulates and protects the skin, and in some cases acts as a useful camouflage. So if it is so advantageous, why did we lose so much of it?

It was Charles Darwin who first taught the public that humans are descended from an ape-like ancestor. He also wondered why we had so little hair.

Something must have created an evolutionary pressure for these hominins to lose their fur

“No one supposes that the nakedness of the skin is any direct advantage to man; his body, therefore, cannot have been divested of hair through natural selection,” Darwin wrote in The Descent of Man.

He proposed that we lost much of our fur due to sexual selection: we preferred hairless mates, and that is why hairlessness became common.

But that cannot be the whole picture. Before a preference for hairlessness began, we first had to start losing hair.

Our earliest human-like ancestors, known as hominins, were ape-like. For them, fur would have been useful, keeping them warm on cold nights.

Something must have created an evolutionary pressure for these hominins to lose their fur.

A few million years ago, there were several hominin species roaming the Earth. These included the famous fossil known as “Lucy”, an Australopithecus afarensis from 3.2 million years ago.

Read more