We are the odd ones out. Almost every other mammal wears a coat. We wear a crown.
Somewhere between one and two million years ago, our distant relative Homo erectus stood up, grew longer legs and shorter arms, and started walking and running for hours across the hot African savannah. That created a problem. Overheating.We are the odd ones out. Almost every other mammal wears a coat. We wear a crown.
The solution was clever. Lose the fur, so that sweat can evaporate and carry the heat away. Less body hair also meant fewer places for ticks, lice and fleas to live. A hairless body was a cooler, cleaner body.
But the scalp was different. It took the full force of the equatorial sun, so it kept its hair.
That is the biology, and it is only half the story. Because the moment we had a crown, we started doing things with it that have nothing to do with keeping cool. We shaped it. We covered it. We cut it off as a sign of devotion. We dyed it to say who we were.
And here is the part I find most interesting. The same genes that gave us this strange arrangement also gave us the enormous range of hair we see today: straight, wavy, curly and tightly coiled, in every colour. Each one is a small piece of evolutionary history, carried on our heads.
So, the next time you look in the mirror, remember what you are looking at. Two million years of adaptation, sitting on top of your skull.