Why did we lose body hair?

Why do evolutionary biologists think humans lost body hair?

To dive further into this question, let’s start with a question.

According to evolutionary biologists, what key advantage did humans gain by losing thick hair coverage from the body ?

a) better ability to find a mate

b) reduced chance of infestation with mites

c) better ability to control body temperature 

d) opened up fashion industry and new ability to buy clothes

The correct answer is C.

It is thought that millions of years ago, our ancestors were very hairy - as hairy as chimpanzees and gorillas.

It is thought that losing hair on the body allowed an incredible new advantage. We could acquire the ability to sweat and better control our body temperature!

In fact, sweat glands seemed to evolve in parallel with loss of hair. By being able to sweat, humans could thermoregulate like never before.

Humans could then travel long distances across hot regions and find food. We could run  and walk without the same degree of worry about overheating.  

Even minor increases in body temperature can lead to heat stroke so this is a serious issue for all mammals.

Imagine yourself wearing a thick winter coat in the middle of summer. (imagine some kind of Canadian made coat suitable for Arctic exploration). It’s an awful feeling to have to wear that coat in summer. You want nothing more than to take the coat off and if you are not take the coat off then you’ll be looking for shade, a cool beverage or a pool to dive into (or all three).

Our ancestors with thick hair on the body were certainly not likely to go anywhere far in the heat. They needed a source of water close by. In short, they were limited.

Losing hair and gaining sweat glands opened up a new world of possibilities for our ancestors. 

Were it not for hair loss experienced by our common ancestors, none of us would be reading this post!