Evolutionary Human Hair Loss was Handy for Running Around

In modern times we naturally start to worry if we notice that we are losing our hair. But for early man living hundreds of thousands of years ago, widespread hair loss was a matter of survival for the species.

Now, a new scientific study published in the journal Proceedings of the National Academy of Sciences has proposed a new answer to the question of why we lost the majority of our body hair.

The study’s authors, Graeme Ruxton of Glasgow University and David Wilkinson from Liverpool John Moore’s University, say that their computer models suggest that early man lost his hair as a direct result of walking, and running, on two feet.

In order to put this new research properly in context it’s necessary to look at how man originated and has evolved to his current state as a bipedal and relatively hairless ape.

Man’s journey from hairy swinger to naked ape

Established theories tell us that all primates (the evolutionary order of which we, other apes and monkeys are a part), share a common ancestor that lived around 40- 50 million years ago. Through genetic mutation and the natural selection of favourable characteristics, new species formed and branched off along their own evolutionary routes.

One of these branches is known as the Great Apes, and includes chimpanzees, gorillas, orang-utans, and of course humans. What this means is that at one point our direct ancestors were walking around on all fours and covered in hair just like the rest of our ape cousins.

But for some reason, in the six million years since we split off from the species closest to us, the chimpanzees and gorillas, our ancestors gained an evolutionary advantage by standing on two feet, which allowed them to survive and breed more effectively. At roughly the same time we began to lose our hair. Effectively, the conditions were such that individuals with less hair were more likely to prosper, and so pass on the ‘less-hair’ gene to their offspring.

Various theories have been proposed to suggest why losing our hair in this way was beneficial, and why we began to walk and run on two feet instead of four. Previously it has been suggested that we lost our hair to enable us to swim more effectively.

Losing hair made it easier to go about our day

This most recent theory, which is based on the analysis of computer models, suggests that humans as a species gradually lost their hair because it allowed them to be more active on two feet during the day. For example, it allowed them to run after prey during the day without becoming overheated and exhausted.

The scientists say that, “Progressive hair loss [was] selected and this allowed individuals to be active in hot, open environments initially around dusk and dawn without overheating. Then as our ancestors’ hair loss increased and sweating ability improved over evolutionary time, the fraction of the day when they could remain active in such environments extended.”

So, the research suggests that the reason why we have far less hair than other primates is because it fitted in with our new two-legged lifestyle.

Furthermore, having less hair has had a great range of effects on the behaviour and further evolution of our species, as we have been able carry out intensive physical activities throughout the day rather than just in early morning or evenings.

At this point you might well ask, “Well why do we still have hair on our heads?” In truth, we can’t know for sure, but there are a variety of popular theories, such as that it helps protect the tops of our heads from harmful UV rays from the sun.

As with many scientific theories about things that happened millions of years ago, there is a fair amount of educated guesswork involved. One thing we can be sure of though is that for some reason it was advantageous for the human species to lose the majority of its body hair, yet retain a thick layer of hair from the scalp.

What about my hair loss?

As for why both men and women often lose their hair as they get older, this is due to the action of an enzyme in the body which turns the hormone testosterone into the more powerful dihydrotestosterone (DHT). This DHT causes follicles to gradually shrink so that they cannot be seen with the naked eye, leading to the appearance of hair loss. This process is known as Male Pattern Baldness in men and Female Pattern Hair Loss in women, and is a genetically inherited condition which roughly half of all people are predisposed to.

Only time will tell if there is any evolutionary advantage to going bald, but if you’d rather not wait to find out, contact us at The Belgravia Centre to find out how you can stabilise hair loss and re-grow your hair.

Interesting articles