Hair: Curls cool the head

The result: a wet scalp always gives off heat, especially when running and hairless. The three wigs couldn’t completely prevent this, but it did greatly reduce heat loss. When the head was dry, it was different: now there was a greater risk of overheating, especially when the head was bald. All three wigs protected against this, but to a different degree: the best protection from the sun was provided by thick curls – under their armor, the artificial scalp either barely heated up, or even gave off heat when there was a strong draft.

Thick curls form a thick shield

The fact that head hair not only kept early humans warm, but also protected them from the sun’s rays isn’t a new idea: an already ancient study proved that bald heads sweat at least twice as much as hairy ones. But after their experiments, the researchers believe that the thicker braids in particular helped them survive longer periods without water—especially at the point estimated 2 million years ago when the brain began to develop.

In this study, wigs were provided to dark hair continuously. Lasisi and her team explain that with short hair, lighter color protects better from the sun, but not with long hair. Then it is necessary that the hairs form the thickest shield possible. It is still not clear at what stage of human evolution hair began to curl. The Group considers it conceivable that this development began in Australopithecus I started. Whether curls can also be an advantage in colder climates remains to be investigated.