Why are We the Only Hairless Ones?

While men are agonizing about going bald, scientists are wondering why humans are so hairless. Our close cousins the chimps have no hair loss problems. Researchers think we humans may have lost our body hair so we’d have fewer parasites.

Nakedness is extremely rare among mammals. Other naked mammals are elephants, walruses, pigs, whales and mole rats. Scientists used to think we lost our hair in order to control our body temperature, since we evolved in Africa, where it’s hot. “The body cooling hypothesis is interesting, but some of the advantages in not having fur in the sun become disadvantages at night,” says evolutionary biologist Mark Pagel. “In animals, ectoparasites like biting flies, exert tremendous fitness costs?they really affect our health. Our view is that hairlessness is an adaptation for reducing the ectoparasite load.”

So why didn’t apes lose their hair too? Pagel reminds us that we’re the only ones who did other things as well, like learning how to make fires, shelters and clothes. Chimps spend a lot of time picking bugs out of each other’s hair. If we’d spent that much time on grooming, we wouldn’t have had time for all those achievements. And once we had fires, shelter and clothes, we didn’t need a lot of hair anymore. “It’s one of those nice cases of gene/culture co-evolution,” says Pagel. “It’s the culture which helped us acquire the means to lose our hair.”

Most ETs are described as hairless, so maybe bald men are the wave of the future. Ever wish you could achieve contact? Lisette Larkins tells you how she does it on next week’s Dreamland.

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