Tuesday, June 30, 2015

Hair and blood-sucking insects

Hats off to Melissa for her post at Gizmodo.com called "Why don't humans have as much hair as other primates?" I couldn't have (and won't) say it better.

Instead, I'll summarize her write-up in bullet points:

  • Debunked theories as to why humans have less hair are a.) the "aquatic ape theory" that posited we lost it in order to swim better during our aquatic phase of evolution, and b.) we lost it in the early days on the African savanna to allow our body sweat to more easily cool us off. To find out how these theories have been disproved, click here to read the Gizmodo post.
  • A third theory is more likely -- that our hairless bodies are less attractive to lice, ticks, and fleas, helping us itch less and also preventing the spread of disease.
  • Or a fourth, that humans have an exceptionally long childhood, so our hairlessness is simply prolonged prepubescence. (Actually, we aren't hairless, of course. Our body hair is just really fine.)
  • Most intriguingly, recent research suggests that we humans signal one another via our bare skin. Here's a quote from a 2013 article in USA Today called "Why Aren't People More Hairy?
"After all, the pattern of hair density in humans results in a unique (within primates) visual presentation," says King, the author of How Animals Grieve. "As other anthropologists have noted, we humans possess a whole 'skin canvas', a place of vibrant self-expression, that may well have played a significant role in our behavioral evolution."
It's very cool, the idea that humans lack hair the better to read one another's rages, blushes and bruises. But reflecting on the misery of those blood-sucking insect bites, I weigh in heavily for theory number three.