While shampooing my hair this morning, I got to thinking about hair. Specifically, why humans still have hair.
Originally I would imagine that the evolutionary gears “encouraged” hair traits over the entire body for combating colder climates. You can see this in pretty much any woodland mammal if you page through your A-Z kids picture book on zoos.
But humans are an interesting bunch, because we don’t just live with what environments we find—we shape our environments to suit what we want. Case in point: heating & air conditioning systems, hats, gloves, and coats.
With all of these post-genetic adaptations to the variance in thermal surroundings, humans don’t really need hair for its original “purpose”. I have this theory that perhaps this is why we really don’t have full-coats of thick body hair anymore. If you think about what purpose the remaining little bits of hair provide, they are secondary. Firstly in areas of skin-skin contact hair seems to act as a mediator for an air-cushion allowing trapped water-based liquids to evaporate freely and also allowing both patches of skin to freely move without sticking (hair reduces friction). Secondly, those sparsely distributed hairs on your extremedies seem to act as good vectoral indicators of gaseous fluid flow across the skin surface.
But neither of these two things is entanged with our survival anymore. Hair isn’t important in the natural-selection algorithm for us anymore. Because of our self-interaction and post-evolutionary adaptation it would seem that a lot of the quirky traits that we developed to keep us alive on this planet have become less-useful since we started setting our thermostats to 76°F, buying humidifiers, and locking our doors at night.
So my question is, how long will it take before random mutations and sexual reproduction start to take our non-useful traits on an evolutionary random walk? I think you can see this happening by looking at things like baldness.
I’d like to point out that I didn’t really research any of the biology around what I wrote, so I may be completely off-the-mark on some of it.
I think the part you’re leaving out is sexual selection, a completely different process than natural selection. As long as most human cultures continue to believe that hair is sexy, we’ll continue to have hair. In fact, if baldness is a hurdle to reproduction (which, in some shallow circles, it is), then hair is actually a sexual advantage, and it seems like ealry baldness should eventually filter out.
But then, I’m no biologist either.
I beg to differ. After experiencing life without hair, I can assert with confidence that eyebrows and eyelashes do serve a purpose: to keep crud out of your eyes. Try cooking something smoky or deep-fried, like chicken wings, and tell me you don’t need hair protecting your eyes. Think about it- How many times have you or someone you know joked that wow, that was quite a fire, it singed my eyebrows off! Also, in colder climates the hair really keeps in some extra body heat.
I am a quasi-biologist, but didn’t research anything.
So to summarize the above: Hair is sexy, lowers friction, keeps you warm, and makes cooking safer. ;+)