The Hairless Ape

Humans have very little body hair compared to most other primates.  There are several theories on this, summarized well and interestingly at http://www.nytimes.com/2003/08/19/science/19HAIR.html, which makes for a very interesting read. The currently accepted theory is that it’s an adaptation that helped avoid diseases spread by lice and ticks which found hiding places in fur.

This immediately raises the question: why didn’t other animals lose their fur for the same reason? That looks like an easy question to answer. Lice and ticks are not the only factor.  For example, in cold climates man could survive by wearing the fur of animals he killed.  Animals couldn’t do any such thing, so having a fur pelt was much more important than getting rid of lice.  This sounds like a plausible explanation, but it is wrong. The article says that man lost his body hair about 1.2 million years ago (estimated assuming the tick theory holds), but only started wearing clothes about 50,000 years ago — so there was a period of several hundred thousand years when man was hairless and naked. Other animals (at least those living in the same regions as man) could have lost their fur during this time, but didn’t.  I don’t have a good explanation.

All this changes if we consider a different theory for the loss of body hair.  There are many we could consider, but one of the more fanciful theories is that of the Aquatic Ape, which contends that, sometime in our remote past when all humans were still living in Africa, all the ancestors of currently extant humans were trapped in a small region around a shallow sea.  According to the theory it’s possible there were other humans not trapped this way, but they all died out.  Eons later, another cataclysm scattered these humans, who had now developed adaptations like the loss of fur to be able to swim better, as well as a slight webbing between their fingers, and a host of other adaptations.  To me this sounds more like science fiction than fact, and it has little acceptance in the scientific community.  But it’s a fun theory.