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One of the questions still unsettled in human evolution is that of why humans are "naked" - that is, why don't we have a coat of fur like most mammals. This was one of the questions Desmond Morris wrestled with in his popular book "The Naked Ape". The answer he provides in the book, that mankind was for a brief time aquatic, has not panned out and never gained currency. There are several good hypotheses for this nakedness question, and in this essay I will discuss them, advocating my pet theory over the one which has most currency these days. The dominant hypothesis seems to be that sometime during the period of time when man's ancestors were roaming about the savanna (say 2-3 mya), they developed the ability to sweat to better regulate their temperature on the hot plains. Along with this was a general reduction in the amount of fur so as to reduce the overall body temperature. One problem with this theory is that very few other mammals on the African plains are naked. In fact, nakedness in mammals is a fairly rare affair. Even if it is a light coat, fur is handy thing to have, especially on those occasions when it gets a little cool out. Our ancestors learned, around the time they shifted to become hunters, that a coat of fur was handy to have, to keep warm. Even animals with one coat don't mind an extra, although very few have the means to add an additional one. Man, with his discovery of tools and his utilization of the bones and flesh of the animals he killed, did have the means. He invented clothes. Now one of the main drawbacks of having a coat of fur is parasites. Lice, fleas, and other insects find fur coats lovely homes. They're warm, provide sustenance, and generally provide shelter from predators. On the other hand, the host animal finds these parasites annoying. And in some cases deadly. Carrying deadly plagues, parasites can decimate a population of otherwise healthy individuals. Animals with fur having various grooming habits which reduce the impact of parasites. On the other hand, when you've got two coats, one permanently attached and one you can take off, you have a double threat from parasites. Losing the permanently attached coat may have been a method of reducing the mortality associated with parasitic plagues. Especially when you can still stay warm with your other coat. It is my contention that various forms of clothing have been around long enough to have an impact on the distribution of various hair on the body, as well. First, the distribution of hair seems to vary with the various tribes of people on the Earth. Second, hair seems to less in certain areas often associated with basic clothing (e.g. hair on the legs generally stops where short pants would start). Understand that this is a secondary effect, with the primary pressure for nakedness being a response to clothes bound parasites. Perhaps this whole discussion is a bit academic, as the loss of fur seems to have taken place sufficiently long ago that it will be quite hard to find any record of when exactly it occurred. If one were able to clone various human ancestors from (currently non-existent) DNA, one could judge when it took place. Alternately advanced study of DNA from humans and chimps might show the genes which regulate or influence sweat and hair patterns, and somehow argue for when these genes appeared. The debate over human's lack of fur (or the sparseness thereof) centers on the environmental pressures that might drive the nakedness to be favored over retaining fur. And generally the advantage of fur is regulation of body temperature. The advocates of a hot savanna-driven nakedness point argue for the radiator aspects of not having fur. The advocates of a clothing-based, parasite & disease driven nakedness argue for the sanitary aspects of not having fur. One of these days I need to dig up some relevant data on all this. |