Zoologist/Anthropologist Desmond Morris authored his best selling book “The Naked Ape”, which was all about us humans, in 1967. We’re the naked ape. According to Wikipedia, “The book was so named because out of 193 species of monkeys and apes only man is not covered in hair.” The 64-cent question is why we are naked (as opposed to being a nudist), as in why don’t we too have a natural fur coat? Extreme exceptions to the rule require explanation(s). I wish I had one for something’s screwy somewhere!
Fur, like feathers, is a very good temperature regulator. In cold weather it traps your body heat next to your body; in hot weather it can loosen or fluff up a bit and allow your body heat to escape into the environment. Further, fur (or a considerable hairy covering) is excellent protection from ultraviolet (UV) radiation. UV rays as we know can cause tanning, a painful sunburn, and ultimately skin cancers. On balance, fur has a positive evolutionary survival value as witnessed by the large number of mammals that have a natural fur coat.
While not all species of mammals wear a natural fur coat, our primate ancestors, past and present, did and do. Since humans are their naturally evolved descendents, it would be logical to expect Homo sapiens to also have a natural fur coat. We don’t. Where’s our fur coat gone?
Any ‘Age of Mammals’ or physical anthropology text will show our hominoid ancestors (like Australopithecus from roughly 3.2 million years ago) as being quite the hairy critters we once were, even while we were well on the evolutionary road to the modern human of today. Somewhere between then and now we lost our fur, but our primate relations (those 193 species of chimps, gorillas, monkeys, etc.) didn’t – yet we shared the same environment way down Africa way with many of those furry primates. Why one (us humans) and not the many (them primates) lost and retained respectfully their hairiness is mystery number one.
It makes relatively little sense for humans to have lost their fun covering, migrate to cooler climates, then have to invent clothing when the original fur covering would have adequately served the same purpose. That’s mystery number two. Having to invent clothing carries with it a whole host of other required skills and technologies that would have needed to have been discovered and learned and passed on generation to generation like skinning, and curing, and sewing, making threads, the concept of buttons, and belts and ability to tie knots – all unnecessary if we had just kept our fur. There are primate cousins of ours that survive and thrive in colder, even snowy climates with just the benefit of fur.
Now one reason we lost our hairiness might be that we evolved sweat glands to rid us of unwanted heat. However, sweating in hot, humid weather would make for soggy fur, so by-by fur. Yet fur is a good heat regular. So why, if sweat glands are so superior, didn’t other primates evolve sweat glands? [Actually, like cats and dogs, primates can sort of ‘sweat’ and lose heat through the non-hairy parts of their body, like the pads on their feet/hands, their naked noses or via panting.]
So why did we trade our ancestral fur coat for sweat glands, which, by the way, is only a cooling mechanism and not overly efficient in humid conditions (“it’s not the heat, it’s the humidity”), and further force the need to invent the totally unnatural concept of clothing which no other animal species makes any use of?
A New York Times (19 Aug 2003) article made the suggestion that it was an advantage to lose fur because it rid humans of the parasites that inhabit fur. However, all furry critters have parasites. Cats can have ticks and fleas. So why aren’t my cats naked? In other words what’s so damn unique about humans with parasites that we lose our fur, yet other furry animals with parasites didn’t – lose fur that is?
Another possible reason we lost our fur is that we’re large. Larger animals have greater difficulty in getting rid of excess body heat relative to smaller animals. As one grows larger, body volume (which generates heat) increases faster than body surface area, from which heat escapes. Perhaps that’s why really large animals like cattle and horses and elephants are way less hairy than cats and rats and mice.
However, while humans are large relative to many primates, some primates are roughly our size, and furry, so that’s not the be all and end all of explanations. We should be roughly the right size to be covered in fur as many other mammals roughly our size, even larger (like bears or lions) are fur covered.
Of course even very large mammals living in extremely cold climates still require fur, like your Ice Age woolly mammoths. Speaking of the Ice Ages, they should have provided an evolutionary incentive for us to reacquire our furry cover – but strangely we didn’t. Which reminds me; fur is a good insulator and protector against snow - Snow on fur – no big deal; Snow on skin – well talk about chilling out. And fur also offers some protection against the wind-chill factor. Cold is one thing; cold when the wind is blowing really feels extra cold and can rob you of body heat quick-smart.
Speaking of larger hairy animals, specifically potential primates, there’s the often reported (never proved) Sasquatch, Big Foot, Yeti, Yowie, (and a host of other cryptozoological bipedal hominoids reported from around the modern world). If these beasties really do exist, and a lot of people, even scientists give that more than just some credibility, the most likely candidate is the now not so extinct giant hominoid ape Gigantopithecus (traditionally considered to exist only from 1 million to 300,000 years ago). One characteristic of the modern sightings, from anywhere in the world, is an ape-like being covered in a lot of fur. So, Sasquatch (if it exists) matches us in being bipedal, but kept its fur. We’re still the odd one out.
Of course you might argue that we haven’t lost all our heavy covering of fur – we have a head full of hair (or at least most of us have). Maybe our hair is to keep the brain warm, but it’s not much comfort in having a warm brain when the rest of your body is experiencing hyperthermia. In any event, there appears to be a critical difference between our head (and facial) hair and real fur. The difference is that we need hair cuts because our hair growth doesn’t know when to quit growing! We’ve all seen women with hair lengths down to their waist; men with beards a bird could build a nest in. If that sort of uncontrolled hair growth happened in the natural world, it might look, but ultimately wouldn’t be, comical. Extrapolate a woman’s waist length hair to your pet cat or dog and your pet (or any equivalent wild animal) couldn’t function. I mean we’ve all heard shaggy dog stories, but not that shaggy!
Of course there are other means of temperature regulation apart from fur. One can warm up in the sunshine; cool off in the shade regardless of having skin or fur, but at night it’s all shade, and if it’s already cold and you’re naked in your skin, there’s not much temperature regulation you can do, except shiver.
Quite apart from the heat regulation issue, fur colourations and patterns are useful as camouflage. Some mammals even change their fur colour with the seasons – for example a white fur coat in the snowy winter. Soldiers on the other hand have to wear ready-mades, having lost all natural furry camouflage they may have once had.
In conclusion, the question is, did we lose our fur because we evolved sweat glands, or did we have to evolve sweat glands because we lost our fur, fur which again seems to provide a perfectly good means of heat regulation as we note in our cats and dogs and many other mammals? Translated, there was no real environmental reason to lose our fur unless we evolved sweat glands, but then it’s back to the question why our kissing primate cousins didn’t evolve sweat glands if they provide a more efficient means of losing heat – which they don’t (recall humidity). And that provides no explanation for retaining heat; an ability we lost without fur and requiring the invention of the garment industry as a replacement.
I don’t know the answer to why we lost our fur; it certainly is a biological anomaly of the first order. However, I need to stress the word “ape” in that ‘naked ape’ phrase of Desmond Morris least anyone attribute this puzzlement solvable by saying it’s all due to man (and woman) being created in God’s image. That’s only attributable should ‘God’ be a flesh-and-blood extraterrestrial IMHO. To be consistent with my point of view that humans were created in ET’s image via genetic engineering and artificial selection, well, maybe ET wanted a naked ape as a subject and not a walking, talking hairy carpet!
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