The Hairy Tale of the Naked Ape

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!

A Hairy Issue for Humans

The amount of your hair from the neck up is different from your hair (what little there is of it) from the neck down. There are sexual differences with respect to hair between the human male and female as well both from the neck up and from the neck down. The curious part is that neither neck up or neck down or sexual differences tend to have close parallels with nearly all the rest of the terrestrial mammalian kingdom, mammals we presumably naturally evolved from. The 64 cent question is why?

Humans vs. Mammals: Humans tend to have way less body covering usually termed hair and/or fur relative to other mammals, our size or below, including our primate ancestors. That our first uniqueness. Why is that? Now apparently our lack of fur, why we lost the fur we presumably once had way back once upon a very remote time ago, was because we developed sweat glands to regulate heat, which, IMHO was a retrograde development.

Fur is a good regulator whether retaining or allowing body heat to escape. Some animals, like cats, shed some fur as the warmer weather approaches, though it thickens again as winter approaches. Sweat glands are only a cooling mechanism. That’s okay. But be that as it may, the ‘why’ question now becomes one of explaining why humans alone out of all our primate cousins developed sweat glands thus contributing to the evolutionary loss of our fur. You’d think what’s good for the human is also good for the gorilla, chimpanzee, gibbon, orang-utan, etc. So, why were humans and humans alone selected to be ‘the naked ape’? Was it a normal natural selection, an evolutionary fluke or by design?

Neck Up / Neck Down – Distribution: For the human species, there’s an obvious dichotomy between the amounts of hair we have from the neck up relative to the neck down. But any breed of cat, or dog say will tend to be just as furry neck up as neck down. Why do we have a neck up / neck down division to our relative hairiness? Was it normal natural selection, an evolutionary fluke or by design?

Neck Up / Neck Down - Haircuts: From the neck up, humans tend to need to have the occasional trim or haircut, or shave. But, humans, like the rest of the mammals, don’t need haircuts from the neck down. To b honest, the rest of the mammals don’t need haircuts from the neck up either, unlike humans. Why is that? Why do humans need haircuts? Was it normal natural selection, an evolutionary fluke or by design?

Sexual Differentiation: Hairiness or furriness has no obvious sexual differentiation in nearly all the rest of the mammals. You can’t normally tell the sex of a mammal by the amount of fur it has. Male cats of any particular breed will have as much hair on their bodies as their female counterparts, although male lions have manes that lionesses don’t have. Still, lions and lionesses apart, that sexual distinction is part and parcel of the human species. In humans, males tend to be way more the hairier in terms of overall body covering. Males also tend to have far more hair on the front of the face – beards and moustaches. But that’s not always true on top. When it comes to hairiness, there’s not only a neck up / neck down division but a differential between the sexes. Why is that so? Was it normal natural selection, an evolutionary fluke or by design?

Natural Pattern Baldness: I need start here by making a distinction between thinning hair which a goodly percentage of human males and females experience as they age, and baldness. Some human males, percentages increasing with ever increasing age, tend to lose, for reasons apart from disease, stress, chemotherapy, etc., more of their hair up top – the common occurrence called male pattern baldness or partial baldness or massive thinning of the hair on top. But whether to a greater or lesser degree, there’s not an inevitability of hair thinning and total loss of hair up top with age in human males. That alone suggests that aging isn’t the be-all-and-end-all of the condition.

Human females, though to a far lesser extent, will also tend to exhibit hair thinning (as opposed to total baldness), again, percentages going up as one’s age goes up and up. On balance however, you see far, far fewer females than males with bald spots relative to gradual hair thinning.  

It’s an unfortunate fact of life that I’ve got a lot less hair up top today than I had in my teens. That applied to my father and equally as well to my father’s father. The question is why is baldness an unfortunate fact of life for some since baldness isn’t a fact of life for all human males; it certainly isn’t as much of an issue for the female of the species (another of those sexual differentiations noted above). Baldness certainly isn’t a fact of life for most hairy or furry species (another human vs. animal data point to be added to the above), like our companion animals, be they cats or dogs, mice or rats, rabbits or guinea pigs, ferrets or alpacas. However, the thinning of the hair isn’t quite uniquely confined to humans. Some primates, but only a relatively few species, show some progressive thinning of their scalp hair following their version of puberty.

So baldness tends to be fairly obviously a sex-linked genetically transmitted condition that arose as the result of some genetic mutation in an ancestral primate and/or human male multi-thousands upon thousands of years ago, way before the start of written history. But lots of questions arise. Why balding on just the top of the head; why not, especially with inevitable aging, the entire head (and face)? Why not the entire body’s covering of hair? Humans have so little fur that the thinning and loss of the rest of it shouldn’t matter really. [There are medical conditions that do involve total facial, even in extreme cases total body hair loss, but they aren’t related to normal hair thinning and baldness.]

If hair thinning and eventually baldness (in some individuals) confers no evolutionary advantage or disadvantage why is there nothing similar in any other non-primate mammalian species? Actually there might be an evolutionary advantage in that genetically linked hair thinning and eventual baldness presumably started with one mutation in a statistical sample of just one individual (perhaps even one of our ancestral primate cousins) which has now spread to include a reasonable minority of adult males (or majority of adult males, even females if you count just hair thinning and those over 60 or so). However, why did that original mutation spread as it obviously did? What could that evolutionary advantage actually be? And if there is an evolutionary advantage, why isn’t the condition more widespread throughout mammalian species? For the moment, those questions stump me. Was it normal natural selection, an evolutionary fluke or by design?

Spots / Stripes / Plain: Humans, from the neck up, have a single natural hair colour. Human hair tends to be blonde, red, brown or black (I’ll ignore grey/white since that’s an aging issue). So here we have one species, four different hair colourations. Mammals of any one species tend to be one of two colour patterns, neither of which has a parallel akin to the human condition. Either all members of a species are just one plain colour and only that colour; polar bears are white; brown bears are brown (the very rare condition of acquiring the genetic mutation and ending up an albino is a separate issue), or else all members are multi-coloured with spots, stripes; often an irregular pattern. All humans, one species, aren’t all the same with respect to hair colour like brown bears – some humans are blonde, or black or red-haired. Now I’m aware that there are black cats and white cats and grey cats too; my next door neighbour has two dogs of the same breed, one cream and one black. Then there’s the normal grey mouse and the (laboratory) white mouse. But cats and dogs and similar mammalian companion animals have been bred or ‘created’ by humans via artificial selection criteria. While the grey mouse is probably natural, the white mouse again has been ‘created’ for laboratory use. Tigers have stripes; leopards have spots; calico cats tend to be multi-coloured with an irregular symmetry. Humans have neither stripes, spots nor an irregular colouration pattern. Why are humans different from other mammals when it comes to the general rule of one species – one hair colour, or one species - multi-coloured fur patterns? Was it normal natural selection, an evolutionary fluke or by design?

But the biggest anomaly of all is what natural environmental changes – triggers – survival-of-the-fittest scenarios transpired that could account for all these differences between the human mammal and the rest of the mammals blessed with fur? It’s not an advantage one would think to need a haircut; the amount of relative hairiness between males and females, including baldness, is great enough to require an explanation, but I can’t think of one; and there would appear to be no advantage in humans coming in four basic hair colours, yet no combinations of those. It is all very strange.

Summary: Non-human mammals our size or less are way more covered in hair or fur than humans. Non-human mammals show no sexual differentiation in their hairiness or furriness. Nearly all non-human mammals show no neck up/neck down differentiation with respect to hair covering. Non-human mammals don’t need haircuts. Non-human mammals don’t go bald though some primates exhibit hair thinning. So what’s up with humans? Were all these anomalies just normal natural selection, an evolutionary fluke or by design? And if by design; whose design? And what was their ultimate purpose? It’s a hairy issue!