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The Peon

Why are we naked?

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I have been looking for weeks for a good answer to this question, and have yet to find one that makes total sense. Why are humans the only primate to lose its hair?

 

One of the best explanations that I read to date said that when humans were almost extinct we resorted to being fishermen, and as aquatic apes it was more beneficial to lose the hair in favor of sweat glands. Another good explanation was sexual selection.. less hair meant more skin contact which heightened sexual pleasure, and as emerging intelligent thinkers and sex machines, it was sexually selected into us. Would love to know what others think.

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God made us that way.

 

However, the natural selection theory while sexual attraction could have influenced next generation humans into which they had less and less hair. Which is a possibility. What you have to question though is if humans originally had a lot of hair. Maybe we didn't.

 

There are some animals without a lot of hair. Naked mole rat.

You could look at the wolf boys which in my idea somewhat shows a very primitive and ancestral trait which many scientists may disagree with me about.

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God made us that way.

 

However' date=' the natural selection theory while sexual attraction could have influenced next generation humans into which they had less and less hair. Which is a possibility. What you have to question though is if humans originally had a lot of hair. Maybe we didn't.

 

There are some animals without a lot of hair. Naked mole rat.

You could look at the wolf boys which in my idea somewhat shows a very primitive and ancestral trait which many scientists may disagree with me about.[/quote']

 

But we supposidly shared a common ancestor with primates, and they all have hair. So somewhere along the line, either 192 species of primates evolved hair from being hairless, or we became hairless from being hairy.

 

As for the wolfboy, we actually develope a thin coat of hair when we are in the womb, and oddly shed it right before birth. Some babys actually are born with this coat, much to the terror of the mother, while others never lose it, and thats the wolfboy.

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IIRC, it has to do with thermal insulation. Fur is, basically, an insulator, and for quadrupeds, it can insulate against the sun beating down on their backs. When humans stood upright, however, less of their body was exposed to the sun, and the parts that weren't (most of the body) could actually benefit from losing the hair, which would allow evaporative cooling to occur thanks to sweat.

 

Mokele

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.. it was more beneficial to lose the hair in favor of sweat glands...

 

 

I think we have people here (like Mokele and Skye) who probably know what the mainstream explanations are for this, so what we can do is play a guessing game. I will try to guess. your post is suggesting one or two guesses. We will see how close we are to the accepted mainstream ideas.

 

I think that losing hair in favor of sweat glands is a good idea but I do not think it had to do with fishing.

 

I conjecture that it had to do with LOSING HEAT and evolving a BIG BRAIN that uses around 100 watts of power just maintaining itself.

 

If you are some forlorn scavenger on a hot African grassland who has to roam around for miles and occasionally run like hell you could die from overheating if you were forced to wear a fur coat!

 

In thermodynamics physics the efficiency of engines (including metabolism and muscle engines) goes way down if they cant get rid of waste heat easily.

 

So out on the African boonies your life may depend on being able to sweat and have any little breeze cool your skin.

 

The reason other wide-ranging scavenging animals in hot countries dont lose their hair is because they dont have big brains with a heavy nonstop energy consumption. The hominid enlarged brain is a PHENOMENAL calories guzzler and generates a lot of waste heat. for many people, waste heat is pretty much all their brains generate present company excluded.

 

it is maybe not running 100 watts but on the order of that, and when you stop to rest and cool off it still keeps running that.

 

biology buffs please correct me if I am wrong

 

OOPS I SEE NOW MOKELE ALREADY ANSWERED! well I put my guess before I saw his post.

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Wow that rocks. I can fully understand the heat difference between a bipedal homonid in the african sun, compared to a quadripedal anything. So in effect, standing up caused alot of #($% to go haywire. :eek:

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Why do we have hair in our armpits then? (not trying to poke holes in this) i mean if what your saying is true then souldn't wea have also lost our armpit hair since it is almost continually in the shade?

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Well in my view. We either came from hairy apes, or we weren't hairy.

 

But since of things like armpit hair, i consider the idea of once being hairy.

If back in the day we were seriously hairy, and e/devolved into less hairy beings through natural selection and some understanding of physical attributes in our environment, then people would do their best to mate with others with very little hair.

 

In that sense, eventually those with less hair could sense things around them and perhaps someone blocking air path so they were aware of enemies around them.

 

Also, about the armpit thing. Perhaps we haven't completely rid ourselves of all hair and that is why we still have hair in some places.

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IIRC, and this definitely isn't my field (monkeys are just python food to me), the pattern of hair we have is neotenic, and we lost our hair via neoteny, which is the process by which juvenile traits are retained into adulthood. This process also accounts for numerous other aspects of our physiology. In many respects, we look an awful lot like an embryonic chimp.

 

Mokele

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Embryonic as in the idea that we are naked as an embryonic chimp is? Which seems like an interesting transitional effect if we in are earlier stages are compiled with a thin layer of hair.

 

It's as if we are opposite with vocal cords, a more advanced cerebro, and... very little hair. However on the down side, we don't have the strength as Grape Ape.

 

grape ape grape ape ^_^

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Embryonic as in the idea that we are naked as an embryonic chimp is? Which seems like an interesting transitional effect if we in are earlier stages are compiled with a thin layer of hair.

 

It's as if we are opposite with vocal cords' date=' a more advanced cerebro, and... very little hair. However on the down side, we don't have the strength as Grape Ape.

 

grape ape grape ape ^_^[/quote']

 

We actually have alot of hair, its just very fine and small compared to other primates.

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it might be an idea to do some research on the Aquatic-Ape, many of the args presented as quite compelling!

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it might be an idea to do some research on the Aquatic-Ape, many of the args presented as quite compelling!

 

On the surface, perhaps, but they don't stand up to scrutiny. Here is a critique.

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elephants dont have much hair

 

but they walk on four legs and have broad backs exposed to sun

 

Mokele gave the theory that when apes stood up and walked on two legs they didnt need protection from sun, that hair gives, like for example on a broad level back area.

 

my guess is still the HEAT THEORY which is that you lose hair when you have a problem dumping or getting rid of surplus heat

 

the reason the elephant has a problem is because she is big

so there is this reduced AREA/VOLUME ratio

big things hold in heat better because they have less surface area

 

the elephant makes waste heat depending on her volume, because all her cells have to metabolize, so she makes a lot of waste heat but does not have good ways to get rid of it. Big ears do probably help as a place to cool the blood by radiation and convection. But also HAIRLESSNESS or having very little wimpy hairs instead of fur, that would help.

 

So I am conjecturing that people lost their hair (by adaptive neoteny suggested by Mokele) under similar evolutionary pressure

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Meh, I thought I was reading proof

 

Whoa, slow down there fella, I didn`t present it as a "Proof" or a "Theory" etc...

simply that it might be an "IDEA" to read something about it.

it presents interesting args, some of which are factual, some are disproven, some have no evidence at all eitherway. But for a well rounded research, it`s important to look at ALL reasonable args, and then try and glean Some sort of verifiable truth from them.

 

you should keep reading that site! and then you should read the site that Swansont gave you too, between them you WILL learn something :)

 

and that`s what it`s ALL about isn`t it?

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I think most of the issues have already been covered, but I'll put in the way I understand it. Western Africa, where man's ape-like ancestor came from is very moist and there is a dense cover of trees that provides constant shade. Under the cover of the trees our smaller ancestors were able to keep cool. Our hair acted like an insulator that kept us warm during the occasional chilly night and cool when it got a little warm.

 

Now, as man's environment changed from a lush jungle to a dry savanna man needed to adapt or perish. To find food he needed to make increasingly more trips out of the trees to scavenge food or get a drink of water from a water source. This meant speed was a necessity because there were dangerous predators like large cats. So being able to run faster became a priority. We needed our hands because we already made use of very primitive tools and we still needed to climb the trees for protection. Plus we already had a semi-upright flexible body type from our ancestors.

 

So there we are, an ape-like creature that has become somewhat more upright to run faster on two legs and with a somewhat larger body size to accommodate longer more muscular legs so we can awkwardly run out of the trees into the savanna to gather resources. The problem with the larger body size is that the larger you become the easier it is to hold onto body heat but the harder it becomes to get rid of the body heat. In addition, we are running, which uses way more energy and heats up our core body temperature quickly. Not only are we running, we are running out under the hot African sun. In order to maintain longer periods of running without overheating we needed a more efficient cooling system.

 

The mechanism of sweating didn't use to be all that useful in the wet forest because there wasn't much of an air flow in the jungle, it wasn't as hot, and most importantly, it was very moist. Because it was so moist in the jungle sweating wouldn't have done much to cool us off because when there is already so much moisture in the air there isn't much in the way of evaporation. But now we are in the savanna where it is much dryer and the direct sunlight makes it much hotter so a sweat-based cooling system becomes the greatest thing in the world.

 

But what about our hair? It use to be great as an insulation system when we only experienced a certain amount temperature change but now the most important thing is being able to avoid hyperthermia when we are running our ass off from a hungry cat. The problem with hair is that it acts like an insulator by creating a pocket of air around the body that is insulated from the environmental air's temperature and convection currents. Plus in is keeping all of our already over heating body heat next to our body when we really need to get rid of it. Most importatnly it is interfering with our newly developing sweat-based cooling sytem that needs the exposure of the convections of air currents to constatly take away heat through the process of evaporation. So those among us that have alleles that cause us to produce thiner, more sparse body hair are able to cool down more efficiently and they are able to get away from the preditors and possibly chase down a poor creature or two without overheating, so they are surviving and they are able to pass down their genes. Those who have thicker coats are overheating and perishing before they can procreate.

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So basically my opinion is that hair insulates the body from exposure to the outside air's convection currents and reduces the amount of evaporation that is needed for a sweat-based cooling system that was essential to our adaptation to the dryer savanna environment.

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Whoa' date=' slow down there fella, I didn`t present it as a "Proof" or a "Theory" etc...

simply that it might be an "IDEA" to read something about it.

it presents interesting args, some of which are factual, some are disproven, some have no evidence at all eitherway. But for a well rounded research, it`s important to look at ALL reasonable args, and then try and glean Some sort of verifiable truth from them.

 

you should keep reading that site! and then you should read the site that Swansont gave you too, between them you WILL learn something :)

 

and that`s what it`s ALL about isn`t it?[/quote']

 

Meh, my biggest imperfection is my inability to control my thoughts into racing into assumptions and conclusions. :-(

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In response to that "armpit" question, I recall reading a theory somewhere that bacteria living in the armpit hairs of early humans fed on sweat and released a waste that acted as either a pheramone or a chemical marker for territory...Perhaps those bacteria are no longer with us due to human migration?

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In addition to Lucid Dreamers explanation, there was also the formation of housing. We could now shade or warm ourselves with more advanced shelter every generation. This slowly ruled out hair as a natural survival variable. But of what's left, such as armpit hair, are for sexual reasons, I believe. the armpit releases heavy amounts of sexual hormones, and the hair acts like a flower holding pollen.

 

I can't explain the hair on our heads, but who knows, we may be completely bald in 500 years. Execept for those people that look like the offspring of a cave man. :)

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...I can't explain the hair on our heads' date=' but who knows, we may be completely bald in 500 years. Execept for those people that look like the offspring of a cave man. :)[/quote']

 

Ugh... Ever notice its always people who are balding/bald who make that statement? Seriously, sexual selection. Unless some 500 year fad occurs where women find balding men more attractive then a full head of hair, throughout the entire genepool I fail to see how this will occur. Maybe I dont understand genetics too well, but from what I understand balding will only occur if we breed it in or disease it out. :confused:

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I have been aware of the acquatic ape theory for some time. It has some compelling aspects to it and for me gels well. It may or may not be valid. I'm not sure. What I am sure is that it was far too large a paradigm shift to be accepted from someone outside of the anthropological community.

 

While I think *some* aspects do look nice, it's not actually very compelling as a whole, since one would expect numerous other adaptations in an aquatic species (webbed feet, for example) that are not seen in humans. I do, however, place a lot more creedence in the idea of our ancestors are beachcombers and foragers of fertile coastal lowlands. IIRC, coastal movements actually account for some of the movement data of our species better than overland movements could.

 

Mokele

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