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My sister and I were musing this afternoon on the strange fact that humans are one of the very few naked animals. just about everyone else has fur, scales, or feathers.
Other than pachyderms and worms and those naked cats, what other animals are naked?
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I doubt that the naked cats and naked mole rats have invented fire, so I vote for warmer climates.
But then again, animals that live in warmer climates also have fur. Maybe it has a relation to how much time they spend in the sun? I know that naked mole rats live underground.
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I immediately flashed to Sam the American Eagle on this one: "Those cute little kitties and puppies? Underneath their fur, all NAKED! And it's not just the quadrapads, either. Oh, no. Underneath our fine feathers, we birds...
Would somebody hand me a bathrobe?"
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Nakedness also makes it easier to stay parasite-free. Though obviously that's not the main reason why we have no fur and other mammals do.
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Actually, it's not really that strange a fact at all that we're hairless... We developed in pretty much the same hot environment that elephants and rhinos and hippos did. We have no hair because it's easier to lose heat by evaporation that way. We also have an incredible ability to sweat (up to 12 litres a day, if the water lost can be replaced!). Even in modern populations, children who grow up in hot environments undergo a kind of developmental acclimatization and develop a denser distribution of active sweat glands. And there's the old taller/thinner people in warm environments and shorter/stockier people in cold environments adaptation too. We'd have to invent clothing and discover fire and technology before we could have moved to any colder environments, but we'd likely have lost our hair long before that point. We're pretty well suited to survive hot environments still without technology so long as there's enough water but we'd never make it up north without clothes. Huh. And now the running scene from "Atanarjuat: The Fast Runner" is going through my head... There's tonnes of neat little hot/cold adaptations we've got actually.
Oh, and I read somewhere a while ago that donkeys can drink 8 litres of water in one or two minutes to keep from heat dehydration! I don't know how true this is, but it really impresses me! Has anyone else heard this?? I guess it's not really...common...conversation topic for most people, perhaps...
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In The Naked Ape, it is conjectured that humans are mostly hairless because we come from a marine background. Most of the non-furry mammals are either marine or spend a lot of time in the water -- whales, dolphins, hippoes, pigs, etc..
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Except we do have hair all over us... tiny tiny hairs all over. Just look at your arm or leg...and of course that big mop on top of our heads.
I bet clothing was a reason for our hair loss. And as for warm climates...what about the pale Euro breeds of the North?
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Actually what really interests me is why men have beards and then loose the hair on top of our heads? What's the reason for that?
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Huh. That's...different. I hadn't ever heard of that theory, to be honest. My first impulse is to call it largely crock simply because I've been taught in the savannah theory, but there's some interesting points. There are some major problems with the way it's presented and things that are left out that make me wary though. For instance...
quote:It has been suggested that humans became hairless "to prevent overheating in the savannah" ...[or] "to facilitate sweat-cooling". But again many species resort to sweat-cooling quite effectively without needing to lose their hair.
That's nice. Good for them. In humans, however, the zone of thermal neutrality ranges over only a few degrees, in contrast to much wider zones in other non-technologically adapted mammals. We're wired (with our big brains) to work at maximum efficiency very near our top temperature limit. This would necessitate a need to have different, efficient cooling systems. Evaporation is our main way of doing this, and hair loss directly increases our ability to do this. Funny, they don't mention any of that.
quote:One hypothesis used to be that they first developed big brains and began to make tools, and finally walked on their hind legs to free their hands for carrying weapons. But we now know that it was bipedalism that came first, before the big brain and tool-making.
However, if their habitat had become flooded, they would have been forced to walk on their hind legs whenever they came down to the ground in order to keep their heads above water.
What?? NO mention of one of the main, basic points of many of the bipedalism theories which is that bipedalism evolved because humans needed to carry not tools but *food* they had gathered from the savannah back to their homes? We would then be pre-adapted to also carry tools, yes, once we started making them, which would prove useful. Also, as a side note, primates use tools too. Chimps fish for termites and other primates can use rocks to smash nuts open, etc.
Overall, it's an interesting theory, though I don't think I personally will go for it just yet. I'm all for new theories, but in regards to this site at least, I think they need to do more than give a simple explanation that supports their theory by largely ignoring or trying to discredit all the other possibilities and evidence out there.
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quote:And as for warm climates...what about the pale Euro breeds of the North?
Errrm...what about them? Sorry, not sure what you're referring to, or if that was aimed at my post above or not!
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I got started on this topic when I saw a horse that I then described as "white with black hair." Upon reflection, I realized that he had more white "hair" than black "hair," and got all puzzled as to why horses have hair and then have hair.
OK, going to bed...
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quote:A study of 117 male members of the brainy society Mensa (you have to have an IQ of over 140 to join) showed that Mensa members had a tendency to thicker body hair - and the most intelligent had hair on their backs as well as on their chests
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First, the picture of that hairless dog is hilarious and kind of scary at the same time because it reminds me of a person!
Second, Annie, I'm finishing up a degree in physical anthropology/archaeology so that's where I know this stuff from. I'm no expert certainly but any anth programme will cover all the basic evolutionary theory. I also did a big project last year on heat/cold adaptations and got really interested.
Third, aspectre, yeah, there's a lot of arguments against the AAT to be made. Largely, as I and your link pointed out, that they simply ignore evidence to the contrary or change around meanings of previous theories to argue their own, and that in itself destroys the basis of their argument. Let alone that most of their pro-AAT arguments don't actually work.
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That's really interesting, FG. I wonder what the correllation is. I would think that maybe it's ethnic. Maybe hairier ethnic groups are smarter for other reasons. Or maybe the real purpose of hair is to store extra intelligence. I think I'll choose to think of it that way.
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Funny, all my super-genius nearly-retired profs are mostly bald. At least the male ones. I guess all their intellihair is on their backs or something. Eeeeauugh! Bad mental images! *runs away to hide*
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quote:First, the picture of that hairless dog is hilarious and kind of scary at the same time because it reminds me of a person!
Is there some evolutionary value to having a distinctive feature that separates us from other mammals, giving us an easy means of identifying other humans as being different from most primates? I'm just thinking that if a hairless mammal naturally "looks human" to a human, that may be significant ... somehow ...
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quote:Is there some evolutionary value to having a distinctive feature that separates us from other mammals, giving us an easy means of identifying other humans as being different from most primates? I'm just thinking that if a hairless mammal naturally "looks human" to a human, that may be significant ... somehow ...
Apparantly so. There's a lot of speculation that the horns and shields on treceratops and similar dinosaurs are for ID purposes moreso than defense. Same with antelopes who travel in herds with very similar species.
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First of, Telporion, thats pretty scary. Secondly we all have hair, as do all mammals, its fur were short of.
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quote: A study of 117 male members of the brainy society Mensa (you have to have an IQ of over 140 to join) showed that Mensa members had a tendency to thicker body hair - and the most intelligent had hair on their backs as well as on their chests
Or that hairy guys are more likely to join Mensa if they qualify. I have a hairy guy, but he's not a member of Mensa. I don't actually know any members of Mensa.
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I could be mistaken, but I think that whales really do lack hair, except while in the womb. But they're more or less alone.
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