Why are we near hairless?

Why do humans develop nose and ear hairs when they are old? Because old people are to slow moving to keep flies out?
 
iceaura said:
There's a chicken and egg problem with positing that as the initial evolutionary driver, though. Unusually thin and patchy hair is not a sign of good health in any known animal (nor even humans, now), and hairlessness would a severe handicap in almost all land mammal niches - so how to get from Apelike to Bare?

Like the bipedal stance with its dramatic skeletal demands, the small and weak fighting teeth, the unique childbirth sequence, the bizarre larynx morphology, and so forth, unless you are willing to posit a hopeful monster of inexplicable sexual attractiveness or extraordinary survival advantage surviving a double length childhood and mate competition within a pack of chimpanzees, you have the task of providing a step by step incremental advantage to the initial stages of your now completed innovation; starting with an ape probably similar to a modern chimp, or possibly baboon.

Horses sweat, and the hair doesn't interfere much. Wild pigs are actually pretty hairy:
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I disagree with your specific point, but I agree with your general point.

If a variation such as hairlessness was sexually selected for, a creature would still be able to distinguish sickness.
This baboon is partially haired and is presumably considered attractive to other baboons, though not to my taste.
(OK, just a little bit.:))
baboonbum.jpg


Actually, this babboons rear has a very similar shape to the fruit of the coco de mer, which humans have always been fascinated with.
images


Perhaps selection for nakedness began at the genitals and spread to the whole body.

Regarding your general point.
Yes, humans are unusual in their degree of unusualness.

Bare skin. Unusual
Upright stance. Unusual
High Intelligence. Unusual
Long period of immaturity. Unusual


A theory of evolution that will explain us fully is very far off.
 
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beccause god made us that way!

No, just jerking you, I always liked the aquatic ape theory, but would like to see more evidence.
 
wise acre said:
We've had hats for a long time...why do we have head hair?
Why do we have an appendix?

Why did all races lose so much hair? Is there a correlation between climate and hair levels?
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hats only have been around for a few thousand years. that doesn't mean anything in compared to 7 million years of human evolution.

many new studies say that the appendix used to have a disgestive function in human. today, although it doesn't do anything to increase our survivability just like our pubic hair, foreskin, wisdom teeth, etc. it takes a lot longer than 5 thousand years to get rid of it.

according to wikipedia:

"The bipedal australopithecines (a genus of the Hominina subtribe) evolve in the savannas of Africa being hunted by Dinofelis. Loss of body hair takes place in the period 3-2 Ma, in parallel with the development of full bipedalism."

these primates lost their hair as they learned to walk upright. climate had very little to do with it. maybe because freeing their hands allowed them to do a lot more to increase their survivability (such as making clothes, fire, etc.) so that hair wasn't really needed to survive in the wild.
 
wise acre said:
Good point, and at least the elephants had hair ancestors, so what was the advantage?
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The link goes to an article about us evolving hair less because mothers selected the hairless children to nurture because the Neanderthal's hair offended them.

We did not evolve in the cold climate like the Neanderthal. He was there for millions of years. We invaded his territory less than a hundred thousand years ago. We evolved in Africa where we did not need fur, like the elephant didn't either.

Researches sometimes come up with any old weak theories just in order to get tenure . . .

charles
http://atheistic-science.com
 
markl323 said:
according to wikipedia:
.......
these primates lost their hair as they learned to walk upright. climate had very little to do with it. maybe because freeing their hands allowed them to do a lot more to increase their survivability (such as making clothes, fire, etc.) so that hair wasn't really needed to survive in the wild.
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That is complete nonsense.
We lost our hair because the dexterity of our hands allowed us to make clothes? :bugeye:

Please, give me body hair.
I'm sick of buying fricking clothes!
 
ElectricFetus said:
I always liked the aquatic ape theory, but would like to see more evidence.
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I thought the evidence for the aquatic ape theory was better than the evidence for the conventional out of the trees and into the savanna theory. The human hair pattern as a being the hair pattern for a wading animal was one of the pieces of evidence for Aquatic Ape theory.

I don't think there ever was any good evidence for the conventional theory of how man left the trees.
 
tuberculatious said:
why do some men get bald?
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evolution will only change you when it affects survival and reproduction. dudes reproduce before balding (if they're lucky), and the fierce reflection of the sun's fury by their chrome dome is a devastating defense mechanism. plus everyone knows bald guys punch harder.
 
ElectricFetus said:
I always liked the aquatic ape theory, but would like to see more evidence.
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nirakar said:
I thought the evidence for the aquatic ape theory was better than the evidence for the conventional out of the trees and into the savanna theory. The human hair pattern as a being the hair pattern for a wading animal was one of the pieces of evidence for Aquatic Ape theory.

I don't think there ever was any good evidence for the conventional theory of how man left the trees.
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Evolutionary theory is not my field, so I may be wrong about this. But my understanding is that the Aquatic Ape Hypothesis does not have any significant number of adherents amongst actual scientists within the anthropology or evolutionary biology fields. It seems that 99.9% of the time I ever see the phrase is on internet science forums.

Rather than an application of the scientific method, the AAH strikes me as one big thought experiment, an attempt to mentally devise an all-encompassing hypothesis for disparate human traits that can be alternatively explained. It’s certainly not a theory, as many describe it, with its selective interpretations and lack of predictive ability.

This sums up my attitude rather well....

Journal of Human Evolution
Volume 33, Issue 4, October 1997, Pages 479-494

Umbrella hypotheses and parsimony in human evolution: a critique of the Aquatic Ape Hypothesis

John H. Langdon

Department of Biology, University of Indianapolis, 1400 East Hanna Avenue, Indianapolis, Indiana, 46227, U.S.A.

Received 25 March 1996; accepted 6 March 1997. ; Available online 16 April 2002.

Abstract
Conventionally, anthropologists have sought to explain a multitude of unique features of modern humans as the outcome of a single adaptive breakthrough. These “umbrella hypotheses” are aesthetically appealing because they appear to be parsimonious. As internally consistent hypotheses about the past, they are very difficult to prove incorrect in an absolute sense. Anthropology has often rejected them by consensus without developing explicit reasons. This essay explores one example of these models, the Aquatic Ape Hypothesis, the proponents of which continue to argue that they have not received a fair hearing among anthropologists. The hypothesis is troubled by inconsistencies and has not been reconciled with the fossil record. More importantly, its claim to parsimony is false. The numerous “explanations” for individual anatomical traits that it generates constitute premises that are not better founded than competing terrestrial “explanations”. The unifying theme of aquatic adaptation is considerably less parsimonious than the assumption that our lineage has always been terrestrial. Finally, the mosaic pattern of hominid evolution demonstrated by the fossil record will not support this or any single cause theory. Most of these criticisms have been previously voiced in one form or another, yet umbrella hypotheses ranging from mainstream science to the paranormal maintain their popularity among students, general audiences, and scholars in neighboring disciplines. One reason for this is that simple answers, however wrong, are easier to communicate and are more readily accepted than the more sound but more complex solutions. Evolutionary science must wrestle with this problem both in its own community and in the education of the public.
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Human skull hair and men's facial hair grow continuously, there is no other example among animals. This is common among people and we know that all people around the world (apart from some African people) have common ancestor who left Africa around 70 000 years ago. Major hair mutation must have been completed while we were still in Africa.
If we can cross-breed dogs and cats after numbers of generation, to get an hairless ape society wouldn't take so long. Problem is, this hair revolution should have been occured not less than 100 000 years ago before domestication (agriculture) revolution. Something else was going on. Humans somehow developed an idea about selection within their species to favour less hair in some parts of their body, while eliminating others. Our appearance is not the result of a natural process; it was designed by some stone-age hair experts. Maybe they all applied their medicine-man's receipe.
 
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hercules said:
Evolutionary theory is not my field, so I may be wrong about this. But my understanding is that the Aquatic Ape Hypothesis does not have any significant number of adherents amongst actual scientists within the anthropology or evolutionary biology fields.
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It's been rejected on bad grounds, as well as propounded on bad grounds.

It was first advanced as a sort of cure-all - supposedly settling a whole range of questions. When that proved unlikely, it was rejected entirely, and with no better sense.

The standard explanation of human evolution, the one that is supposedly supported by the fossil record etc, doesn't add up. The fact that everything is not explained by some kind of incipient dolphinization does not improve the standard account, which fails to plausibly handle several major features of human anatomy as well as the apparent timeline.

You can't simply drop a chimp on the savannah and have it adopt hind leg walking for a million years until it gets good at it. You'll get a baboon, not the only non-hopping bipedal mammal. You can't have hairless humans trying to make it through the freezing, fly and bug-ridden svannah night without clothes and fire and a high quality diet - and why the perfect adaptation to fish and clams and such? Even raw? The throat morphology of humans is really strange - and it's only good for talking hundreds of thousands of years after it starts becoming what we have now. Our teeth and jaw are not capable, especially not for the fifty years we seem to be designed to live, without tools. What drove all these changes?

Myself, I like wading for food as the driver for bipedal stance, the fat layer, the throat morphology, and possibly the intelligence initially. I like the heat warrior and climate change driver for the hairlessness, the tool use (beginning with the carry bag and netting), fire adoption, greater intelligence, the opposable thumb, and refinement of the bipedalism - including the pelvic changes allowing large head childbirth. And I like the feedback from the tool and foraging expansion and thumb to explain the brain explosion, which in turn drove the language exaption of the throat stuff.

But all of that is pure speculation. The point is, the current standard account makes no more sense than the aquatic ape guess, and in some cases less. Rejecting the wading stage because there are no fossils, for example, is silly - that's poor fossil making environment, and a rare event in one place long ago. By the time we have fossils, they're already up on two feet hitting things with rocks and walking all over the place in many environments and with varieties, suborders, species, etc.
 
Captain Kremmen said:
That is complete nonsense.
We lost our hair because the dexterity of our hands allowed us to make clothes? :bugeye:

Please, give me body hair.
I'm sick of buying fricking clothes!
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it's only nonsense to those who fail to understand how evolution works.
 
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