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Junior Member (Idle past 5872 days) Posts: 12 From: Schererville, IN Joined: |
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Author | Topic: why is the lack of "fur" positive Progression for humans? | |||||||||||||||||||||||
RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
We're runners. One hunting strategy is to chase the animal until it collapses. We can run over long distances whereas animals with fur coats overheat and drop from heat exhaustion. Which explains why all the animals in Africa are covered in fur, and the male human is hairier than the female. Or are you saying that humans can run faster than animals and women did all the hunting??
Ever see someone out jogging with their dog? The jogger sweats over the entire surface of his body and is thus able to throw off excess body heat over the entire surface of his body. The dog can only throw off excess body heat through his tongue and the pads on his feet. If the jogger isn't careful, he could easily run his best friend to death, especially on a hot day. Ever tried that with a horse? Sorry but this "explanation" just does not add up. Enjoy. Edited by RAZD, : dimorphism is part of the equation Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
This process was probably propelled by increases in body size and activity levels associated with modern limb proportions and striding bipedalism. Which doesn't explain the sexual dimorphism in hairiness. It was probably more likely propelled by sexual selection for younger more childlike appearance in mates. See Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution for another view on this subject.
This process was probably propelled by increases in body size and activity levels associated with modern limb proportions and striding bipedalism. I wouldn't be surprised to find that the first hominid ancestor that was "bare" appearing predates the formation of the savanna ecology in africa. Enjoy. Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
... what did we gain from the loss of fur that allowed the less hairy ancestors more able to survive. It may surprise you to learn that we have as many hair follicles as a ape would have for our body size. See Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution - Addendum #1, Human Body Hair and Female Pattern 'Bareness' quote: What is different is that the hair does not mature beyond childhood (vellus) hair for almost all females and major portions of males. Mature (terminal) hair grows on the head, pubic and armpit areas on both sexes and on the face, chest, back and arms on males. What we see is that that female skin areas are covered with vellus hair, rather than terminal hair. Male pre-pubescent youth skin areas are also covered with vellus hair, rather than terminal hair. Sexual dimorphism points towards sexual selection being a factor. Retention of youthful characteristics into adulthood (neoteny) is well marked in human evolution, in facial characteristics (especially jaw and teeth) compared to other apes and in the long time it takes for humans to reach maturity after becoming sexually able. This is either another example of neoteny in humans or it is the raison d'etre for neoteny (ie sexual selection for younger appearing females). Enjoy. Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Of course, horses sweat over their entire bodies. So sweating explains bare appearance in humans how? This concept of hair - sweat is a tie over from the old "savanna" theory of human bipedalism. Now that we know that bipedalism evolved before the savanna ecology this theory has been discredited. Now go back and rethink the bareness issue. Enjoy. Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Not faster, but farther. Take for example, the cheetah, which is the fastest land animal. In a 100-yard dash, it would beat us hands ... er ... paws-down. But who would win a 1-mile run? The difference here is the human brain not the fur\bareness. Delayed gratification. The cheetah is the ultimate get-it-now-or-give-up approach, one you will see in many other animals. What makes humans, wolf packs and similar hunting behavior different is backing down from all out running and being able to track the prey. You can walk a deer down.
Remember also that the excess body heat I'm talking about is generated by the act of running. Not just from walking about in the noon-day sun, but from running. Which again points to the women being the runners then. Half the hair of men. The fact that there is sexual dimorphism in human hairiness shows you where it is being selected - in the sex with the more pronounced expression of the trait. Next look at a few porn websites for unnaturally hairy women, naturally hairy women and unnaturally bare women. Look at ads. Look at the ever hair growing market for hair removal products and tell me that there is not ongoing sexual selection for bare appearing women. Why does googling "hairy women" produce websites of naturally hairy women versus ones with unnaturally shaved arms, legs, etc.? And this has nothing to do with why we are bare. What you may be looking at is the fact that the pre-adaptation for bareness while still in the forest-jungle ecology allowed this ability to develop and not the other way around. Running does not explain sexual dimorphism. Sex does. Sex made us human. Enjoy. Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Ever see a wolf Pack hunting? Deer running? It's called cursorial hunting:
quote: None of which needed to evolve bareness to hunt in this manner. Enjoy. Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
But we are talking about survival advantage and fur. Or the breeding advantage of apparent bareness ... to the point where it threatened survival and clothes had to be invented for it to continue ... Enjoy. Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Another author points out that it is unusual in sexual selection to have the same trait selected for in both sexes. It isn't. It is selected in women, males just inherit it. Look at the variation in males versus women. Women - nearly all similarly bare, a disease with "male pattern hair" is a dreadful thing requiring treatment, just having a "mustache" is undesirable, trait heavily selected. Men - from nearly bare to covered in hair, all having little trouble finding mates, trait not selected at all. Enjoy. Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
The context would tell you what And what I was pointing out to nator was horses sweat but have not evolved to be bare. Being able to sweat and being "bare" is a post hoc ergo propter hoc fallacy, not an explanation. You also have elephants - that are bare but don't sweat, nor are they known for running down prey.
A further thought about running occurred to me, ... by freeing our own ribcage from the stresses of running on our forelimbs, thus freeing us to suck air in at whatever rate we need. ... and if you ask nator about that she will tell you that horses have coordinated their pace so that the act of running pumps oxygen through their lungs without needing regular lung muscles. That's an adaptation for running. Horses have also evolved an extra pump in each foot that pumps blood back up the leg when running. That is an adaptation for running. The "savanna" running theory does not explain why women are less hairy than men, and without being able to explain that strong dimorphism there is a big whopping giant imploding hole in the argument. This is just a hangover of the 'savanna bipedal theory" that is almost completely discredited now because it cannot explain the evolution of bipedalism before the savanna ecology. Nor does it explain the sexual attraction of bare skin. Enjoy. Edited by RAZD, : the elephant in the room Edited by RAZD, : . Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
That still doesn't address the initial reason for sexual selection. Why allofasudden is nekkid pretty? Yet it is indisputable that bare nakedness is very integral to sexual attraction in humans. This gillette ad for instance, "Venus - Inside Every Woman" is not about shopping for food. It's about how to be unnaturally bare in order to attract a mate. I also don't think it was "sudden" but may have been a part of "hominid" features a very long time ago. Nor are we alone ... (1st picture originally from What's on at Bristol Zoo | Bristol Zoo ) (2nd picture originally from What a babe!) ... it's just expressed in humans to the point of endangering survival (why we need clothes eh?), which is an indicator of Fisherian Runaway Sexual Selection, not of selection for fitness to an ecology. Personally I think apparent bareness evolved before the savanna ecology, for reasons that I have laid out in Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution and specifically on message 65 of that thread.
quote: The savanna ecology would have greater temperature swings between day and night than a jungle-forest ecology. Enjoy. Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
I was using horses to show that sweating and running are not necessarily linked.
Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Small point\quibble
Lastly, perhaps hairlessness was in fact an advantage ... We are not hairless nor even have fewer number of hairs than an ape our size should have, what we have are less developed hairs. Where we see apparent bareness the skin is covered with vellus hair instead of terminal hair, especially on the female
One reason, using the Handicap principle, may be that, like the peacock's tail, not having hair is selected for because it is disadvantage. A female that can stand the temperature changes is obviously very healthy (or very capable of making clothing, shelter or fire), and hence would be a good potential mate. Or because the female looks younger, more like a child than an adult capable of reproduction, they are more protected and cared for, thus giving their offspring an advantage. Enjoy. Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
welcome to the fray, entityUnknown
In the aquatic theory, it states that our ancestors spent a signifigant amount of time in water to eventually obtain useful adaptions, the lack of "fur" being one. Except that we don't lack "fur" -- we have about as many hairs per sq.in. per lb as chimpanzes. The "aquatic ape" theory also does not explain sweat glands.
The aquatic theory compares us to aquatic mammals, such as the whale, dolphin, hippo, etc. Which don't sweat, whales and dolphins don't have any hair, and which doesn't include pigs, rhinos and elephants, while hippos feed out of the water and sleep in it.
This is not directly related to the question, but it also explains why our fat is attatched to our skin, like the blubber in seals. And like pigs and other animals.
For the thermoregulation hypothesis, it simply doesn't add up. If we went to the savannah and shed our fur coat to better regulate our temperatures, Agreed, but for different reasons: one would expect the "hunter" side of the sexual dichotomy to be more adapted (less visible hair) than the "gatherer" side, when the opposite is true. It also does not answer the question of night time temperatures, or fur acting as insulation against heat as well as cold, a problem that is even more chilling when you are wet. The answer is that the evolution of our hair to be mostly vellus hair, especially in the female, likely occurred before these ancestors ventured out into the savanna, and that the savanna had nothing to do with it. This matches bipedal hominids diverging from chimps before the savanna climate developed. This also matches gorillas having bare skin areas even though they never left the jungles.
... why aren't there other "naked" animals? There are, and pigs and elephants are some examples.
In reply to the sexual preference suggestion: why would we be attracted to naked apes in the first place? Other terrestial animals don't seem to have a problem with furry mates. An argument from incredulity. The facts remain that (a) less visible hair is much more marked in women than in men, sexual dichotomy on any trait being a sign of sexual selection, (b) this preference for more naked appearing women is ongoing, even today, in ads showing bare hairless legs etc, and in the virtually total naked skin in porn, (c) pattern nakedness is also common in apes to mark sexual readiness, (d) other apes have bare areas, and the differences if fur patterns often marks the division between species (ie - provides visible signals for the choosing of mates), and (e) is the only explanation that stands up to all the evidence. For more discussion of sexual selection in humans see this thread Enjoy.ps - as you are new, some tips: type [qs]quotes are easy[/qs] and it becomes:
quotes are easy or type [quote]quotes are easy[/quote] and it becomes:
quote: also check out (help) links on any formating questions when in the reply window. For other formating tips see Posting Tips Edited by RAZD, : . by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hello arrogantape, and welcome to the fray.
The problem with the savannah explanation is it is merely conjecture, ... The "Savannah" theory at least has some evidence from the change in climate to support it, however this evidence is now seen to contradict it. Why? because the fossil evidence now shows that bipedalism evolved before the Savannah developed. What we have is a pre-adaption to bi-pedalism from living in an open forest environment that allowed mixed walking and climbing behavior, and then when the trees went away, the apes that survived the transition were already walking. Curiously fur and sweat are NOT good arguments for the savannah life: almost all other animals that live there have fur. Some of these animals are also cursorial hunters (jogging and walking down prey that they track over long distances). Again, it could be argued that bipedalism enable cursorial hunting rather than the other way around, and that sweating evolved as a result.
... as is the aquatic origin. ... Which fails to explain why animals that have been aquatic for a lot longer than humans have existed are still furry: seals, otters and the like, animals that also maintain a living ashore, nor why (some) pigs and elephants have less hair than humans, and as you say, horses sweat, and they are not naked. Thus we can establish no link between any specific behavior and the degree of fur, and claiming it is due to an aquatic phase is just post hoc ergo propter hoc assumption.
What you have to do in this case is line up points of evidence. Here are some hints: (1) sexual dimorphism shows that females are more naked appearing than males. This is particularly devastating to the "Savannah" theory because the ones doing the cursorial hunting were the males while the females stayed in brush gathering fruits and tubers (or we got that all backwards eh?). It also is devastating to the "Aquatic" theory because we see no dimorphism in fur cover for any other semi-aquatic animals. (2) sexual selection account for sexual dimorphism as a general rule, and Fisherian Run-away Sexual Selection accounts for some otherwise bizarre features, like peacock tails. (3) two adaptations to changing temperatures (night-day, summer-winter) are fur and subcutaneous fat. The fat is an adaptation for controlling body temperature not to water. (4) the climate back then in Afar and surrounding area was very different from today, much milder and much less temperature swings. Personally I think that the bipedal apes were already adapted to bareness via sexual selection and that Lucy was likely naked. I also think that clothes and body painting developed from camouflage for hunting and hiding, and later became converted for mating behavior (I believe we still see some examples of this). I also believe that the maximum sized brain evolved as a result of mating behavior and sexual selection. However, these are my personal opinions. See Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution for another thread on this topic. Enjoy.ps - as you are new here, some posting tips: type [qs]quotes are easy[/qs] and it becomes:
quotes are easy or type [quote]quotes are easy[/quote] and it becomes:
quote: also check out (help) links on any formating questions when in the reply window. For other formating tips see Posting Tips If you use the message reply buttons (there's one at the bottom right of each message):... your message is linked to the one you are replying to (adds clarity). You can also look at the way a post is formated with the "peek" button next to it. Edited by RAZD, : clarity by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Thanks arrogantape,
... the female human being more hairless than the male rather shoots down the Savannah folks, but maybe not. Certainly millions of years of development can bring out interesting sexual dimorphism. True, but the fossils do not show any great change in the size dimorphism, so sexual selection was already underway before the earliest bipedal hominids, similar (but not as extreme) as we see in gorilla (interestingly with bare chests on males, and chests on females that lose hair when the milk-feeding young). Certainly sexual selection for more and more hairless females is still going on (the razor industry is alive and well, and it is a rare porn site that shows hair ...)
... larynx migration ... Which makes vocalization possible. If we consider mating behavior to be a driving force in humans as it is in other animals, then we have to look at the possibility of song, dance, music, art, all being derived from mating behavior (mating songs are common, mating plummage is common, many animals have mating dances, etc). Selection for singing could result in larynx relocation with getting a toe wet. Dancing also accounts for long legs. Just as a measure of possible selection systems, look at who are considered sexy today: singers, dancers, musicians, artists. Not: runners, swimmers, philosophers, mathematicians, nobel prize winners, (etc).
You hit the nail on the head when you mentioned the wet environs of our earliest hominids One of the (many) theories of early hominids is that they migrated south along the western shores and then back to Ethiopia area, following the supply of tubers in swampy ground. Certainly they covered a lot of ground, but I don't think they were committed to any single foraging pattern, but likely to be opportunistic for wherever they were.
... mixed up nudy savannah hominids ... Why do you assume that they would be mixed up? Or that the chimps would accept you (they have been known to kill other chimps over territory). Enjoy. by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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