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Author | Topic: Is body hair a functionless vestige? | |||||||||||||||||||||||
RAZD Member (Idle past 1433 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi again Ken Fabos,
... My understanding is that it's not the number of hairs that's widely variable, ... Curiously, I looked into this when putting together Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution, see Message 41:
quote: ... just their size - but I could be wrong. Anyone know? ... Not the size, really, but the developmental stages are interrupted at a younger stage. Again from Message 41:
quote: I also note that this sexual selection is still continuing, as the prevalence of shaving of body parts shows. Enjoy. we are limited in our ability to understand
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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dennis780 Member (Idle past 4804 days) Posts: 288 From: Alberta Joined: |
Actually, I think you have 'jumped the guns' so to speak on this subject, in saying that hair provides little to no insulation for an animal. This just isn't true.
In fact, in 2004, Harvard students shaved a camel, and found it's water loss due to sweat increased by over 30%. As well, it would seem logically correct, since physically most animals living in warmer climates have fur, such as Zebras, Giraffes, Lions, Tigers, Apes, Monkeys, Oxen, Antelope, horses, cows, hyenas, etc. You get the point. There are many reasons that contradict apes `evolving` from quadrupeds to bipeds, losing their fur, etc. But I think for this particular subject, this information seems relevant. Dennis.
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RAZD Member (Idle past 1433 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi dennis780, and welcome to the fray.
In fact, in 2004, Harvard students shaved a camel, and found it's water loss due to sweat increased by over 30%. Citation please? Did the camel maintain the same body temperature?
There are many reasons that contradict apes `evolving` from quadrupeds to bipeds, losing their fur, etc. ... Oh? Care to start a new thread on this? Go to Proposed New Topics to post new topics. Enjoy.
... 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 formatting questions when in the reply window. For other formatting 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 formatted with the "peek" button next to it. we are limited in our ability to understand
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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Ken Fabos Member (Idle past 1269 days) Posts: 51 From: Australia Joined: |
RAZD, that did sound a lot like what I said - numbers the same, hair size different and evolution didn't add more follicles in line with increasing size, nor produced thicker heavier hairs. Whether true across the whole human spectrum would still be a question. Seems like the size of those vellus hairs, by whatever mechanism, has reduced, even to the point of near invisibility, but not universally. Seems (from my layman's perspective) likely we've seen hormonal variations to growth of hairs - which is likely to have been evolutionarily easier - rather than actual loss of follicles. But the loss of those hairs completely would take away an array of sensory mechano-receptors that are still potentially advantageous. Can there be evolutionary advantage in reducing our sensory sensitivity? Does a heavier pelage make for more or less sensitivity - or just sensitivity to different kinds of stimuli. eg, longer hairs might be better at detecting air movements and shifts in breeze than shorter lighter ones and lighter ones more able to detect small insects. And does hair held erect by goosebumps transmit those tactile sensations better than in it's relaxed state? They'd be held tighter. Also not sure what adrenalin and the like do to our sense of touch, whether by direct skin contact or through our hairs; increased sensitivity doesn't sound impossible.
There's a lot we don't know and should if we are to make informed speculation about the evolutionary process that's made us how we are. On shaving I wouldn't think that people plucking and shaving counts in the sexual selection of relative hairiness; even if reduced hairiness is a measure of attractiveness in the modern context those practices are likely to prevent the selection for reduced hair by giving false impressions. Hairy girls can still get the guys, just keep on plucking!
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Ken Fabos Member (Idle past 1269 days) Posts: 51 From: Australia Joined: |
Hi Dennis. From my perspective functionality with respect to thermoregulation seems very likely, however it must be highly variable as our hairiness is highly variable. I'm hairy enough myself to believe that it can still provide me some insulation from the cold, a smallish amount primarily when at rest in the absence of breeze, by impeding but not stopping air flow. Cooling? See my earlier comments, but sparse human body hair allows air flow across bare skin even if sometimes thick enough to impede it.
Rather than having jumped the gun myself, I think others have; I was commenting on what I believe to be a widespread meme, one I think is overdue for debunking. My own focus remains the sensory function which I think is a serious ongoing omission; whilst I haven't gone through every thread here, I have looked through a lot of discussions of human 'hairlessness' and sensory function looks especially conspicuous by it's absence.
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Dr Adequate Member (Idle past 313 days) Posts: 16113 Joined: |
I read recently (I think in a book on supernormal stimuli) that the places where we do get hair are also the places where chimps get it first.
So the distribution of hair in humans could be the side effect of a (hormonal?) adaptation towards neoteny that had nothing to do with hair as such but was favored for its effect on something else, such as brain plasticity. It would be what Gould called a spandrel.
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dennis780 Member (Idle past 4804 days) Posts: 288 From: Alberta Joined: |
Thanks RAZD. I'll try using the quote thing there...lol. I'm old school you know.
Citations for Camels water loss: Camels - All About Camels Facts, Information & PicturesCAMELS Free Website Building Software | Create a Website - Homestead Although these sites seem to say 50%. It's been a few years since I first read about it so I am probably mistaken, and they actually sweat 50% more. And no, I don't care to start a new thread. I just started on this a few hours ago, and don't have enough time to answer the threads that alread exist. I'm sure there is a thread discussing the various subjects....plus I don't know the first thing about starting a thread. The study of evolution and creation is just a hobby for me, and hobbies are supposed to be fun. I much prefer to jump into conversations unannounced and blurt random facts. This is fun.
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dennis780 Member (Idle past 4804 days) Posts: 288 From: Alberta Joined: |
Another point to notice is that generally humans grow hair where apes do not. the face and chest are prime examples, since apes are hairless there, or sparse, but humans (especially males) grow hair in these areas. Even female humans grow chest hair and nipple hair (as much as we would like to ignore it, lol).
I'm a little confused as to the sensory point. It's unclear to me how this would be an advantage or disadvantage either way. More detail??
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Dr Adequate Member (Idle past 313 days) Posts: 16113 Joined: |
Another point to notice is that generally humans grow hair where apes do not. the face and chest are prime examples, since apes are hairless there, or sparse, but humans (especially males) grow hair in these areas. Well I'm not sure that this is particularly sparse as compared to a human.
Sparse compared to the rest of the chimpanzee, perhaps. But to suggest that we "grow hair where apes do not" seems unjustified.
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dennis780 Member (Idle past 4804 days) Posts: 288 From: Alberta Joined: |
"Well I'm not sure that this is particularly sparse as compared to a human."
I'm not comparing, I'm pointing out that apes are MORE hairy everywhere but their face and chest. This is the opposite with humans. thats one hairy ape, how long did it take you to find that one pic of a monkey with a hairy chest? Cause I found lots to show they are FAR more sparse on their face and chest:KODAK | Imaging Innovations for Business http://www.kuvamaja.com/..._Park_ape_straw_8X10_02720096.jpg Wild About The World Coming Soon Page Just a moment... http://liliendahl.files.wordpress.com/2009/10/gorilla.jpg Page not found - Green Diary - A comprehensive guide to sustainable hacks, green tips, and eco suggestions
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Dr Adequate Member (Idle past 313 days) Posts: 16113 Joined: |
I'm not comparing, I'm pointing out that apes are MORE hairy everywhere but their face and chest. What you said was "humans grow hair where apes do not".
thats one hairy ape, how long did it take you to find that one pic of a monkey with a hairy chest? Cause I found lots to show they are FAR more sparse on their face and chest: Most of those pictures don't look that much different. Edited by Dr Adequate, : No reason given.
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dennis780 Member (Idle past 4804 days) Posts: 288 From: Alberta Joined: |
Less hair on chest and face, more on rest of body.
Humans opposite. Follow?
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Dr Adequate Member (Idle past 313 days) Posts: 16113 Joined: |
Less hair on chest and face, more on rest of body. Humans opposite. Follow? Yes. This does not support your claim that "humans grow hair where apes do not". Follow?
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Dr Adequate Member (Idle past 313 days) Posts: 16113 Joined: |
I much prefer to jump into conversations unannounced and blurt random facts. You seem to be better at the "random" bit than the "fact" bit.
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Ken Fabos Member (Idle past 1269 days) Posts: 51 From: Australia Joined: |
I'm curious if anyone here thinks the sensory function of body hair is inconsequential or lacks relevance to understanding it's evolution? Also, has anyone come across serious discussion of that evolution that includes due consideration for that sensory function?
I've been accusing the community of academics that study human evolution of (to my mind) a serious oversight. I don't mind being proven wrong, but I've struggled to find evidence that it's gotten any real consideration.
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