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Old 07-15-2010, 01:54 PM   #81
Shane Skowron
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Re: Study finds correlation between C.O.G. and Speed

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Originally Posted by Aushion Chatman View Post
I still say that skin tone being darker in the tropics is a VERY weak reason for (especially) humans to have selected darker skin in those regions. Even animals with limited brain capacity (lizards, snakes) have the survival capacity to dig or seek shade when the sun is blazing.
Ancient humans didn't have the luxury of hiding whenever it got hot. It wasn't until like 200 years ago that people did anything after dark, for safety and practical reasons. Hunting and gathering all to be done during the day.

Persistence hunting works because animals overheat when they run, whereas humans do not. I can't help but think that in the areas where they do/did that the most (African plains), they would have adapted to that a little better.

How do you explain different amounts of body hair for different populations? What about different sweating rates?
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Old 07-15-2010, 02:30 PM   #82
Steven Price
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Re: Study finds correlation between C.O.G. and Speed

Homo sapiens emerged as a recognizable species at the earliest 200,000 years ago in sub-Sahara Africa. Prior to this its earlier ancestors survived in savannas, as did early Homo sapiens. When small groups moved out of Africa approximately 50,000 years ago evidence is that they moved into the mid-east. They then moved east and then north and back west. The point is that during long periods (100,000 years at a minimum or say 7,000 generations) H.s. was in regions of very poor tree-cover and was highly "exposed." The theory that skin color evolved to protect from UV damage/Vitamin D production, etc., seems very compelling.
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Old 07-15-2010, 05:33 PM   #83
Aushion Chatman
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Re: Study finds correlation between C.O.G. and Speed

See this is where it becomes pseudo-science to me...

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Ancient humans didn't have the luxury of hiding whenever it got hot. It wasn't until like 200 years ago that people did anything after dark, for safety and practical reasons. Hunting and gathering all to be done during the day.

Persistence hunting works because animals overheat when they run, whereas humans do not. I can't help but think that in the areas where they do/did that the most (African plains), they would have adapted to that a little better.
This is very easily refutable by the fact that the Saharan hasn't always been a wasteland, it is generally accepted scientific fact that the Saharan was once lush and received ample amounts of rainfall for vegetation and animal life, perfect for nomadic ancient man to settle down in.

I DO have a problem refuting this from one standpoint though because I do not believe in macro-evolution, meaning I don't believe there was a transition from ape to man...therefore there was IMO never a time where humans didn't have the brain power potential for the problem solving skill we possess today.

However, let's go one step further..suppose the lighter folks figured out, hey this sucks for us, we get skin cancer and die, now that the Saharan is more desert-like... (I highly doubt skin cancer was high on the list for reasons to die for ancient humans, but we'll pretend it was). So they decided to move to cooler climates...How then has any form of selection played ANY part. It was simply, survival tactics, not some mechanism that took 1,000's of generations...It may have taken 1 generation to pack up say good-bye and move. A feudal war based on "race" could also have played a part...who knows? There are many reasons that could be the answer to why you find lighter skinned folks in certain areas and darker in the other...

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How do you explain different amounts of body hair for different populations? What about different sweating rates?

Here's the problem..there is NO tangible life or death advantage to having more or less hair...just like Vitamin D production, just like uV ray protection.

This is what always bugs me about the pseudo-science side of evolution...

What does having more hair on your body have to do with anything other than variation? This is insane logic to me, we're talking about advantages and disadvantages that MUST necessarily be near the precipice of life and death... Any genetic variation that is not life and death and is merely a benefit for comfortability, is not enough to deselect or select a trait. Why would sweat rates have anything to do with real survival...maybe comfortability.

Before you say people overheated back in the day...Think again about what the saharan was like for a very long time...and think also that the sweat rates as measured today may or may not be the same as what you would measure then...so you are applying observations of us today, to a population that if selection is true, could have had some vastly different genetic traits then we do.
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Old 07-15-2010, 05:35 PM   #84
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Re: Study finds correlation between C.O.G. and Speed

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Homo sapiens emerged as a recognizable species at the earliest 200,000 years ago in sub-Sahara Africa. Prior to this its earlier ancestors survived in savannas, as did early Homo sapiens. When small groups moved out of Africa approximately 50,000 years ago evidence is that they moved into the mid-east. They then moved east and then north and back west. The point is that during long periods (100,000 years at a minimum or say 7,000 generations) H.s. was in regions of very poor tree-cover and was highly "exposed." The theory that skin color evolved to protect from UV damage/Vitamin D production, etc., seems very compelling.
this is news to me and directly opposed to what I was taught. I was taught that man migrated to different areas specifically for reasons of finding food and areas where rainfall and vegetation were plentiful.

You seem to be re-writing some things I considered fact. Are you saying that H.s. simply decided to stay in a barren wasteland for 100,000 years before figuring out he could migrate?
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Old 07-15-2010, 05:39 PM   #85
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Re: Study finds correlation between C.O.G. and Speed

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Does anyone have steven low's paper on vitamin D?

Testosterone levels, sleep, and recovery are all associated with optimal vitamin d levels.
Life and death though? We're talking about selection not just hey I get more sleep than you do.
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Old 07-15-2010, 05:40 PM   #86
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Re: Study finds correlation between C.O.G. and Speed

http://www.livescience.com/history/0...p_highway.html (WFS) only talks about 60,000 yrs ago though.
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Old 07-15-2010, 07:32 PM   #87
Jamie J. Skibicki
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Re: Study finds correlation between C.O.G. and Speed

Aush,

You are missing the point, it's not about life and death changes , its about who gets laid. THats it. If I feel a little more energy because my vitamin D level are better, I kill the deer when the guy whos level are off doesn't. If that happens on a regular basis (I perfrom a lot better when I'm taking vitamin D) then that guy may not die (I'm a nice guy and share the deer), but I"m a more desirable mate.

UV protection, same thin. If I'm sunburned or have sun posioning or whatever, it's not going to kill me, but I will perform less well and attract less mates.

ANd the differences are very slight, but compounded slight differences over time add up.
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Old 07-15-2010, 08:17 PM   #88
Katherine Derbyshire
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Re: Study finds correlation between C.O.G. and Speed

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Correct, I have no problem with race if it means nationality or community group. But race simply as skin color is where I have the problem as that is not accurate. The line gets gray (no pun intended) very quickly.
As noted, the difference is between the scientific and colloquial understandings of race. Given the history of dark-skinned people in America, the colloquial understanding of race is problematic in the extreme.

From a scientific perspective, though, it's just a word used to describe populations with similar traits. You can also talk about the red-shafted and yellow-shafted "races" within the population of Northern Flicker woodpeckers. Observing the relative prevalence of the two (and of intergrade specimens with mixed plumage) gives information about migration and breeding patterns. And it's an easier and less intrusive measure than trapping thousands of birds and taking DNA samples.

In human populations, information about skin color gives insight into origins and migration patterns, too, and can be recorded more easily than less visible genetic traits. It's a starting point, but no one is claiming that it tells you all you need to know.

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Old 07-15-2010, 08:21 PM   #89
Katherine Derbyshire
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Re: Study finds correlation between C.O.G. and Speed

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Originally Posted by Shane Skowron View Post
Ancient humans didn't have the luxury of hiding whenever it got hot. It wasn't until like 200 years ago that people did anything after dark, for safety and practical reasons. Hunting and gathering all to be done during the day.
Or at morning/evening twilight. In barren environments like deserts, moonlight and starlight can give quite adequate light for travel and the kind of tracking involved in persistence hunting.

Katherine
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Old 07-15-2010, 09:15 PM   #90
Shane Skowron
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Re: Study finds correlation between C.O.G. and Speed

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Here's the problem..there is NO tangible life or death advantage to having more or less hair...just like Vitamin D production, just like uV ray protection.
Actually, yes there is. It's why animals die during persistence hunting, because they have too much hair and they sweat at low rates. So they overheat and die.

Humans can run long distances because they have low body hair and have an effective sweat system. So they stay cool and alive.

In fact this is one of the biggest differences between humans and other mammals. You think it's just coincidence that certain populations are hairier than others when such a trait serves as the distinguishing feature of the human race? I don't. I think the people that needed this feature the most were most likely to breed and keep it.
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