Replies to This Discussion

Permalink Reply by Bharat on January 5, 2012 at 5:24pm

Just curious question for american friends... I tend to believe that (without any scientific facts), African-Americans living in America now have lighter skin colour than their ancestors from hundred or two hundred years back?
Am I right or wrong?
I Apologise for asking this question in this discussion.
Thanks.

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Permalink Reply by Colleen on January 5, 2012 at 6:09pm

Hi Bharat, I haven't read anything suggesting this change, but I don't see it outside of the realm of possibility.  Our genes are not "blue prints."  Their expression is set up to respond to our environments, permitting us to adapt.  However, as I mentioned above, the sun is not the only way to access the vitamin D3 and the B vitamin folate.  Given the right diet, a change in skin color would not be a necessary adaptation.  If any such change existed, I would not consider it permanent or relevant.  Side note: please remember that not all people with dark skin in America have an African ancestor from the last 100 to 200 years.  Americans with African roots would not adapt any differently than other groups with warm-climate ancestors simply because their great-grandfather once lived in Africa.

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Permalink Reply by Bharat on January 5, 2012 at 6:35pm

Thank you very much for the clarification Colleen!

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Permalink Reply by Danny Sanchez on January 5, 2012 at 6:50pm

I like the book "Guns, Germs, and Steel" by Jared Diamond

One of my favorite books of all time and it does a really good job of explaining how the different races of the world developed into the way they are now.

Its really more about civilizations and societies but its got some stuff on evolution too.

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Permalink Reply by Reg The Fronkey Farmer on January 5, 2012 at 7:38pm

Hi Bharat - 200 years is nowhere near enough time to make any difference. Maybe 200 generations might start to be the beginnings of any noticeable change.

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Permalink Reply by Artor on January 5, 2012 at 8:41pm

Although, you have to winder how many families who have been here for 200 yrs might still be pure-blooded Senegalese, or whatever. Dilution of a trait will change it much faster, as well as environmental adaptation.

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Permalink Reply by Rob Klaers on January 5, 2012 at 9:47pm

Reg.. Even in 200 years,you have about 8 generations, assuming that each generation is 25 years. Some are finding that particular traits change faster than others. This is in respect to how quickly some adaptation would need to be done in respect to environmental changes.

In relation to Bharat;s question..Approaching it from a more Anthropological direction,  I would say it's more hereditary then an evolutionary thing. What I mean by that is if African-Americans are lighter in color than their Ancestors or even their modern day  counter-parts in Africa it would be more along the lines of there being Caucasian (ie, Northern European) in their background several (4-5 at minimum) generations back. Whether this was due to in relation to master-slave relationships or two people of different colors making that 'love connection' or whatever. You will find that is the reason the color difference more so then evolution. Though I wouldn't be surprised if there is some evolution sneaking in there a little as a result of that exposure and adaptation to the milder climate here in the U.S.  

That's just my thought..

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Permalink Reply by Bharat on January 6, 2012 at 3:20am

Thank you for your thoughts on this. May be 200 years not enough to make any significant change in their DNA coding, but as Colleen points out, may be due to diet change, there may be slight change in skin color. 

Evolution is fascinating subject! All mighty DNA is responsible for everything.. :-)

Going back to the main discussion topic, Kari you can ask your mother simple question like, why whenever we are walking or running, we move our hands back and forth... 

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Permalink Reply by Ron V on January 5, 2012 at 9:11pm

These observations are a product of evolution.  If your mother is not scientifically inclined, however, as my mother is (and adheres faithfully to the Bible), you have little chance of explaining this to her so she can understand or accept it.

But, if you really want to research/understand this, I recommend:

The 10,000 Year Explosion (Cochran and Harpending).

http://humanorigins.si.edu/evidence/genetics/skin-color

http://en.wikipedia.org/wiki/Human_skin_color

http://www.bgsu.edu/departments/chem/faculty/leontis/chem447/PDF_fi...

Good luck!

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Permalink Reply by Craig Nomazlab on January 6, 2012 at 10:02am

Evolution didn't stop as soon as we started to resemble humans. They evolved to adapt to the environment they were living in and the environment in Asia is quite different from that in Africa which is quite different from that in Europe, etc.

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Permalink Reply by Steve on January 6, 2012 at 10:40am

There are indications that people living on the Tibetan Plateau underwent evolutionary changes in as little as 3000 years. Instead of producing more red blood cells to cope with the lack of oxygen at altitude like other people, they somehow handle the existing oxygen better

http://www.livescience.com/6663-tibetans-underwent-fastest-evolutio...

http://www.livescience.com/6543-revealed-tibetans-survive-thin-air....

Even then, the article cites lactose intolerance as taking 7,500 years. So it doesn't even take millions of years.

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Permalink Reply by Kir Komrik on January 6, 2012 at 11:14am

Hey Steve,

 

This wouldn't surprise me based on what I've heard/read. I can't remember the source, but isn't there some indication (biologists help me out here) that the TOE and natural selection are much more episodic than originally thought? I seem to remember reading that somewhere. Anyway, the consensus was supposedly developing around the idea that many of the changes we see in species occured through (additional?) rapid processes that might yet be unknown to us. Anyone hear this? Thanks,

 

- kk

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