The evolution of dark skin is linked intrinsically to the loss of body hair in humans. By 1.2 million years ago, all people having descendants today had the same receptor protein of today’s Africans; their skin was dark, and the intense sun killed off the progeny with any lighter skin that resulted from mutational variation in the receptor protein.[3] This is significantly earlier than the speciation of Homo sapiens from Homo erectus some 250,000 years ago.
Dark skin helps protect against skin cancer that develops as a result of ultraviolet light radiation, causing mutations in the skin.[citation needed] Furthermore, dark skin prevents an essential B vitamin, folate, from being destroyed. Therefore, in the absence of modern medicine and diet, a person with dark skin in the tropics would live longer, be healthier and likelier to reproduce than a person with light skin. White Australians have some of the highest rates of skin cancer as evidence of this expectation.[4] Conversely, as dark skin prevents sunlight from penetrating the skin it hinders the production of vitamin D3. Hence when humans migrated to less sun-intensive regions in the north, low vitamin D3 levels became a problem and lighter skin colors started appearing. White people of Europe, who have low levels of melanin, naturally have an almost colorless skin pigmentation, especially when untanned. This low level of pigmentation allows the blood vessels to become visible and gives the characteristic pale pink color of white people. The loss of melanin in white people is now thought to have been caused by a mutation in just one letter out of 3.1 billion letters of DNA.[5]
It’s kinda long, but I thought it was a cool read from wikipedia (whether it’s true or not).
I can’t find the full text of that reference 3, and the abstract is not sufficient, but the claim seems highly dubious to me.
I do not see where it could be known that all individuals had such-and-such DNA in any given particular regard that far back. We don’t have intact DNA from human remains that are that old, let alone large sets of samples from all over the world.
Most likely this is based on computer projection.
An added aspect of ignorance is that it is not the case that there is only one form of melanin in man anyway. I don’t recall the number of forms but it’s at least 7 and it seems to me the number was more like 9.
(Which is why people of similar overall darkness can have different tone.)
[quote]Bill Roberts wrote:
I can’t find the full text of that reference 3, and the abstract is not sufficient, but the claim seems highly dubious to me.
I do not see where it could be known that all individuals had such-and-such DNA in any given particular regard that far back. We don’t have intact DNA from human remains that are that old, let alone large sets of samples from all over the world.
Most likely this is based on computer projection.
An added aspect of ignorance is that it is not the case that there is only one form of melanin in man anyway. I don’t recall the number of forms but it’s at least 7 and it seems to me the number was more like 9.
(Which is why people of similar overall darkness can have different tone.)
[/quote]
I’m more ignorant on this than you are, but I always thought they knew stuff like this simply from studying modern DNA. I know there’s obviously some extrapolation, but I always thought this was pretty accurate.
I agree that they must be projecting from modern DNA. I exceedingly doubt that it can be known the skin color of all people everywhere a million years ago based on that.
In particular, if they are claiming a one-nucleotide (letter) change is all that is involved, then there is no rate of drift to measure. But that is not the only problem.
I suspect the problem comes from it being an anthropology paper, not a paper by geneticists. Anthropology is not known as one of the hard (that is to say, rigorous) sciences.
That makes the assumption evolution is true. It’s not, God created the Universe some time after the domestication of Canis Lupis Familiaris and after the Sumerians invented glue. It says so in the Bible.
[quote]jCaesar88 wrote:
TheBigV wrote:
Dark skin helps protect against skin cancer…
That’s funny. As far as I know, blacks have far more incidents of skin cancer than whites or any other ethnic group. [/quote]
Actually,black people do have less incident of skin cancer than whites…BUT black people have more serious problems than whites if they do develop skin cancer.
The biggest misconception is that black people(or darker skin people in general) can’t get skin cancer.
yea im from australia im half black n half white, all my white friends get fucked up from the sun haha im not that dark but i dont burn i just get more brown , dont even need to wear sun tan cream. im gonna breed with a darker chick so my kids will survive as the whole in the ozone gets bigger n bigger n more people get fucked up
when i was in elementary school, a white friend of mine said he heard that black people were that way because of a mold in our skin. and he wouldn’t lie to me.
[quote]Judas wrote:
yea im from australia im half black n half white, all my white friends get fucked up from the sun haha im not that dark but i dont burn i just get more brown , dont even need to wear sun tan cream. im gonna breed with a darker chick so my kids will survive as the whole in the ozone gets bigger n bigger n more people get fucked up
burn cracka burn[/quote]
Well that is awesome they’ll survive the “whole (sic) in the ozone,” because they won’t be able to pass the 3rd grade.
[quote]Brother Chris wrote:
Judas wrote:
yea im from australia im half black n half white, all my white friends get fucked up from the sun haha im not that dark but i dont burn i just get more brown , dont even need to wear sun tan cream. im gonna breed with a darker chick so my kids will survive as the whole in the ozone gets bigger n bigger n more people get fucked up
burn cracka burn
Well that is awesome they’ll survive the “whole (sic) in the ozone,” because they won’t be able to pass the 3rd grade.[/quote]
