Anthropologists have debated how long ago the ancestors of modern Native Americans came to the western hemisphere. One school holds that it was comparitively recent- about 10,000 years ago. Others claim that it was longer ago, perhaps much longer.
It seems to me that there’s an argument against Native Americans having been around for a long time. In the Old World you have black skinned Africans, Austrailians, Adaman Islanders, various peoples in southern India, Indonesia, the Phillipines, etc. Presumably these people have lived near the equator long enough to have evolved black skins. But as far as I know, none of the tribes living in Central or South American have black skin; brick-red or yellow-brown but not coal black. Wouldn’t this suggest that they haven’t been living near the Equator for that long?
That’s the assumption I’ve always made. Same goes for brown skinned Inuits and Aleuits. If they had been in the Arctic as long as the Fins or Scandenavians, I imagine they’d have lighter skin. The fact that there is a lot less difference between an Eskimo and a Mayan, than there is between, say, a German and a Hutu, speaks volumes about how long their ancestors have lived at a particular laditude.
Disclaimer: If skin shade has nothing to do with latitude, then I’m talking out my ass. I’m an historian, damn it, not an anthropologist!
This business about skin color not changing to match the color/latitude/climate I learned in high school has been bothering me, too, Lumpy. I think Ursa Major has put a word in on this topic before as well.
And it is annoying.
I don’t think Darwin said you ever get what you needed to make your life better. You get what you get. If a trait isn’t valuable at the right time and place, it just doesn’t happen.
He also said that characteristics like skin color, eye color (and pattern) and hair color are likey to be subjected to strong sexual selection and this was (sexual selection) a major factor in the ethnic differentiation of humans. So looks might out weigh usefullness.
We are supposed to have tremendous variety in our genes. In any group of people there should be some darker and lighter or at least with genetic variability (even if it doesn’t show on the skin, eyes, hair of the living person in question) to have lighter or darker offspring.
I think the American Indians or natives would have had to notice that some of the offspring were darker and decided that darker was more handsome - sexual selection in other words - and the darker individuals would have more opportunity to produce more and more offspring. After several (what? hundred?) generations the population would be darker.
If the natives were happy with their hair, skin and eye colors they would just continue to mate at random and everything would probably stay the same.
It could be that the genes for darker hair, skin, and eyes were simply lost over years and years of travelling over there in Asia before they came to the Americas.
But I think I’d vote for sexual selection liking things just the way they were.
Are you driving with your eyes open or are you using The Force? - A. Foley
There is another aspect of the situation from a genetics/evolutionary perspective.
It is possible that the particular genetic elements that produce the skin color we call black simply did not make it to the Americas. The other groups that we deem black are not simply widely scattered people near the Equator; they are people for whom a direct path of migration can be constructed from a single point to their current (or pre-colonial) locations.
If black skin color is the earliest variation, the people who display it now may have simply never lost it. Each of the groups named in the OP could have reached their current locations in a fairly rapid migration during the period when all humans had black skin. People farther from the Equator could have lost that tint through various mutations. When the people bearing no genes-for-black-skin later migrated to the Americas, those who settled near the Equator developed much darker skin, but never re-acquired a now lost gene for the particular hue we call black.
An interesting idea, along with the sexual selection argument. However, in rebuttal:
Human skin color is determined mainly by how much melanin people have in their skins. Melanin is found naturally in the body as a byproduct of certain biochemical processes. So if Native Americans had been in the New World for, say, 50,000 years, it seems unlikely to me that in all that time there wouldn’t have been a spontaneous mutation for darker skin. It’s not like having to evolve wings or some such.
(P.S. the idea that light-skinned races have lost some irretrievable trait of blackness sounds comically like the Black Muslim mythology. ;))
While acknowledging the power of sexual selection, not dying of skin cancer seems like a major factor in how many descendants you leave.
My posts here are SWAGs because I truly do not know the actual genetics that are involved.
That said:
Except that color is generally regarded as having three separate characteristics. While melanin certainly has a direct affect on lightness and, perhaps, on saturation, does melanin have any direct bearing on hue? When we say that South American natives are not “black,” are we saying that they do not attain the same levels of melanin? Or are we saying that their skin looks different than “black” because of a reddish or brownish tint? Certainly, there are people from Africa whose skin is clearly “black,” in some cases having an almost bluish sheen to it. Among the “Austrailians, Adaman Islanders, various peoples in southern India, Indonesia, [and] the Phillipines” are we describing the same lightness or the same hue? I am not aware of any among this second large group of people who have the same blue-black hue that I have seen among some Africans.
If, indeed, the “black” skinned people have the same degree of lightness and the same amount of melanin as Africans while the South Americans do not, then I am way out of my element and will retire from the discussion. If, however, we have simply identified a hue (or closely related hues) that are shared among the different people that are outside the Americas and the actual lightness of the skin color (and the levels of melanin) in all the groups outside Africa are in the same basic ranges of variability, then I think my WAG should be considered.
Absolutely true–provided one accepts that skin color has anything to do with anything other than skin cancer and vitamin D. (Of course, I’d be curious as to how eager Louie would be to extend the hand of brotherhood to a successful Christian Indian or Philipino.)