Nature, Nova…some show on PBS…recently aired a show devoted entirely to skin. Within the past couple of weeks. (Though I can’t, for the life of me, figure out which show it was on pbs.org) Somewhere in the various sounbytes was a map of the world in skin tone. The relationship between melanin and proximity to the equator is quite apparent, and it was quite cool to look at the world from that perspective.
Why on earth should ANY social policy be based on race? You’re quite putting the cart before the horse here. To say that race exists is not to say that the difference between the races is important, only that it’s perceptible. And to say that distinct populations exist is not to say that every member of each race is easily distinguishable from each member of every other race – populations have extremes, and extremes can overlap, especially in closely related populations.
Finally, there’s no earthly reason to expect epicanthic folds to confer, or to have ever conferred, any survival advantage. Sometimes traits pop up in a population, and they do no harm, so they never go away. Perhaps the entire population of East Asia is descended from a handful of people who thought that epicanthic folds were really sexy. Or not.
Tom: “it should be noted that the African Khoi-San–living in deserts and sub-tropical climates–also have epicanthic folds”
You beat me to it. The British geneticist, Spencer Wells, has gone so far as to say that the epicanthic fold might be the ORIGINAL condition, and that it was lost in the other African and non-Asian populations. The Khoi San appear to have retained some of the oldest genetic markers found in living peoples today. A lot of speculation, but an interesting idea nonetheless.
I recently came across a statement (no cite - can’t remember the source) that some scientists believe that, based on genetic differences, there are some 8-10 different population groups (“races”) in black Africa, and everyone else can be lumped into a “miscellaneous other” group, as the genetic differences between, say, Asians and Caucasians are minor compared to differences between different African populations.
Based on my understanding of evolutionary processes and human migration patterns from Africa, this would make sense. Many African genetic differences may never have been included in the original migrations (i.e. southern populations would be less likely to migrate out of Africa than northen groups).
I would call that a pretty big survival advantage, but I don’t know much about nutrition. Do blacks in Northern Europe still suffer from lack of sunlight (and whites with their problems near the equator), or has modern nutrition/diet eliminated that problem for the most part. Put another way, if we could ensure that humans from the dawn of homo sapiens had enough D3 & folic acid, then there’d only one “race” – at least as far as skin color is concerned?
That’s an interesting question. I’m not sure what all the constrictions are, that is, my reading tells me that the subject is still in debate because it is so hard to work out. But given the required nutrients - whatever they are - are there other factors not nutrient-dependent?
Possibly. Melanin does protect against skin cancer. The page given by t-keela also has this to say:
There’s no good reason to assume that humans living over as huge a range of environments as we do would keep the same coloring. Other animals certainly vary from one area to another. Skin color might have turned out to have some preference for bonding and mating as well.
Hard to say, since it would create so many changes from what did happen. But, good question.
I don’t think melanin content has anything to do with chances of frostbite.
Perhaps caucasians developed more capilleries or greater fat distribution from developing in cold Europe?