How long until I turn black?

[CplFerro]

If the different races of man evolved in response to different climates, how long would it take a population of white people transplanted to an uninhabitated zone of Africa to turn black? The same question goes for blacks transplanted to northern Europe.

[Ziggurat]

If the different races of man evolved in response to different climates, how long would it take a population of white people transplanted to an uninhabitated zone of Africa to turn black? The same question goes for blacks transplanted to northern Europe.

That would depend very much on what sort of behavioral adaptations they adopted to deal with the change. Nowdays, for example, people can (and would) get vitamin D supplements to prevent rickets.

So basically, unless said group was thrown into primitive conditions as well, it might not happen at all, because the selective pressures don't really exist anymore. Remember, too, that it doesn't matter if you die from skin cancer at 60 rather than living to 90 if you've already had children.

Assuming you did throw them into primitive conditions as well, I don't really know, but a wild guess based on nothing more than a hunch would be in the tens of thousands of years.

[drkitten]

Assuming you did throw them into primitive conditions as well, I don't really know, but a wild guess based on nothing more than a hunch would be in the tens of thousands of years.

Unless nature or science found another path that didn't involve skin coloration changes. My understanding is that one of the primary reasons for dark skin is to protect against sunburn.

Here's a radical idea. Wear clothes!

Here's another one. Work at night!

[godless dave]

I'm going to guess less than 200,000 years.

[Soapy Sam]

Back in the Apartheid days, I described an Afrikaaner as "swarthy" to his face. He was a seriously unpleasant piece of trash. I told him he was evolving to adapt to African UV levels and his great grandkids would be black.
He went quite pale.

[LarianLeQuella]

LOL Soapy Sam. I'm sure that got you lots of friends, but must have been worth it for the reaction!

[El_Spectre]

If the different races of man evolved in response to different climates, how long would it take a population of white people transplanted to an uninhabitated zone of Africa to turn black? The same question goes for blacks transplanted to northern Europe.

I'm pretty sure it doesn't work that way... while it would be an advantage to be darker in equatorial regions, it doesn't mean those mutations will happen.

In a related note (I can't remember the source), I recently read that it took a surprisingly short time - something like 15,000 years - for humans to go from very dark Africans to very light proto-Scandanavians. How much of that is selection based, and how much is migration, I don't know.

[shadron]

I'm going to guess less than 200,000 years.

Pretty safe :) . Homo Sapiens seems to have moved from medium brown (Bushman complexion) to lily white (Scandinavian) on the order of, perhaps, 20,000 years, and I'd say, given the right pressures, it could be done in 10,000, perhaps less. That's roughly 4-500 generations.

Before the domestication of animals, human lactose intolerance grew rapidly in childhood as the lactase producing gene was shut down. Once domestication of animals started perhaps 4000 years ago, the gene controlling that shutdown process has mutated to the point that 30% of all humans experience no lactose intolerance. Furthermore, the pattern is that those cultures which are more dependent for calories from milk are the ones who more likely see the genetic change, up to 90% in herding cultures in Africa and Asia. That is one example of the possible rate of change brought on in man by the proper environmental conditions.

[CplFerro]

Answered own question.

[I Ratant]

The peoples living in the far North maintain their darker complexions relative to the lighter complected Scandanavians living closer to the equator despite the diminished exposure to sunlight by consuming Vitamin D containing foods, like blubber.

[Puppycow]

Remember, too, that it doesn't matter if you die from skin cancer at 60 rather than living to 90 if you've already had children.

Nitpick: For human beings (and some other animals), the longer you can stay alive, even after you finish having children, the longer you can continue to help your descendants to also survive and reproduce.

This is (one reason) why people don't instantly die when their reproductive lives end.

[Ziggurat]

Nitpick: For human beings (and some other animals), the longer you can stay alive, even after you finish having children, the longer you can continue to help your descendants to also survive and reproduce.

If you're not living in primitive circumstances, that's no longer an important factor in human reproduction. If you are, well, 60 is plenty old enough to have done that anyways, and you'll likely die by then of other causes.

[Roboramma]

I've seen it suggested that human skin colour differences are due to sexual selection, rather than simply selective pressures due to vitamin D or sun exposure.

If that's the case, you wouldn't expect any particular effect at all.

[I Ratant]

There may be something to that... Many white gals barbecue themselves to a nice 100 grit sandpaper skin by the age of 30, while their Latin and African contemporaries keep that soft, smooth, cool, ......... ahh.... skin for many years after that!
I prefer the natural tans, over the induced kind.

[JWideman]

I don't think the different races of man are a result of natural selection so much as heredity. What selects for Asian features? And what about all the white people in the middle of Asia?

[godless dave]

I don't think the different races of man are a result of natural selection so much as heredity.

Huh? No one is disputing that skin color is a hereditary trait.