Why do darker skinned people live nearer to the equator?

14 February 2010

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Question

If black absorbs light and white reflects it, why do darker skinned people live nearer to the equator and lighter skinned people further away?

Answer

Well; mankind first originated and evolved in Africa - what's probably now Northeast Africa is where the first modern humans originated from. It's equatorial; it's very hot; there's huge amounts of sunlight. So the risk there is that people will end up with ultraviolet radiation penetrating their bodies.

Now, the first thing people think of when you say "ultraviolet" is skin cancer. But, actually, skin cancer isn't the sole explanation for why people have black skin. Most people don't get skin cancer until after the age at which they would have reproduced anyway and therefore it wouldn't really have any evolutionary benefit to them to have black skin.

In fact, why they black skin is to prevent ultraviolet radiation breaking down the chemical folate in the skin. Folate is really important for the production of DNA. In order to conserve their reserves of folate, people who were at first evolving in Africa actually evolved to have black skin. The common ancestor that we share going back in time with, say, chimpanzees about 6 million years ago, those animals all had pink skins but they have fur to protect them. As soon as they became hairless, our early ancestors had to evolve dark skin to protect them from the sun.

But when they migrated north, out of Africa, and they ended up in high latitudes, like in Britain, where sunlight is something we don't see very often, there was just not enough sunlight - especially coupled with dark skin - to produce enough Vitamin D which gets made in your skin, so people then became a bit Vitamin D deficient. So we lost the genes that made us have black skin in order to produce more Vitamin D. The benefit of doing that is that you have stronger bones. The down side is you're slightly more vulnerable to the ultraviolet in the sunlight, but as there's much less sunlight it was a worthwhile gamble to take.

Comments

This is such lies! Stop telling ppl they evolved from monkeys! That’s not how evolution works! Every living plant and animal works WITH the earth. Nature would never keep the very thing that it evolved from. The point of evolution is to upgrade &!harmonize with the planet! Why would humans evolve from apes and apes still be here????? Even Darwin on his death bed didn’t believe his own bullshzt. Furthermore it’s kind of racist because scientist know that we all came from Africa and want to tell us that our African ancestors evolved from apes! Not true! If anything caucasians are the most recent man it would be highly likely that they did! They share the common trait of pink skin and silky straight hair like the apes you claim

Because the tripe you have written above is just misinformed, reactive rubbish that is totally irrelevant to the content and explanation above.

The answer supplied is correct and accurate. Your contribution is not.

Maybe engage brain - and eyes - before firing off salvoes of crap in the comments section in future?

Interesting

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