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So we all started black?



No we would be pale like a freshly shaved chimp. As we gradually lost our hair we evolved to have darker skin. When we migrated out of Africa we adapted again to mountains and caves then became pale again.

The key points are both dark and pale skin are evolutionary traits once we lost hair. If you sweat you probably want light skin under fur.


And then you have polar bears, whose main problem is staying warm rather than staying cool or avoiding sunburn. They have black skin and translucent fur so that all of the sunlight is absorbed below the outer insulation layer instead of on top of it.


Also the parts of hair cells that would normally hold pigment are hollow rather than filled with pigment because an air void conducts heat less and thus is more insulating.


I don't think we have any skin samples from back then, but yes, that is almost certainly the case.


What's started?

We had fur at one point, and our still-furred cousins have pink skin, so our ancestors probably did as well.

It's generally believed to be the case that dark skin evolved with hairlessness, and was lost by some branches of the tree during the glacial period.



Googling "shaved chimpanzee" (did something new today!) gives photos in the pink/gray range.

https://www.google.com/search?q=shaved+chimpanzee


And are our closest cousins, yes.

Here's a popular-press citation for the consensus that our furred common ancestor was pink skinned: https://www.discovermagazine.com/planet-earth/why-did-darker...


Nice. I was aware of the folate/vitamin D balance, but hadn't heard anything about sub-fur skin color.


If we go back far enough, we have ancestors without any skin at all. Boom, problem solved.


Not sure if you are joking, but that's by far the most probable option. Just look at civilizations living for millenia near equator, be it Africa, isolated islands in Indian ocean (ie Nicobar) or native Australians.

Planet was colder, and around equator you actually have quite habitable places even now, deserts are further from equator. But you get tons of light whole year in very stable pattern.




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