Quote:
Originally Posted by eschaton
While people of any background can suntan (well, except for gingers) with enough exposure, most differences in skin color come down to genetics. An easy way to see this is to look at Native Americans. When they migrated into the Americas from Siberia, many of the genes for very dark skin had already been purged from their gene pool - presumably because it wasn't adaptive so far north. Once they were purged, they couldn't easily re-evolve dark skin again. This makes sense, because its easier to break a gene for generating melanin through random mutation than it is for random mutation to fix it again. Regardless, there is not a tremendous difference in skin color between Native Americans who live in northern Canada and by the equator, despite the latter group getting just as much solar radiation as Africans.
So, the Yemeni you posted has black skin because he has different genes for pigmentation than most Middle Easterners. Similarly, really dark skinned Southeast Asians exist because before the expansion of agriculture from southern China, everyone in Southeast Asia pretty much looked "black."
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Not necessarily, my skin goes from pale flesh coloured that's the norm most of the time, to the usual summer tan, to one shade off proper chocolate brown if I don't do any protection (I only discovered this when I lived in Egypt during its summer 20 years ago and came back to find myself darker than my Bangladeshi mate), and is always something my workmates find ker-azee that I can change so much. With my cap on that year I occasionally got mistaken for Black, but as you mentioned this is probably because of my genes from a tropical part of China, complete with jungles, tribes, elephants and coral reefs. I'm basically from the same place as the dark skinned dude on the boat, a sea gipsy. However that was the last year before I started to burn under the sun - never had an issue before - probably after prolonged exposure to colder climes and diet.
this my 'normal' summer tan, which usually comes on very fast after a few days and is what I reckon is my natural skin tone: khaki. In the past it could get waaay darker.
But now I have increasingly pale skin, not far off my Polish friend, and have started to get sun sensitivity and damage to boot (freckles and moles on the side of my face), As of 2011 I started to get bright pink sunburn and peeling skin if straying in the sun too long, had no idea it could be so painful and itchy.
The native Americans are different in skin tone, from the white of the Inuit (although they tan from the ice glare) to the red/ auburn tones further south. Even on the same latitude - cross from say Yakutia in northern Siberia/ Inuits in the Arctic to Chukotka or the Athapascans next door, and skin tone can be just as varied.
traditionaly pale Inuits and dark skinned Athapaskan
pale Yakuts and darker Chukots
https://www.quora.com/Who-are-Yakuts,
http://siberiantimes.com
Basically some people are genetically darker as you mention, and some people who live in sunny places and are thought of as naturally dark can be just a 'tan' - though one can argue vice versa. Then there are those who I reckon develop sun sensitivity, 'genetically' changing after prolonged exposure to a changed climate and diet, like me I reckon. And there's sexual selection - with those who favoured lighter skinned people to have kids with, traditionally a sign both in the southern (such as the 'red' and 'yellow' women of African beauty lore well before conact with the West) and in the northern societies (the 'English rose' or 'porcelain beauty' within Europe/ Asia) of people who don't have to work the fields all day, becoming a sign of class and thus beauty ideal (though that's been upturned since the 1950s as a 'healthy' tan indicated you were rich and could afford to fly off on holidays, and nowadays are an outdoorsy, sociable, sporty health guru whose mixed race kids will be assumed as 'beautiful' and have stronger DNA). It's a mix of all of them. They think the original Africans had the same reddish skin tones, as seen in their closest DNA relatives, the San/ Bushmen.
Aztecs
www.mexicolore.co.uk
San Bushmen (the closest fit to prehistoric Homo Sapiens DNA - a mix of all races, and our original template. Even though they live under the desert sun as one of the last remaining hunter-gatherer societies, their skin often does not go as dark as their African Namibian counterparts)
https://www.pinterest.co.uk/pin/129830401734102076/
compared to other parts of Africa, who like the rest of the world, diversified into what we call the major races today. Alot of people misconstrue the idea that when we came from Africa we looked like how Africans look today, and that they're our original ancestors.
https://face2faceafrica.com/article/...er-skin-colour
All they can agree on is that it seems our skin tones diversified around the start of farming (and restriction of diet and intake of vitamin D, plus stronger sexual selection), not on our contact with varying sun levels - where dark skinned people lived in cold climates for tens of thousands of years previously.