eli5: If more melanin is advantageous in warm climates, why is less of it advantageous in colder climates? Wouldn’t darker skin still be most advantageous in cold climates where it might occasionally be hot?
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Humans need vitamins, basically. The more complex answer is, Humans synthesize Vitamin D using the ultraviolet radiation in sunlight, and melanin blocks that to help avoid skin cancers, because too much is also bad for you.
The advantages of melanin have nothing to do with heat and everything to do with UV exposure, it just so happens that places with more intense UV exposure also generally tend to be warmer (but not always).
Melanin protects the DNA in your skin cells from being damaged by UV light, that’s why people who evolved in sunny climates tend to have darker skin. The main disadvantage to having high melanin levels in climates with lower UV exposure is that it tends to lead to vitamin D deficiency as natural vitamin D production in the body is stimulated by UV exposure.
Melanin required resources to produce, and also does sloghtly reduce vitamin D production so in areas with less light, it was better to have less melanin and maximize vitamin D production. At higher latitudes, UV damage isn’t as much of a worry.
BUT this particular hypothesis on why skin color changes around the world is not definitive despite how popular the idea is. There are likely other interacting factors we haven’t worked out yet.
Melanin required resources to produce, and also does sloghtly reduce vitamin D production so in areas with less light, it was better to have less melanin and maximize vitamin D production. At higher latitudes, UV damage isn’t as much of a worry.
BUT this particular hypothesis on why skin color changes around the world is not definitive despite how popular the idea is. There are likely other interacting factors we haven’t worked out yet.
I live in south Texas but I was born in wa and grew up in wi. I just hate the sin in general. nut also I the far north they do have darker skin to prevent against uv damage from the sun shining odd the snow. light skin us a kinda inbetween places kj d of thi g and is actually not that helpful. more prone to sunburns, and skin cancer.
Melanin is better for climates with more sunlight, it’s not about temperature. There’s places with alot of sunlight that are cold and the people still have more melanin. Having melanin isn’t as important in places with less or milder sun light so it’s not produced as much
I live in south Texas but I was born in wa and grew up in wi. I just hate the sin in general. nut also I the far north they do have darker skin to prevent against uv damage from the sun shining odd the snow. light skin us a kinda inbetween places kj d of thi g and is actually not that helpful. more prone to sunburns, and skin cancer.
Melanin is better for climates with more sunlight, it’s not about temperature. There’s places with alot of sunlight that are cold and the people still have more melanin. Having melanin isn’t as important in places with less or milder sun light so it’s not produced as much
I live in south Texas but I was born in wa and grew up in wi. I just hate the sin in general. nut also I the far north they do have darker skin to prevent against uv damage from the sun shining odd the snow. light skin us a kinda inbetween places kj d of thi g and is actually not that helpful. more prone to sunburns, and skin cancer.
Melanin is better for climates with more sunlight, it’s not about temperature. There’s places with alot of sunlight that are cold and the people still have more melanin. Having melanin isn’t as important in places with less or milder sun light so it’s not produced as much
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