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?

Question

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?

In: 1641

Answer 1

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.