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

Aside from the UV-protection a darker skin does absorb more heat, but it also radiates more heat.

So all the heat a dark skin would absorb in a cold environment would be lost equally fast, so skin colour doesn‘t matter in terms of temperature