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

Melanin is useful for blocking against large amounts of UV radiation. It lowers chances of skin cancer from running around in the sun constantly.

But you need to take in *some* UV light to get vitamin D. If you live in someplace cold, you don’t go out much if you like having all of your limbs. That means you don’t get much sunlight, so you need to take in as much UV as you can so you can get your vitamin D.

TLDR:

Light Skin = All the Vitamin D. Good for minimal sunlight

Dark Skin = None of the Skin Cancer. Good for lots of sunlight