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

Before transport most people lived within a smaller distance of where they were born, meaning that the way their skin is adapted is based on survival in that environment as an average

An average of the whole years sunlight hours and intensity determines the base melanin concentration within cells (that gets passed on)

Then tanning (and it fading) takes up the peaks and troughs