I realised that for some reason, I still don’t know this. Why do we have different skin colors, hair textures, eyes or such? Is it just a random thing that happened or are there evolutionary reasons to it?
I realised that for some reason, I still don’t know this. Why do we have different skin colors, hair textures, eyes or such? Is it just a random thing that happened or are there evolutionary reasons to it?
Without the evolutionary pressure to maintain high melanin levels in the skin, and possibly also from interbreeding with Neanderthaal, European people’s got paler.
Someone mutated to have eyes that were paler and more sensitive to light, which was useful during the longer nights further north, and that mutation spread.
So it’s a bit of both.
Put differently (so as not to imply high melanin is fundamentally superior):
Someone mutated to have lower melanin levels in their skin, which was useful to absorb more sunlight for Vitamin D production further north, and that mutation spread.
But what’s the evolutionary pressure keeping melanin levels among ethnicities that stayed black? And why does it affect people in Central and South Africa but not in North Africa and the Middle East, when both regions are about equally hot?
It’s important to think about the time scale that evolution works on. These changes happened very slowly 50,000+ years ago.
The regions near the equator where people still tend to be lighter skinned have been in contact with and interbreeding with lighter skinned people for thousands of years, plus many migrations and invasions.over the past 10,000 years.
Most likely a conbination of the amount of sun exposure and other poaitive genetic mutations that happened alongside melanin levels.
An example of the complexity of genetic changes being intertwined is resistance to malaria and sickle cell anemia. The benefits of resistance to sickle cell anemia outweigh the negstives of the increased chance of sickle cell anemia so the mutation has persisted.
It is likely that North African populations had something that was beneficial as a tradeoff for their comparably lighter skin. Wearing clothing that covers a lot more of their body and having shelters from the sun could also help to mitigate some of the sun damage.
So it is complicated and most differences are due to a combination of genetic traits, they don’t get passed down one trait at a time.