Evolution of humans?

Why did some humans evolve to have blond hair or red hair? Or blue eyes or green eyes?

Is it only the amount of sunlight that does this? What other factors caused hair or eyes to change?

If it is northern Europeans that got blond or blue why did not native Americans that lived in Canada get the same way? Or Eskimos? They live in the same climate as northern Europeans?

Evolution of humans?

I've heard a few theories on this. Most things I've seen agree that the original humans were black--once we lost our fur, the intense sunlight of Africa selected strongly for dark skin.

The two theories I've heard for why Europeans lightened are either that dark skin leads to vitamin D deficiency in a lower-light environment, or simply that once the selective pressure for dark skin was gone, genetic drift moved humans back to the ancestral mammal condition of unpigmented skin. (Most mammals are pink under their fur).

I beleive that populations of Asian descent living in the far north migrated there recently enough that there hasn't been time to adapt their skin color.

Evolution of humans?

good question and good answer...but don't forget random mutations! Report It

Evolution of humans?

Sunlight did play a part in changes in eyes and hair but also just slight genetic changes couldve resulted in color changes. Native Americans were nomadic and changed their geography often they did not come from North America, they moved there so their necessary genetic changes had already taken place. Eskimos also migrated to where they live from Asia and thats probably why they have some same resemblances. Plus way up north it can be 24 hour sunlight for months. So dark hair is helpful.

Evolution of humans?

Simply put, I think it's just variation. Life evolves in variation and that's the way it keeps on going because if we were all the same then we would all have the same flaws and it would be easier to die out that way.

Good question.

Evolution of humans?

Natural selection plays a big role in evolution, as you have already pointed out (eg. people who lived in very sunny climates such as Africa had more melanin in their skin to absorb UV rays). However, there is more to evolution than just natural selection. Physical separation, such as the distance between continents, causes some alleles to be randomly lost or magnified within the populations. After hundreds or thousands of years of breeding within isolated groups, each population is different from the next.

Evolution of humans?

some humanes have blond hair because they are part of gods hummor