Eli5 why are there different races?


Why aren’t we all the same colour and have the same facial features?

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Survival of the fittest favors advantageous gene mutations for different groups of people in different places.

Different skin colors have different advantages in different environments. Closer to thr equator, the slight sun protection offered by darker skin is beneficial, so it was selected for over thousands of years. Further from the equator, people with lighter skin were better able to get adequate vitamin D from sun exposure, so that was selected for.

Some traits evolved like that. Some would be due to chance- isolate a bunch of populations and each of those populations would have a slightly different genetic makeup, so some traits would become much more common. Add to that random mutations that occur in one population or another that then stick around, etc, and you’ve got a wide variety of traits present in different regions.

Because our ancestors lived in different parts of the the world.


That’s a map of the different skin colors, they get darker down the equator which is where the hottest climate is. As it happens darker skin also has better protection against the sun

Dark skinned people didn’t get enough vitamin D when they migrated to less sunny climates, so those with lighter skin were more likely to survive and have children. Other differences have similar explanations, like brown eyes being better at seeing in bright light but blue eyes being better in the dark.

In some cases it’s just random chance, things are bound to diverge when you’ve been apart for long enough. I doubt most of the differences in facial features (nose shape, etc) would have much of an effect on anything, except for the epicanthic folds Asian people have on their eyes.