system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do Asians have such a unique eye shape?

I can pretty much grasp how and why skin color and hair color managed to change in the way it did over tens of thousands of years of evolution but I don't understand the evolutionary need for the eye shape of Asians and why it is specific to them.
gpt
The shape is caused by the epicanthic fold, which is a fold over the inside corner of the eye. Asians aren't the only ones to have it, though, it's not unheard of among Europeans, especially the Irish and Scottish. Some Amerind tribes have them, too.

The theory is that it helped prevent snow blindness or radiation, but there's still scientific disagreement on the matter.