Eyes

[Sarahs_guy]

Why do Japanese and Chinese people have slanted eyes? Is there any scientific reason why they have them? I'm not talking about genetics but evolution instead. Thanks for any help.

[geofbob]

I'm not so sure that Japanese and Chinese people do have slanting eyes; I've just been looking at photos of Chinese and Japanese people on the Internet, and to me their eyes look as horizontal as those of Europeans. But even if Asiatic eyes are angled, surely this is simply the sort of variation in colour and form found within all species. It's hard to imagine that there could be any environmental factor specific to Asia which encouraged the evolution of slanted eyes.

[rekstout]

On the basis that early man arose somewhere in what is now central Africa, they would have migrated NE and NW to what is now Europe and Asia. There would therefore be three geographially disparate groups which would have followed their own evolutionary paths for the last however many thousand years which results in minor physiological differences in skin colour, hair colour, eye shape and colour.

As to why narrower, more pointed eyes are a SE Aisian trait is harder to say, the eyeball is the same shape bu there is additional skin around the eye socket creating a shorter opening. One could surmise that this is because the sunnier climes in that region gave those with this trait an evolutionary advantage and thus became the dominant breeding group. Similar arguments could be made for hair colour, skin tone or eye colour.

[incitatus]

The term for this is the epicanthic fold. It doesnt appear to confer much advantage in itself, after all the sunshine argument would hold true of africa too, and the mongol races also have epicanthic folds and it aint that sunny in siberia. Probably it is a rider, that is a trait which forms as the result of another trait. An example is dalmations. The gene that makes them spotty also makes them irritable and deaf. Or quite often. As to which gene it is riding on: unknown. There are many variants between the asian and european populations: stature, length of appendix, lactose tolerance, sickle cell trait (this is largely african but some asian races get it too) that sort of thing.