I’ve read that East Asians developed slanted eyes or Epicanthic Folds as a way to adapt to snow blindness in the more snowy and colder regions of Asia, and I was wondering why Northern Europeans, specifically Germanic and Nordic people that lived in the colder regions of Northern Europe, didn’t develop the same genetic trait or at least something similar to it.
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I work with a Ukrainian woman who has them. Wikipedia also says that some East and North Africans do.
Some Polish people have them, surprisingly. Where did you read about it being an adaptation? How would it prevent snow blindness (head scratching)?
My youngest son has epicanthic folds and no one else in our family does. I’m white (Italian, Irish, and German descent) and my husband is 100% Sindhi. My MIL kept implying I was cheating on my husband because of our son’s eyes. 🙄
It’s possible that this one trait was just lucky to become dominant in east Asia (with a small locus of dominance in parts of Scandinavia) and originated in Africa.
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byu/custydash from discussion
ingenetics
Iirc epicanthic folds are the ancestral trait in humans. Nobody gained them: some of us lost them. And the latter group includes most anthropologists.
I heard is also helps with dust storms.
I’d argue 4 Months snow blind + 8 months Not snow blind is conducive to non epicanthic folds.
But 4 Months winter + ongoing summer dust storms is very conducive.
Asking this question is like asking why a dice roll ended up at a 5 and not as a 6. Evaluation is random in that what traits happen vs what ones don’t is truly random. Of those random traits some of them will work, and therefore stick around and others won’t.
We don’t know for sure that East Asians developed slanted eyes or Epicanthic Folds as a way to adapt to snow blindness, but for the moment lets just assume that’s true. East Asians developed this trait, found it made them better able to see in the snow, and therefore were better able to survive. Since more of the people with this trait were surviving, eventually everyone who was alive had this trait.
Even though Europeans faced the same problem, they don’t chose to evolve based on the problems that they face. Rather we evolve and those evaluations either work and solve a problem making us more likely to survive, or they do not. You’re basically thinking of things backwards, you think it goes problem>solution but in reality it goes solution first.
Epicanthic Folds exist in populations in southern Africa, Europe and Asia. These places have very different climates. The current theories lean toward this being due to sexual selection because there does not appear to be any direct benefit of one eye type over another.
Some Nordic people have epicanthic folds especially when they are young and especially on the outer part of the eye. Also khoi and San people from Africa have them. Cold weather is not necessarily the the reason.
Finer points of evolution aside, Europe has relatively mild weather and was heavily forested, so snow blindness wouldn’t really be an issue the way it would be in Mongolia. There’s also always been a lot of intermixing throughout the continent, so you wouldn’t expect to find a lot of unique traits in the north vs. south. For unique evolutionary traits to develop you need some kind of isolation from other populations. The Ural mountains and the Sahara are two of the biggest continental barriers which explains why people on either side of each look so different from one another.
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