If East Asians Developed Epicanthic Folds To Adapt To Snow Blindness, Then Why Didn’t Northern Europeans Develop The Same Trait?

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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.

In: 973

It wasn’t so much about the snow but more about the wind. That’s why some indigenous Australian tribes have it as well.

Different traits randomly appear in any given population, and stay if they help the population survive in that particular environment. (That only beneficial or neutral traits survive, no matter how convulated or non-intuitive, make the random traits that do survive erroneously seem, to a casual observer, like an intelligent designer) This particular trait probably never appeared in Northern Europeans, and/or they had/have another trait that compensates.

>I was wondering why Northern Europeans, specifically Germanic and Nordic people that lived in the colder regions of Northern Europe,

You mean like the Sami? Northern Europeans with epicanthic folds.

Two things here.

Firstly, we don’t actually know why epicanthal folds developed, everything right now is just possibilities with various degrees of plausibility.

Second, evolution isn’t inevitable. There’s no list of optimal traits for an environment that it goes down and makes happen. How evolution actually works is that sometimes mutations occur, and sometimes those mutations happen to be beneficial, so creatures with that mutation are better at reproducing, so that mutation becomes more common in the population gene pool over time.

Epicanthal folds only arise if a mutation that causes them occurs, and that feature happens to be advantageous in some way (which could be for any number of reasons, including potential mates just finding them attractive – they don’t necessarily need to have a function). If epicanthal folds are of benefit in bright terrain, then Europeans didn’t evolve them because the mutation that causes them simply never happened. If it had, it would have been selected for, but it didn’t.

Evolution takes random paths that may or may not lead to useful features. We have the power of hindsight to guess which conditions might have led to a feature, but there is not telling which features will appear. Your question can be generalized to why don’t all animals fly or why don’t all animals run very fast. It may be the case that no others had the mutations that led to folds or some had mutations but that did not give them enough survival fitness to propogate their genes

Evolution won’t do the same thing necessary in the same condition in 2 separate events/times etc.

You mean like … the Sami people?

Check out any old pictures of the Sami before they interbred with other Europeans, and you will see that they developped the same epicanthal folds as Asians, as an adaptation to cold.

Most Europeans you see today evolved in more Southern latitudes

I’m Finnish and have epicanthic folds. Turns out they’re relatively common here, and have even been used as an argument for our subhumanity in eugenics. Nobody else in my family has them.

Just an observation, definitely not an ELI5 answer, but pointing out that this isn’t unheard of.

I’m no scientist but maybe because northern Europeans had a protruded brow from Neanderthal ancestors that helped against that?

Because evolution is a random mutation that becomes prominent due to environment & survival needs

There’s no why it came to be, just why it became a common trait

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.
https://www.reddit.com/r/genetics/comments/6xklgp/white_people_with_asian_features/dmh05ve/

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.