While early humans’ migration led to changes in our skin tones, what affected the distinctive face characteristics of each race?
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I’ve heard it speculated that longer noses developed in colder regions because they help to warm inhaled air a little bit more.
Similar to skin tone, climate would effect face structure, foods eaten, other sapien species interbreeding, cultivation leading to people eating softer foods, all would affect face characteristics
The huge variation in human facial features is thought to have arisen so that individuals are more easily recognizable within the group.
As for the specific facial features we recognize as racial differences, that becomes more difficult to answer. First, it’s important to understand that the racial lines we draw and the facial features we associate with each group are not separated by hard lines. So having specific facial features are not necessarily characteristic of the groupings we tend to refer to as race. For example, not every person we would group as ‘asian’ would have the characteristic asian monolid.
There are some race associated facial features that may have functional evolutionary cause. Back to the monolid example, it’s thought that the monolid helped provide protection in the cold, windy climate of Mongolia. While the epicanthic fold found in African people may provide some protection against high UV light in desert climates. These are rather tentative theories though not remotely agreed upon in the scientific community.
For many facial features there are little to no functional associations and so we attribute these differences to sexual selection. So some features for some populations were just more attractive than others so it proliferated. Blue eyes and green eyes both are caused my low melanin, but there is no real functional difference that would advantage blue eyes over green eyes or vice versa.
So while some race associated facial features may have some functional evolutionary cause, most facial features likely evolved due to sexual selection within those isolated populations.
Over time, random changes happen in the DNA of any organism. These mutations can lead to different traits and they are passed to the children of the organism.
Evolutionary pressure is when one trait keeps the person alive better so they have a better chance to have children and pass on the trait.
Not all changes in facial features are because of evolutionary pressure. Some random changes just happen. Because the populations of different races were separated, the random changes that accumulated in each area would be different.
Also, perhaps, there came to be styles as there are styles in clothing or architecture. When people choose mates to have children with, perhaps they favored certain facial features over others. But this would not be necessary to explain variation between geographically separated groups.
The OP’s question comes from a faulty understanding of evolution. Not every trait is “because” that trait will “help” There’s no design and no designer. As long as the trait doesn’t cause harm, it doesn’t have to have a purpose.
The environment might cause a few certain features. Disparate peoples in with little to no contact for many years can often have similar features because of where they live. Big lungs and small bodies for people at altitude, for example.
It’s perfectly reasonable to say most of it is down to chance. Often very small groups of humans made it to a new place and they were on their own. Any genetic features they already had could be reinforced for no evolutionary reason. It’s just down to having a small starting population.
Places like India and China have different looks, despite being very close to each other. This must be down to borders and cultural reasons since the environment isn’t that different. Yes of course the become a bit more similar at the borders, but that’s just because they’re bound to meet.
ELI5 version? Random chance, combined with humans who were considered better looking having more babies, caused separate groups to change over time
I heard that the way a person talks/language can shape the face by the muscles being used, also the way a person holds their tongue in their moth, how they breath (nose or mouth breather) can all affect face shape (over the course of years or in a family’s over centuries) it is not known if the shape of your face gets recorded slightly into your DNA to now pass on to children..
Climate also played a role. The hot climate in Southeast Asia is one of the probable causes why we have short and stout nose and round (some large)bnostrils. In cold areas, people have long and slender noses with slim nostrils to conserve warm air while breathing. Well at least that’s how we were taught in history.
It’s the same as skin tones. Features which contribute to being more healthy, or being seen as more healthy, mean you are more likely to breed and pass on that trait.
I’m going to make three posts.
Post 1. Where did non-black people come from?
The non-black peoples are generally descended from a single group which left East Africa a very long time ago.
The highlands of East Africa are low malaria and are called the White Highlands because they are suitable climate for light skinned people.
Some of the light skinned people of these white highlands may have been sent out to Asia, forming the ancestors of modern non-black people. The rest of the light-skinned highlanders may have been simply assimilated so that we do not see much of them these days.
In Paraguay there is a race of pale-skinned Japanese-looking “wild men” called the Ache. These Ache appear to have been originally slaves of the brown-skinned Guarani, but the Ache fled into the forest to live as maroons free from Guarani persecution.
Perhaps the first nonblack people fled into Asia from black persecutors; perhaps however they were colonists of some sort, parting with the black people on friendly terms. Either is possible.
My source is “Ache Life History” by Kim Hill.
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