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It had traditionally been assumed that the Caucasian, or White, race developed fair skin, flaxen hair and bright eyes as adaptations against the low-light areas of Pleistocene Europe.

However, recent evidence has found that these characteristics were actually accidental mutations that activated after the last ice age ended, which meant that Cro-Magnon man, at the height of the ice age, may have been as dark as their brethren back in Africa.

Where did these mutations come from? Why did they activate in the time that they did and not sooner? And without these mutations, would the seven billion people currently living on Earth be uniformly black-skinned?

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closed as too broad by Aify, o.m., bilbo_pingouin, Hohmannfan, Separatrix Jul 12 '16 at 9:29

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ You seem to be a bit confused about the concept of genetic mutation, and evolution. Mutations appear all the time, now, before, and after. Most of them are simply discarded by the organisms. Some affect the given organism. Now evolution says that at some point, people with a given trait were favoured (meaning died less) than those without it. Now, your question could be about the evolution's criteria which explain why that selection took place at that time and no sooner. If that's the case, consider editing your question. And your last question is way too broad... $\endgroup$ – bilbo_pingouin Jul 12 '16 at 6:25
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I think you've got this a bit backwards; evolution is always the result of 'accidental' mutations. There's no reason that people in the north have to be paler than their southern relatives, it just so happens that that's an advantageous trait to have. It's very unlikely that it would simply not occur in human history, however it could have arisen later and been more isolated.

Mutations occur randomly every time an animal reproduces; each offspring is a combination of its parents genes with a handful of errors made. Any mutation is, in effect, equally likely, so the chance of first getting the light skinned gene is pretty darn certain over tens of thousands of years. Once you have one individual with a trait you move over to natural selection; if the mutated child has an advantage (which pale skinned people do in northern climates) then they will reproduce 'more' and therefore pass on their pale skinned gene to more offspring than otherwise. This continued until they supplanted the dark skinned population.

(I'd like to point out that based on current human behaviour it's entirely possible that the spread of the gene was helped by people finding the new skin colour attractive.)

In your hypothetical scenario everyone would indeed have dark skin, though differences in stature and facial structure would be more than sufficient for these people to distinguish different ethnicities.

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