Why do Caucasians have such a wide variety of hair colours and textures, and eye colours?

Question

Everyone else, bar one blonde mutation in aborigines and some nearby islands, have black hair. If Africa is the worlds most ancient population, shouldn't they have the most mutations for hair color and texture? Aborigines show that being blond isn't a disadvantage in a tropical climate. Straight hair isn't either (Southern India, central America).

How did such a huge variety arise in such a small and new population. Why is the oldest one so limited?

All theories welcome.

Answer 1

Mendel got it wrong.

Answer 2

This is why sequencing of ancient DNA is so important.  Like many I suspect some gene introgression to & from the sapien line by neandertal & erectus.  So far gene sequencing has produced "no" evidence that the Homo line could not interbreed.  So far the neandertal genome tests to be 99.96% of the sapien gene... about 3X the normal deviation of the genome among modern humans.

Upon close examination the erectus was far closer to modern humans in physical structure than was the neandertal (neandertal having a much more robust & compact build, with an A shaped rib cage.)  The ginger gene (red hair & freckles) appears only in the Mid East & Europe... but I also suspect some degree of gene introgression among erectus & neandertal.  Migration in the past few 1000 yrs appears to have spread the gene to areas speaking some of the Ayran languages.  I suspect blue eyes are exclusively a neandertal gene.

Because both neandertal & erectus had 100s of thousands of years to evolve to live in their environment, before sapien arrived, one must suspect they were better evolved to fit the environment than the new arrivals.

Being familiar with "hybrid vigor" where hybrid plants & animals often do far better in an environment than either parent species, I have to suspect interbreeding allowed the new comers to scarf up some of the beneficial genes contained by the older occupants.

We have many mysteries to solve & though it may hurt the careers of some biologists & anthropoligists, we should plow full speed ahead on solving them.

Answer 3

Genetics & natural selection.

By the way, there is even more variation of features among African peoples.

Answer 4

This is a great question. One theory I've read of how blonde, blue eyed people came about is all to do with s*x selection of females. Most caucasions are fair haired as children so being blonde is associated with being young. Life expectancy was low in early Europe so women had children at an early age. Blonde women looked younger than brunettes so they were positively selected for by men looking for young partners. However there was no such selection pressure working to promote blonde men since "youth" is associated with lack of resources and lack of power for men. Even today white women often look for tall dark and handsome and men look for blonde and beautiful. The different selection pressures on men and women have led to a balance between the number of blonde blue eyed people and brunette brown eyed people in Europe.

Edit: Mathilda I don't know why you think scientific truth is necessarily consistent with feminist ideals! The evolutionary changes we are talking about took place at a time when men bought and sold women into marriage. Women were not generally the ones selecting men BUT if a particular woman was in a position to choose a mate in that culture she would certainly choose a more mature rich man if she wanted her children to survive. So I stand by the theory.

Answer 5

I am going to give a possibly controversial answer on this one. My own theory is that while Africa is the worlds oldest population its genetic code is made up almost entirely of "modern" humans as opposed to Caucasians who would most likely have a mixture of Neanderthal and Cro-Magnum ancestors and that those of East Asian descent would most likely be a mix of "modern" humans and Homo erectus ancestors. Red and blonde hair as well as blue and green eyes were genetic characteristics originally found primarily in Neanderthals which would explain why they are found primarily in people of European descent.

Answer 6

No need to brush off Keypoint's answer just because you don't like it.  And no, in those days, men were the ones doing the dominating, and therefore the selecting.  

We probably started with ordinary brown hair and brown eyes.  Then, somehow some individuals with blond hair, or red hair, and light eyes arose.  Because these individuals had hair and eye colors that were rarer and "flashier" than the more common brown hair and brown eyes, they were selected for moreso than their brown-haired, brown-eyed counterparts.  

Natural selection is the reason why almost all traits that exist in the human population exist today.  If blonde hair and red hair are recessive (compared to darker hair colors) then there would just about HAVE to have been strong natural selection favoring them.

Answer 7

Hi Mathilda It's not often you are right, But your wrong again.

Answer 8

You said, "Sexual selection in the real world is mostly females picking traits they like in males"

If this is true, my sisters are destroying the human genome (just kidding).  I certainly agree that selection of males is not really selection it seems.  It is more like finding anything that moves or doesn't move too fast.  

I think not having as much melanin, allows for the other colors, much as not having chlorophyll allows colors in leaves.

Answer 9

According to this Scientific American article, eye color and hair color are a result of melanin levels. Less melanin in northern Europeans led not only to lighter skin pigmentation, but also to blue/green eye pigmentation and brown/blonde hair. Look at where blonde hair is most common: Scandinavia! Certainly these characteristics may have spread through sexual selection. There is no evidence that Neanderthals had these characteristics, or that they might have been the source of them in modern humans.

Answer 10

We have got a lorra bottle. I'm am so glad I'm not a proud conservative.