More likely melanin is a mutation, or the lack of it is?

Question

If you've considered the idea that people were white and then darkend you'll come across people saying melanin is a proof that People were dark and whites/asians lost that gene for better vitamin D absorption. If you look at it the other way however melanin is more likely to stop overdoseing of melanin, hence it would be the mutation to have rather too not have it.

Also white people can get dark in the sun, as of tanning, but they also get permanent darking from overexposure. Freckles and other sun exposure related browning that gets past on through genetics.

Answer 1

Kriss, because the oldest haplogroups of humans are located in tropical or semi tropical areas of Asia, as well as Africa, it appears as if dark skinned people migrated out of Africa & due to the need for vitamin D, as you pointed out, their skin lightened as they moved north.  I suspect you know that lack of vitamin D causes rickets, causing women to die in natural childbirth.

Now as for the darkening of skin among white skinned people, that is to regulate the amount of sunlight. Too much sunlight depletes folic acid, thus causing birth defects in the offspring.  Therefore one finds that skin color is important to the production of offspring, thus giving those with the proper color skin a reproductive advantage.  All positive gene selection eventually boils down to the number of offspring that survive to a reproductive age & do so.

The groups that migrated out of Africa, but stayed in tropical environments (Negritos  & Australian Aboriginals) kept their dark skins, but did develop other mutations.  Aboriginals do have some blond hair or light brown that appears from time to time.

Mathilda voiced another hypothesis, that I tend to support, but I gave you the other side of the coin on skin color.  Because the Neandertal & Homo erectus had 100s of thousands of years to evolve before sapiens appeared, it is very possible the sapien picked up some of their genes.

Answer 2

Its governed by gene, all genes do what they do as a result of prior mutation, and all are subject to future mutation.

Answer 3

Melanin, or pigment, makes the skin it's natural. It's also in eyes, and hair.

In hot climates (ie more sun) it protects the skin. However, it's not complete protection. In higher latitudes less of melanin allows for the absorbson of vitamin D. There have been cases where dark skinned people in high latitudes suffered vitamin deficiencies.

Tanning is caused by the production of more pigment following exposure to the sun. Too much sun can cause sunburn and cancer. Australia has one of the highest rates of skin cancer in the world.

Too much exposure damages the skin  can lead to wrinkles, freckles, "Liver spots", benign skin tabs and so on.

In terms of evolution, humans evolved in Africa and spread out from there. Coming from a sunny climate means we began dark and, due to geographic location, became lighter in color

Answer 4

All genes are mutations from something else.

There's more and more evidence now that (from the X chromosome) we picked up genes for light skin and red/blonde hair from Neanderthals, as we know they were light skinned. The mutations are on the MCR1 gene, and a mutation for red hair also affects skin colour, lightening it. We have to sequence a few more Neanderthals to find out.

So the answer to your question is... dark skinned people didn't' mutate into light skinned. We probably borrowed the genes from elsewhere.

Answer 5

Perhaps everyone was light brown originally, like the San-Bushmen, who represent the root of all ancient H. sapiens DNA?

If that were the case, as early humans migrated away from the shaded jungles to the coastal areas, those individuals through natural selection, became much darker (as the sun's rays are least forgiving near the ocean), and those who continued North by Northeast, and began to encounter clouded regions, season after season, began to lighten in skin & eye color, as well as hair texture!