skin colour

[dannyday5821]

I want to make it VERY clear im not being racist before anyone says anything, im really curious thats all...

I was just wondering why their are actually different people and races and countries and so on that have different coloured skin. I mean whats the point? What benifit does black skin have over white skin? if any? or the other way around. Is it an "evolution" thing? If so why? if it is, then evolution will have done it for a reason. (lol - or god will have done which ever you choose! - although if so why would god even do it?) At a seriously uneducated guess, id say some people have white skin because it helped absord sunlight cuz its a cold climate, and black skin is to repell the heat from the sun...that sounds stupid doesnt it...

but seriously, im curious...

[gen2]

Quote:
"id say some people have white skin because it helped absord sunlight cuz its a cold climate, and black skin is to repell the heat from the sun...that sounds stupid doesnt it..."

YES.

It is in fact the opposite: Black absorbs heat/light, White reflects heat/light.

Your earlier guess that it is an evolutionary thing is correct. We are all aware nowadays of the harmful effects of UV sunlight if it penetrates the skin as far as the basal layer. Melanin (the dark pigment) absorbs this UV reucing the short-term damage of sunburn and the long-term damage of skin cancer. Evolution has therefore selected for dark skins in those parts of the world where there is strong sunlight. Even in temperate regions, lighter skinned people boost production of melanin in response to sunlight (tanning).

The other side of the coin is that there is a disadvantage to having dark skin in parts of the world with weak sunshine. A major source of vitamin D is your own skin which produces it with the energy of sunlight. If the skin is dark and insufficient light can get through, then there is a risk of developing rickets. Evolution has thus selected for lighter skin tones in higher latitudes.

[dannyday5821]

wow brilliant answer! thanks gen2! im now a little wiser...

[VorVZakone]

hmmm. I'm not sure about some parts of gen2's answer.
I cannot see how it would really have occurred other than through evolution, in that respect we agree. But the key is in *evolution*. Came from one state, became another, through an adaptive advantage that was selected for. We definitely *came* from darker skins, from Africa, before we moved off to Europe. Why isn't everyone in Europe black, still? I think the original post is pretty good, I like the idea of lighter skin being selected for, to absorb sunlight better (vitamin production, etc). For sure, evolution doesn't just 'naturally' lose traits when it thinks they're no longer necessary.
I wonder about the skin cancer element too. Is this really going to have a big enough impact in a short lifespan? Is it enough to make people turn *Black*?

[gen2]

VorVZakone, I don't claim to be an expert in this field and have simply given what I was told by my university lecturers. I stick by my statement that high levels of melanin provide greater protection from sunburn and cancer, though I do concede that most of the evolutionary pressure will be from the sunburn since cancer is unlikely to develop early enough to affect reproductive rates. Although sunburn doesn't kill directly, it could lead to reduced efficiency for hunter-gatherers and without antibiotics, severe sunburn could lead to skin infections. I imagine children would be most vulnerable and increased mortality before sexual maturity would remove them from the gene pool - a strong evolutionary pressure.

As for your comment about black being lost when early humans moved into Europe, I agree that a trait will not be lost, or deselected just because it is no longer needed. What I said was that lighter skin tones would be positively selected for. Skin colour is determined by many different genes and so this change would not have to be an 'all-or-nothing' change. These changes could come about either by the chance coming together of rare genes in the existing gene pool, or by new mutations being selected for and accumulating over time. I did not specialise in genetics so cannot go deeper into that aspect of it.

[eyebrows]

black skin allows you to steal and get away with it

[4getmenot]

Uh Oh

[SKA]

more pigment making darker skin helps to reduce skin cancer so people generally are darker in sunnier countries.

^ eyebrows - pathetic

[newtron]

Do you think social issues may have also played a role in a certain skin colors becoming dominant in certain regions? For instance, once a small population of a people with different skin color is established by different evolutionary forcing mechanisms mentioned above, people of like color would most likely mate with each other due to prejudices. This might speed up the process of the evolution of specific race.

[Robb Phoenix]

Here is part of the evolutionary story from latest research:
Long long ago Humans roamed in the grasslands of Africa.
Then some decided to migrate out of the continent but as they moved northwards since white skin was favorable to colder climates due to the reasons stated above some mutated to have fair skin. Thus,
!!!!!!!!!!!! We are MUTANTS !!!!!!!!!!!

[VorVZakone]

gen2: I have studied evolution at university, in depth, but you seem to have a much better grasp of it than me. You're probably one of these biology types that has to do it hardcore. Well done. Good post.

[Robb Phoenix]

newtron
Humans by default are BLACK,
So only very few must have been white in the beginning, so there must have been no prejudice then.
Prejudice only arose when the white populace grew and when we forgot our roots and thought that we were the pure descendants of the original human race and that we had a God given task to "enlighten" the Blacks who were as we had believed "uncouth"and "backward" people who needed to be "tamed" by us. Thus we went about occupying nearly the whole of Asia and Africa and started discrimination and the Apartheid.
Personally I have no problem in marrying a woman of any color.I only look for beauty both physical and mental.I believe most of the others must have thought so in the past,will be thinking at present and would think so in the future too.

[VorVZakone]

I would have a problem marrying a black woman, I'm just not attracted to them. I find far east asian women very attractive though. Have you ever seen a woman that is half chinese half malasian?
Was the first homo sapiens black? Or a bit darker than modern whites, but became darker through the selective advantage it gave. Blackness protects you from damaging effects of the sun: but you really only need this to a great extent if you don't have that much hair. Walking upright presents a lot more to the sun too.
There's a theory that there was a separate homo line at the same time out of China?
If the original hominid was black, why is there no bling found at the early burial sites? (sorry).

[newtron]

Maybe "prejudice" was the wrong word, but the root of prejudice is most likely that fact that one group of people is different in some way from another group of people. The rationalization of why the groups are different and that one group is better than another is surely secondary. If the majority of people were black, then it is possible that the blacks ostracized the strange light skinned folks, and this segregation may have accelerated the evolution of individual human races. I am no expert on human evolution, so this is all speculation. However I wouldn't be surprised if human culture and social interactions play a role in human evolution.