Why are there white people?

Question

I'm serious. We started in Africa as humans. We were dark skinned, which was an advantage because of the sunlight and heat. Some humans moved north into Europe. These people became white. Why? Just because there is less sun is not a reason for genetic change. There must have been a benefit to lighter skin in that region. What was it? In other words; if the darker skin color was no longer necessary, why did it go away instead of becoming vestigial?

Folks. For those of you who are posting it. I'm not black. Please no more stupid racist answers. Back up your responses with facts and logic.

Answer 1

There are white people because:

Black skin blocks sunlight more effectively, enabling those of us who are in Africa to protect themselves against skin cancers caused by large amounts of ultra-violet light (which you tend to get more of the closer you are to the equator).

However, as we moved North thousands of years ago, those of us who had darker skin found that their dark skin, plus the relative lack of sunlight, inhibited the production of vitamin D3, which is essential for bone growth (among other things). Those humans with lighter skin were more able to generate vitamin D3 from sunlight, because their skin didn't block sunlight so much. Thus, people with lighter skin were favoured by natural selection.

Contrary to what somebody else said, black and white people are not different species. The genetic differences between black and white humans are insignificant.

Answer 2

The benefit is protection. The pigment that causes skin color is called melanin produced by melanocytes. Melanin helps protects your body against the sun and things like high temperature. It doesn't really depend where humans originated and if they migrated, the reason for skin color would be the same. In places near the equator, the concentration of sunlight is higher and more melanin is needed to protect the body. However, this also means that there is enough sunlight to penetrate the skin to ensure the body obtains all the nutrients it needs. So, people with darker skin are at risk of certain vitamin deficiencies when living in places with a lower amount of sunlight. The same holds true for people with light skin in areas with a high concentration of sunlight. These people are more at risk for things like skin cancer (for the same reason as not using sun tan lotion at the beach). Actually, I've heard that a few Nazis that fled to Brazil after WW2 died of cancer due to their exposure to the elements. As for genetics, over a long period of time (if all life originated in Africa) the people who migrated north would have time to make this adaptation genetic, and indeed benefited from it. While the people who stayed near the equator kept the darker skin to help with the sun.

A fun fact: The condition albinism is when the body produces no melanin. Since melanin provides protection from the sun this leads to many health risks including a high risk of cancer.

Answer 3

We did not start as dark skinned - most likely mid-brown.

Everyone has brown skin, just different shades. The brown is caused by melanin in the skin. Natural selection has resulted in some people with darker skin than others - just like some people have lighter hair, or wavier hair.

Check here for an article giving loads of detail on this and more
http://www.creationontheweb.com/images/pdfs/cabook/chapter18.pdf

Incidentally there are no such things as 'vestigial' organs. This is an evolutionary myth!
The purpose has now been found for hundreds of organs once thought to be evolutionary left-overs.
http://www.creationontheweb.com/content/view/3039/

Answer 4

It's a response to the vitamin D poor diet of neolithic farmers.

Prior to the introduction of agriculture in northern Europe people got all the Vitamin D they needed from eating animals, the kidneys and livers specifically.

The diet of grain introduced by migrants from the Middle east lacked vitamin D but had the precursors for it.

If you get enough sun your body can synthesize it from the right materials, but the sunlight has to make it past the skin. It's cloudy in northern Europe with fairly short days in the wintertime. So skin color was a more critical factor there than it was in the middle east.

Inadequate Vitamin D form either intake or synthesis produces skeletal growth problems and deformities. These deformities can be crippling and even mild cases would raise the risk of death in childbirth for women whose hips didn't grow quite large enough to accommodate their offspring's skulls at birth.

The effect of the Vitamin D problem was to place selective pressure on darker skin. Lighter skinned individuals had more children and individuals with mutations that produced unusually light pigmentation enjoyed more reproductive success than their darker contemporaries. Over time selective pressure weeded out the genes for dark pigmentation and viola. Whitey.

Answer 5

I'm amazed at the number of people who think there is enough distinction between black, white, yellow etc folks to consider they could be different races (or even species as a few have suggested).

Come on - we're all so similar in mind, body and especially soul!

Anyway - I have also been interest in similar geographical differences among populations.

In similar vein to white skin, I have always wondered about freckles and red hair. What's that all about?!

Plus, being Irish I have plenty of friends who almost cannot go out in summer sunshine for fear of burning. This seems quite unhelpful as an evolutionary change.

It is like the adaptation to poor sunlight has been taken to an extreme. Yet the trait is not rare in the population of the British Isles.

Thanks for the good question. It's very sobering to see so many ignorant responses to your genuinely interesting question - it's let me feeling pretty depressed about things :(

Answer 6

NO. NO. NO. The whole black skin and vitamin D3 thing is crap. These people lived their lives out doors, they would have certainly sythesized sufficient alpha 1,25-dihydorxycholecalciferol (he he) to have been quite healthy.

I don't really know the answer but I think the above dosn't cut it.

My guess is that is was a socialogical sexual selection thing rather than a nutritional thing.

Light skin would have been a rare trait and as such might have been looked upon favorably when choosing a mate. (sort of like blue eyes today??). Over time sexual selection for lighter and lighter skin in that culture would have given rise to the Waspy-McWaspersons we know and love today.

Answer 7

Funny thing: I was reading about this the other day and gave an answer to another question that also answers yours. I wrote:

Since we are all descended from dark skinned Africans, when did the light skin of Europeans arise?

Well, it turns out that it wasn't so long ago. Largely, the light skin is a result of changes in a gene called SLC24A5. Europeans mostly have a particular change in the gene that leads to lighter skin. This is selected for because it allows people to make enough vitamin D in their skin even in places like northern Europe that don't get much of the sunlight necessary to make the vitamin. By looking at the DNA sequence surrounding the gene, researchers now think that the mutation that caused light skin may have arisen only about 5,300 - 12,000 years ago. Because of the selective advantage the mutation generates in vitamin D synthesis, it spread rapidly through the early European population. (The lab of Michael Hammer, University of Arizona.)

Hope you read down this far to see this.

BTW: to answer the person above me, red hair often results from mutations in a gene encoding the melanocortin receptor = when the gene is mutated, the person doesn't make melanin properly, and they have red hair. The different shades of red hair result from slightly different mutations and from interactions with the other genes the person is carrying.

-----

Edit:

michaelhobbsphd and shannon_ida, below me, can opine all they want, but they are going against the well established scientific consensus that white skin is related to vitamin D metabolism. To quote the April 20, 2007, issue of the journal of the American Association for the Advancement of Science, Science:
"Under darker skies, pale skin absorbs more sunlight than dark skin, allowing ultraviolet rays to produce more vitamin D for bone growth and calcium absorption. 'The [evolution of] light skin occurred long after the arrival of modern humans in Europe, ' molecular anthropologist Heather Norton of the University of Arizona, Tuscon, said in her talk."

The journal was reporting on the meetings of the American Association of Physical Anthropologists.

Answer 8

I agree with Micheal, we as humans are attracted to things that are different, like blue eyes. I don't mean to offend by comparing us to dogs but when you breed dogs you breed together 2 animals with traits that you want to keep, from their litter you take the pups that have those traits and breed them with others that have traits you want to keep. The same holds true with humans. When you see someone you are attracted to and you have children you will say to yourself, "I hope the baby has their eyes" or nose or chin or whatever. But you are causing the same type of genetic selection that would happen in animals. When light skin was a rarity it was considered beautiful and light skinned people were more likely to be chosen as mates. As such, the skin got lighter and lighter until eventually you have the liquid paper white skin that we find so attractive today.

Answer 9

Good Question. There are many theorys on Evolution, to answer your question this is the one that I prefer:

Human beings actually have one of the smallest gene pools of all mammals considering the number of them that exist, there are basically 7 main races which can be expanded into 10 more refined ones : Caucasian, African, Middle-Eastern, Asian, Inuits, Native Americans, Native South Americans, Aboriginal and Mayan.

The reason is for the same reason we all look different to each other - Genetic Mutation. Some scientists think the reason we have such a small gene-pool is due to a major event that occured wiping out most of the human race and we all decended from these small groups (theories include Noah's flood, the ice-age, a giant radioactive meteor). The oldest skeleton is 4 million yrs old and was found in Ethiopia but this does not conclusively mean humans were only found in Africa at this time. Its also important to remember that 4 million years ago Africa wouldn't have been in the same place it is now as the continents move around.

If you consider dogs for example - they come in many sizes, shapes and colours. So I guess the important question should not be why are we so different, but more why are we so much the same.

Hope this helps!

To the people posting offensive/racist comments - this is a very valid question and it is you who are the idiots!

Answer 10

The fact that there was less sunlight is actually a reason for a genetic change, but it certainly wouldn't have been immediate. When the body realizes there's no reason to continue making pigmented skin (even just during the winter months) we stop making it. Then, when we start getting a lot of sun exposure, our skin darkens. Now, it went away instead of becoming vestigial because eventually evolution just gets rid of vestigial elements of our bodies. We don't need them, and it goes away. But as I said skin color certainly didn't fade in the same way our summer tan does by November. It would have been a slow enough process to make the difference in genetics.

Answer 11

I don't consider evolving to white very advantageous. As I pretty much have to be a hermit during the summer or slather on SPF 80 all day. :P

I think it was an "attractive mutation"? Enough normal dark people found the strange light people attractive enough to mate with them and pass on the genes.

I like the Vitamin D theory though, sounds intelligent enough.

vive la difference