# evolutionary signifcance of "white" skin?? **URL:** \ **Category:** Factual Questions\ **Created:** [October 15, 2004, 1:48am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301 "2004-10-15T01:48:25Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Flipshod](https://avatars.discourse-cdn.com/v4/letter/f/f19dbf/32.png) [@Flipshod](https://boards.straightdope.com/u/Flipshod)\ **Post date:** [October 15, 2004, 1:48am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/1 "2004-10-15T01:48:25Z")
My pop-science understanding leaves me with: Genetisists show that we all come from a single woman in Africa. Modern people from Africa don’t have “white” skin. So I assume that “white” skin was a later evolotionary devlopment. My question: What natural circumstance arose that selected “white” skin? Is it a geographical thing? Is it a random by-product of a geographical thing? Or is it an aesthetic feature that arose after social and cultural circumstances became more important indicators of breeding success than geography?? And BTW, when did human mating and breeding success go from geography to sociology? I offer this question in scientific good faith only. ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [October 15, 2004, 2:02am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/2 "2004-10-15T02:02:26Z")
High amounts of pigment in the skin help to protect against sunburn and skin cancer and whatnot. This is important in tropical and desert areas where there is intense heat and sunlight. As people started migrating away from Africa, especially towards temperate and cold areas in Europe, there was no longer much of an advantage to producing this pigment. So people whose bodies did not waste as much energy producing skin pigment had an advantage, and reproduced more, leading to white skinned Europeans. ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [October 15, 2004, 2:02am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/3 "2004-10-15T02:02:52Z")
Vitamin D. Vitamin D can enter the body when eaten in fish or the body can synthesize it when subjected to a certain amount of UV radiation in sunlight. Since the production of melanin is a cost to the body, when various persons experienced a mutation that seriously reduced melanin production, those who lived in the Northern Latitudes had a better chance of success. (Darker skin means that you need more sunlight exposure to generate Vitamin D. Lighter skin means you can get by on less sunlight. Mutations that reduced melanin in climes closer to the Equator would have harmed the individual by allowing skin burns and skin cancer, so it was only selected in regions where there was less sunlight and those people, while not needing melanin protection would need a way to absorb more UV light.) ---
**Author:** ![PaulFitzroy](https://avatars.discourse-cdn.com/v4/letter/p/2acd7d/32.png) [@PaulFitzroy](https://boards.straightdope.com/u/PaulFitzroy)\ **Post date:** [October 15, 2004, 2:10am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/4 "2004-10-15T02:10:40Z")
How did that result in the changes in the shape of the skull and other things like thinner lips, a higher forehead, and all that? ---
**Author:** ![Cooper](https://avatars.discourse-cdn.com/v4/letter/c/50afbb/32.png) [@Cooper](https://boards.straightdope.com/u/Cooper)\ **Post date:** [October 15, 2004, 2:14am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/5 "2004-10-15T02:14:49Z")
> [@PaulFitzroy](#): > > How did that result in the changes in the shape of the skull and other things like thinner lips, a higher forehead, and all that? Likely these are not adaptive changes at all. Rather, they are simply variances in genetic convergence - localized by the geography. In other words, totally random and meaningless, just like difference in language, culture and religion. ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [October 15, 2004, 2:21am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/6 "2004-10-15T02:21:23Z")
> [@](#): > > How did that result in the changes in the shape of the skull and other things like thinner lips, a higher forehead, and all that? Who said that it did? The question was “where did white skin come from?” Other morphological changes could be as simple as random mutation followed by a founder effect during migration. Unlike skin pigment, I am unaware of any purported advantage to the height of the forehead. _If_ there are advantages to the shape of the lips (as there have been purported advantages to the _general_ shapes of noses, they would have been selected in the same fashion: some mutation tends to work well in one environment while providing a disadvantage in another environment leading to a general selection for or against depending on the environment. ---
**Author:** ![vanilla](https://avatars.discourse-cdn.com/v4/letter/v/f19dbf/32.png) [@vanilla](https://boards.straightdope.com/u/vanilla)\ **Post date:** [October 15, 2004, 2:32am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/7 "2004-10-15T02:32:36Z")
I’d thought it was fading. Sortof like when one keeps making copies off an original. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [October 15, 2004, 2:46am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/8 "2004-10-15T02:46:15Z")
> [@friedo](#): > > High amounts of pigment in the skin help to protect against sunburn and skin cancer and whatnot. This is important in tropical and desert areas where there is intense heat and sunlight. As people started migrating away from Africa, especially towards temperate and cold areas in Europe, there was no longer much of an advantage to producing this pigment. So people whose bodies did not waste as much energy producing skin pigment had an advantage, and reproduced more, leading to white skinned Europeans. Given that skin cancer mostly occurs after the reproductive years, a more important selective factor for dark skin may be protection against folate, a B-vitamin. From [here](http://en.wikipedia.org/wiki/Human_skin_color): > [@](#): > > Dark skin protects against skin cancer, mutations in skin cells induced by ultraviolet light. Light-skinned persons have about a tenfold greater risk of dying from skin cancer under equal sun conditions. Furthermore, dark skin prevents UV-A radiation from destroying the essential B vitamin folate. Folate is needed for the synthesis of DNA in dividing cells and too low levels of folate in pregnant women are associated with birth defects. > > The advantage of light skin is that it lets more sunlight through, which leads to increased production of vitamin D3, necessary for calcium absorption and bone growth. The lighter skin of women results either from sexual preference or from the higher calcium needs of women during pregnancy and lactation (also possibly from both). > > The evolution of the different skin colors is thought to have occurred as follows: the haired ancestor of humans, like modern great apes, had light skin under their hair. Once the hair was lost, they evolved dark skin, needed to prevent low folate levels since they lived in sun-rich Africa. (The skin cancer connection is probably of secondary importance, since skin cancer usually kills only after the reproductive age and therefore doesn’t exert much evolutionary pressure.) When humans migrated to sun-poorer regions in the north, low vitamin D3 levels became a problem and light skin color evolved. ---
**Author:** ![Flipshod](https://avatars.discourse-cdn.com/v4/letter/f/f19dbf/32.png) [@Flipshod](https://boards.straightdope.com/u/Flipshod)\ **Post date:** [October 15, 2004, 3:46am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/9 "2004-10-15T03:46:25Z")
thanks all, so there is an energy cost for producing melanin so “white” skin survives because _that_ piece of energy now goes to some other adaptive feature? ---
**Author:** ![Flipshod](https://avatars.discourse-cdn.com/v4/letter/f/f19dbf/32.png) [@Flipshod](https://boards.straightdope.com/u/Flipshod)\ **Post date:** [October 15, 2004, 3:48am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/10 "2004-10-15T03:48:24Z")
oh, OK thanks ---
**Author:** ![Chairman\_Pow](https://avatars.discourse-cdn.com/v4/letter/c/838e76/32.png) [@Chairman\_Pow](https://boards.straightdope.com/u/Chairman_Pow)\ **Post date:** [October 15, 2004, 3:49am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/11 "2004-10-15T03:49:49Z")
Is producing melanin really that wasteful energy-wise that not making as much is helpful in figuiring out who is going to live through the winter (when not as much Vit-D will be absorbed)? How much energy are we talking about? ---
**Author:** ![ouryL](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ouryl/32/6067_2.png) [@ouryL](https://boards.straightdope.com/u/ouryL)\ **Post date:** [October 15, 2004, 3:55am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/12 "2004-10-15T03:55:34Z")
> [@Flipshod](#): > > My pop-science understanding leaves me with: > > Genetisists show that we all come from a single woman in Africa. > Modern people from Africa don’t have “white” skin. > So I assume that “white” skin was a later evolotionary devlopment. > > My question: > What natural circumstance arose that selected “white” skin? > > Is it a geographical thing? Is it a random by-product of a geographical thing? > > Or is it an aesthetic feature that arose after social and cultural circumstances became more important indicators of breeding success than geography?? > > And BTW, when did human mating and breeding success go from geography to sociology? > > I offer this question in scientific good faith only. I think you got it backwards. Shave an animal and all you see is “white skin”. Pigmented skin a development from being nude. ---
**Author:** ![ouryL](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ouryl/32/6067_2.png) [@ouryL](https://boards.straightdope.com/u/ouryL)\ **Post date:** [October 15, 2004, 3:59am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/13 "2004-10-15T03:59:03Z")
> [@PaulFitzroy](#): > > How did that result in the changes in the shape of the skull and other things like thinner lips, a higher forehead, and all that? Change in diet. Humans began becoming omnivores/carnivores instead of herbivores. Large teeth and heavily muscular jaws no longer have the advantage in survival. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [October 15, 2004, 4:08am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/14 "2004-10-15T04:08:42Z")
> [@Flipshod](#): > > thanks all, > so there is an energy cost for producing melanin > so “white” skin survives because _that_ piece of energy now goes to some other adaptive feature? Not really. White skin developed in order to permit better synthesis of vitamin D in areas with low solar radiation. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [October 15, 2004, 4:11am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/15 "2004-10-15T04:11:29Z")
> [@ouryL](#): > > Change in diet. Humans began becoming omnivores/carnivores instead of herbivores. Large teeth and heavily muscular jaws no longer have the advantage in survival. I think **PaulFitzroy** was referring to what he perceives as “Caucasian” type features relative to those of some populations in sub-Saharan Africa. But there is no real correlation between the morphological features he mentions and skin color. ---
**Author:** ![Bob55](https://avatars.discourse-cdn.com/v4/letter/b/e9c0ed/32.png) [@Bob55](https://boards.straightdope.com/u/Bob55)\ **Post date:** [October 15, 2004, 6:07am UTC](https://boards.straightdope.com/t/evolutionary-signifcance-of-white-skin/269301/16 "2004-10-15T06:07:43Z")
> [@Flipshod](#): > > Genetisists show that we all come from a single woman in Africa. I don’t think this means we all actually came from this one woman alone, but that based on the differences in our 16S mitochondrial DNA (which comes from our mother) the convergence says that we’re all related to a single woman hundreds of thousands of years ago, but we’re also probably related to almost every other human alive at that time. It is possible there were variations in skin color at that time since a cooler climate in Africa might have forced people to cover up more.