# Would white people stuck in an island eventually evolve to black? **URL:** \ **Category:** Factual Questions\ **Created:** [August 21, 2010, 3:28pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970 "2010-08-21T15:28:02Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![Livardo](https://avatars.discourse-cdn.com/v4/letter/l/43a26b/32.png) [@Livardo](https://boards.straightdope.com/u/Livardo)\ **Post date:** [August 21, 2010, 3:28pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/1 "2010-08-21T15:28:02Z")
By “eventually” I mean, through evolutionary processes. First let me preface by saying I know very little about evolution. Whatever I was taught in highschool is just a haze now. I’m not a creationist either. I’m just curious about the subject. Let’s pretend we have a colony of 500 white people suck in a small island right at the equator. The island has some trees but exposure to the sun is continuous and inevitable. The growth rate is kept at 0% so they’re basically replacing themselves. If someone can explain the process in layman terms that’d be great as well. cheers! ---
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [August 21, 2010, 3:36pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/2 "2010-08-21T15:36:34Z")
My incredibly layman’s understanding is that people of darker skin would have a slightly better chance of surviving long enough to reproduce due to the hot climate favouring darker skin, and therefore over a long period of time (many generations) the skin of the population would get darker and darker as the darker skinned survivors pass on their dark skin genes. ---
**Author:** ![qpw3141](https://avatars.discourse-cdn.com/v4/letter/q/6bbea6/32.png) [@qpw3141](https://boards.straightdope.com/u/qpw3141)\ **Post date:** [August 21, 2010, 3:39pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/3 "2010-08-21T15:39:17Z")
If there was a lot of hot sun those with the lightest skin would be most likely to suffer from skin cancer. So over many thousands (tens of thousands) of generations those who produced more melanin would have a better chance of survival than those who produced less. Any random mutations that caused an increase in melanin production would be favoured. Of course, most ‘white’ people can actually go pretty dark if they are continuously exposed to a lot of sunlight so the effect might not be very pronounced. A more interesting question, IMO, is what evolutionary advantage did having **lighter** skin have confer that caused people who migrated to cooler climes to lose their colour. ---
**Author:** ![RickJay](https://avatars.discourse-cdn.com/v4/letter/r/bb73d2/32.png) [@RickJay](https://boards.straightdope.com/u/RickJay)\ **Post date:** [August 21, 2010, 3:39pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/4 "2010-08-21T15:39:21Z")
> [@Livardo](#): > > By “eventually” I mean, through evolutionary processes. > > First let me preface by saying I know very little about evolution. Whatever I was taught in highschool is just a haze now. I’m not a creationist either. I’m just curious about the subject. > > Let’s pretend we have a colony of 500 white people suck in a small island right at the equator. The island has some trees but exposure to the sun is continuous and inevitable. The growth rate is kept at 0% so they’re basically replacing themselves. > > If someone can explain the process in layman terms that’d be great as well. > > cheers! The population would evolve, assuming it could be kept going. Whether it evolved into black people you don’t really know. Assuming that people are selected for darker skin, which in your scenario seems a reasonable guess, then yes, over enough time, assuming the population kept going, it’s possible that their skin would become darker. That doesn’t necessarily mean they would become “Black” in the sense you probably understand it, meaning looking like West Africans; curly hair, larger lips, that sort of thing. They might have darker skin the way Sri Lankans do, for instance. They might look like the Melungeons. In this case the way evolution is working is by natural selection. We’re assuming that dark skin is a survival trait; that people with slightly darker skin have a better chance of passing on their genes than people with lighter skin (I would assume because lighter skin increases your chances of getting skin cancer.) However, people being people, it seems equally likely your population would not so evolve simply because it’s unlikely that the likelihood of skin cancer will ever have an effect on breeding likelihood. People are pretty good these days about staying out of the sun, after all. You might see other evolutionary changes though. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [August 21, 2010, 3:45pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/5 "2010-08-21T15:45:39Z")
> [@RickJay](#): > > We’re assuming that dark skin is a survival trait; that people with slightly darker skin have a better chance of passing on their genes than people with lighter skin… Along comes a Zebra stripe mutation, with its slightly darker _average_ skin color. The ladies find it especially attractive, so within a few generations, everyone is stripey, despite the somewhat better protection from cancer offered by uniformely dark pigmentation. ---
**Author:** ![SmithCommaJohn](https://avatars.discourse-cdn.com/v4/letter/s/ecd19e/32.png) [@SmithCommaJohn](https://boards.straightdope.com/u/SmithCommaJohn)\ **Post date:** [August 21, 2010, 3:53pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/6 "2010-08-21T15:53:56Z")
> [@qpw3141](#): > > A more interesting question, IMO, is what evolutionary advantage did having **lighter** skin have confer that caused people who migrated to cooler climes to lose their colour. If I remember from college anthropology (just a general ed requirement, I’m by no means an expert, so correct me if I’m wrong), lighter skin is more conducive to the production of Vitamin D than darker skin. Vitamin D can be produced in the skin, when it’s exposed to ultraviolet light, and we need Vitamin D to live. At higher latitudes, with less UV light, the risk of skin cancer was much lower. Of course, vitamin D production was also lower, so people evolved lighter skin to make use of what UV light they could get. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 21, 2010, 3:54pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/7 "2010-08-21T15:54:11Z")
> [@](#): > > A more interesting question, IMO, is what evolutionary advantage did having lighter skin have confer that caused people who migrated to cooler climes to lose their colour. Vitamin D production. Our skins produce vitamin D when exposed to sunlight, and with less sunlight available, we had to do so more efficiently. Of course, in our modern age of sunscreen and fortified milk, it doesn’t really make much difference either way. ---
**Author:** ![Simplicio](https://avatars.discourse-cdn.com/v4/letter/s/c37758/32.png) [@Simplicio](https://boards.straightdope.com/u/Simplicio)\ **Post date:** [August 21, 2010, 3:54pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/8 "2010-08-21T15:54:28Z")
> [@qpw3141](#): > > A more interesting question, IMO, is what evolutionary advantage did having **lighter** skin have confer that caused people who migrated to cooler climes to lose their colour. Humans use sunlight to produce Vitamin D in the upper layers of their skin. In higner latitudes its thought that winters with little sunlight and humans spending as much time inside where its warm led to paler skin being an advantage, since it aids production of the vitamin. Now adays lots of food is artificially fortified with vitamin D, so its not really an issue. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [August 21, 2010, 4:01pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/9 "2010-08-21T16:01:51Z")
I thought it was an urban myth that Negros evolved because of sun exposure? There are deserts all over the world. You have Asians in Mongolia with the Gobi desert. Indians like the Navajo in North America deserts. Arabs in Saudi Arabs. None of these people are black. They do have darker complexions, but aren’t black. ---
**Author:** ![SmithCommaJohn](https://avatars.discourse-cdn.com/v4/letter/s/ecd19e/32.png) [@SmithCommaJohn](https://boards.straightdope.com/u/SmithCommaJohn)\ **Post date:** [August 21, 2010, 4:19pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/10 "2010-08-21T16:19:08Z")
More accurately, white people developed lighter skin because of a lack of sun exposure. ---
**Author:** ![Belowjob2.0](https://avatars.discourse-cdn.com/v4/letter/b/b9e5f3/32.png) [@Belowjob2.0](https://boards.straightdope.com/u/Belowjob2.0)\ **Post date:** [August 21, 2010, 4:26pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/11 "2010-08-21T16:26:08Z")
[http://knol.google.com/k/why-are-europeans-white-e1#](http://knol.google.com/k/why-are-europeans-white-e1#) [http://backintyme.com/essays/item/4](http://backintyme.com/essays/item/4) Probably not. Assuming they can make clothes to cover themselves up, and grow a variety of foods, their infant mortality rate will not increase due to UV derived vitamin deficiency. The Arabs of the Saudi Peninsula are mostly fair skinned in spite of the brutal sun. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [August 21, 2010, 4:26pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/12 "2010-08-21T16:26:48Z")
As a kid I met some older black men that my uncle had hired. They had spent a lifetime in the sun working in the fields. They literally were the color of ebony. Coal black. You don’t see that much any more because so many people work indoors. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [August 21, 2010, 4:54pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/13 "2010-08-21T16:54:17Z")
1. There is a balance between the advantage that paler skin has in allowing adequate Vitamin D production and the disadvantages it has in not only increased rates of skin cancer but also, and maybe more so, in increased light driven destruction of folate, a B vitamin that is involved in blood cell production and protects against neural tube and other defects in embryonic and fetal growth. Probably the folate issue is the more critical one as it has the more direct and more immediate bearing on reproductive success. 2. Skin color actually has actually adapted to dark and to pale and back again in a variety of populations over evolutionary history. Both points are discussed in detail in [this article](http://www.bgsu.edu/departments/chem/faculty/leontis/chem447/PDF_files/Jablonski_skin_color_2000.pdf) (pdf) > [@](#): > > The earliest members of the hominid lineage probably had a mostly > unpigmented or lightly pigmented integument covered with dark > black hair, similar to that of the modern chimpanzee. The evolution > of a naked, darkly pigmented integument occurred early in the > evolution of the genus Homo. A dark epidermis protected sweat > glands from UV-induced injury, thus insuring the integrity of somatic > thermoregulation. Of greater significance to individual reproductive > success was that highly melanized skin protected against UV-induced > photolysis of folate (Branda & Eaton, 1978, Science 201, 625–626; > Jablonski, 1992, Proc. Australas. Soc. Hum. Biol. 5, 455–462, 1999, > Med. Hypotheses 52, 581–582), a metabolite essential for normal > development of the embryonic neural tube (Bower & Stanley, 1989, > The Medical Journal of Australia 150, 613–619; Medical Research > Council Vitamin Research Group, 1991, The Lancet 338, 31–37) and > spermatogenesis (Cosentino et al., 1990, Proc. Natn. Acad. Sci. > U.S.A. 87, 1431–1435; Mathur et al., 1977, Fertility Sterility 28, > 1356–1360). > As hominids migrated outside of the tropics, varying degrees of > depigmentation evolved in order to permit UVB-induced synthesis of > previtamin D3. The lighter color of female skin may be required to > permit synthesis of the relatively higher amounts of vitamin D3 > necessary during pregnancy and lactation. > Skin coloration in humans is adaptive and labile. Skin pigmentation > levels have changed more than once in human evolution. Because of > this, skin coloration is of no value in determining phylogenetic > relationships among modern human groups. 1. The speed of this process may be [faster](http://www.npr.org/templates/story/story.php?storyId=100057939) than you may think. (Same scientist interviewed a few years later on NPR.) > [@](#): > > Skin has changed color in human lineages much faster than scientists had previously supposed, even without intermarriage, Jablonski says. Recent developments in comparative genomics allow scientists to sample the DNA in modern humans. > > By creating genetic “clocks,” scientists can make fairly careful guesses about when particular groups became the color they are today. And with the help of paleontologists and anthropologists, scientists can go further: They can wind the clock back and see what colors these populations were going back tens of thousands of years, says Jablonski. > > She says that for many families on the planet, if we look back only 100 or 200 generations (that’s as few as 2,500 years), “almost all of us were in a different place and we had a different color.” > > Over the last 50,000 years, populations have gone from dark pigmented to lighter skin, and people have also gone the other way, from light skin back to darker skin, she says. > > “People living now in southern parts of India [and Sri Lanka] are extremely darkly pigmented,” Jablonski says. But their great, great ancestors lived much farther north, and when they migrated south, their pigmentation redarkened. > > “There has probably been a redarkening of several groups of humans.” ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [August 21, 2010, 5:37pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/14 "2010-08-21T17:37:18Z")
[QUOTE=Simplicio, but Chronos with the same thought] … Now adays lots of food is artificially fortified with vitamin D, so its not really an issue. [/QUOTE] This statement deserves its own comment. Actually [vitamin D deficiency](http://jn.nutrition.org/cgi/content/abstract/135/2/332) is a significant problem in Northern climes today. And pertinent to issues of evolution, the effect [on mothers and their babies](http://pediatrics.aappublications.org/cgi/content/abstract/125/4/640) is a major issue. > [@](#): > > A high proportion of infants and their mothers in New England were vitamin D deficient. Prenatal vitamins may not contain enough vitamin D to ensure replete status at the time of birth. And it has a variety of consequences beyond bone health, including more kids that [wheeze](http://www.ajcn.org/cgi/content/abstract/85/3/788), and diabetes and cancer risk. Adults in Northern climes, such as [Canada](http://www.cfp.ca/cgi/content/full/53/5/841), but even [Arizona](http://www.cfp.ca/cgi/content/full/53/5/841) have high rates of deficiency. Vitamin D fortification has been insufficient. This [Mayo Proceedings review](http://www.mayoclinicproceedings.com/content/81/3/353.full) makes the case for both taking supplemental Vitamin D and for "sensible suberythemal sun exposure ": > [@](#): > > Vitamin D is important for calcium and phosphorus homeostasis and musculoskeletal health. In children, severe vitamin D deficiency (25[OH]D, \<10 ng/mL [24.9 nmol/L]) manifests as rickets, and vitamin D inadequacy (25[OH]D, 10-29 ng/mL [24.9-72.4 nmol/L]) can impair or retard attainment of peak bone mass. In adults, inadequate vitamin D can result in secondary hyperparathyroidism, decreased BMD, osteoporosis, osteomalacia, and increased risk of fragility fractures.250-252 > > Vitamin D inadequacy is a global problem, especially among elderly patients and patients with osteoporosis. Risk factors for low vitamin D include lack of exposure to sufficient sunlight, inadequate dietary intake and supplementation, and other factors, including obesity, age, medication use, sunscreen use, covering all skin with clothing, and skin pigmentation. Fortunately, vitamin D supplements are widely available and relatively inexpensive. … Many lines of research support the concept that inadequate vitamin D may be involved in the pathogenesis and/or progression of several disorders, including cancer, hypertension, cardiovascular disease, neuromuscular diseases, osteoarthritis, diabetes, and other autoimmune diseases (Table 2). Some of the mechanisms by which vitamin D exerts its noncalcemic effects include apoptosis, anti-angiogenesis, antiproliferation, prodifferentiation, and immunomodulation … > > … Finally, we should not forget the important role that sensible sun exposure has in providing both young and old people with their vitamin D requirement. It is well documented that excessive exposure to sunlight, especially the number of sunburning experiences, is related to increased risk of squamous and basal cell carcinoma.258,259 These skin cancers, if detected early, are usually easily treated and often cured. Melanoma, however, is one of the most aggressive and deadly forms of skin cancer. This is because melanocytes are neurocrest cells and when they become malignant they express the Slug gene, which is responsible for its quick exit from skin metastasizing to various organs, making it difficult to detect and treat.260 However, it should be appreciated that most melanomas occur on the least sun-exposed areas.16,261,262 Furthermore, Kennedy et al259 reported that lifetime sun exposure appeared to be associated with a lower risk of malignant melanoma, despite the fact that lifetime sun exposure did not diminish the number of melanocytic nevi or atypical nevi. Furthermore, Berwick et al263 reported that sun exposure is associated with increased survival in patients with melanoma, and Chang et al264 reported that a history of increased sun exposure was associated with reduced risk of non-Hodgkin lymphoma. These observations are consistent with the suggestion of Apperly163 that sun exposure seems to provide an immunity for most deadly cancers, even though it is associated with increased risk of relatively benign skin cancer. No substantiated scientific evidence exists to suggest that sensible suberythemal sun exposure significantly increases risk of any type of skin cancer and certainly not melanoma. The negative publicity regarding sun exposure during the past 30 years has resulted in a vitamin D deficiency pandemic. The important role that sensible sun exposure has in providing vitamin D for the world’s population needs to be reevaluated. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [August 21, 2010, 5:38pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/15 "2010-08-21T17:38:32Z")
The thing is, this experiment has pretty much been done a number of times (although not with a limited population), and none that I know have turned “black”, even if we just refer to skin color. Could it happen? Of course. Would it happen? Maybe and maybe not. ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [August 21, 2010, 5:57pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/16 "2010-08-21T17:57:33Z")
> [@John\_Mace](#): > > The thing is, this experiment has pretty much been done a number of times (although not with a limited population), and none that I know have turned “black”, even if we just refer to skin color. Could it happen? Of course. Would it happen? Maybe and maybe not. Darker, yes. But I agree, black is unlikely, but possible. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [August 21, 2010, 6:38pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/17 "2010-08-21T18:38:11Z")
All white people of European descent have a particular genetic defect that causes us not to properly produce melanin. Interestingly, lighter skinned people of Asian descent have a defect in a different gene, which means that lighter skin evolved at least twice independently of each other. So, the first question is, are all of your people on Whitey Island of European descent or is it a mix of European and Asian whites? This will make a big difference. In order for black skin to evolve, two things have to happen. First, you have to get your whites to develop a corrected (or at least functioning) version of the gene that regulates the production of melanin. This will be easier if your population is a mix of European and Asian whites, since each has a proper copy of the other’s defective gene. If you don’t have a mix of Europeans and Asians then the only way you’ll get a properly functioning gene is for the malfunctioning gene to mutate into a functioning one, which could take a very long time. The second thing that has to happen is that there has to be some sort of environmental pressure to select for this gene. Just being on an island isn’t enough. Humans make shelter and clothing and can adapt so that the sunlight isn’t an issue. You’d have to make it impossible for your residents to make clothing and shelter so that the direct sunlight would become an issue. Basically, if extreme sunlight isn’t killing your whiteys, they aren’t going to evolve. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [August 21, 2010, 6:43pm UTC](https://boards.straightdope.com/t/would-white-people-stuck-in-an-island-eventually-evolve-to-black/550970/18 "2010-08-21T18:43:20Z")
Define “black”. (And yes, the issue here is skin color alone.) As dark as the majority of “Black” Americans? Well, many in Southern India, especially those who are of the Dalit group (formerly designated as “untouchables”), are darker than that. Depending on what theory of migration into Australia you accept, the Australians aboriginals probably began similar in tone to Asian populations and are darker than the average American Black. [The Vedda](http://en.wikipedia.org/wiki/Vedda_people) of Sri Lanka, darker than that. Heck, many populations indigenous to more equitorial climes, many now gone, have/had skin darker than that. As Black as the darkest African Black? Probably not, at least not unless humans lose their proclivity for clothing and shaded shelter, as noted above…