What the shades of humanity should be

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From Geographic distribution of environmental factors influencing human skin coloration:

…The UVR [ultraviolet radiation] data recorded by satellite were combined with environmental variables and data on human skin reflectance in a geographic information system (GIS). These were then analyzed visually and statistically through exploratory data analysis, correlation analysis, principal components analysis, least-squares regression analysis, and nonlinear techniques. The main finding of this study was that the evolution of skin reflectance could be almost fully modeled as a linear effect of UVR in the autumn alone. This linear model needs only minor modification, by the introduction of terms for the maximum amount of UVR, and for summer precipitation and winter precipitation, to account for almost all the variation in skin reflectance…..

The map above was generated from the regression analysis. Apparently it has been updated as of 2007 (received the link from a friend). It does look much better than it did in the original paper (which I have read and have a PDF copy of). Do note that the selection of peoples whose reflectance values were plugged into the model obviously matters. But I still think it’s interesting the sort of predictions this map produces and how it fits with our intuitions of what the distributions should be, and the knowledge of what they are. Note the equivalent latitudes in Europe and North America, or Australia.

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39 Comments

  1. It would be interesting to take into account ancient population sizes too. That is, a large population would tend to bleed into a small population, but not the other way around.

  2. For example, I wouldn’t expect the tiny strip of Mediterranean-level UVR in southern Africa to have much of an evolutionary impact.

  3. For example, I wouldn’t expect the tiny strip of Mediterranean-level UVR in southern Africa to have much of an evolutionary impact. 
     
    you mean that it’s cut off from other areas which might benefit from its loss of function mutations? like, it isn’t a hotspot. right, that’s why i’m interested in population substructure and what not….

  4. Here’s an interesting WaPo article that’s not exactly on topic but periphreal and related to other discussions that have been on the subject here. 
     
    In India’s huge marketplace, fair skin sells-  
    White faces, mostly from Eastern Europe, dominate advertising” 
     
    http://www.msnbc.msn.com/id/22865130/ 
     
    snip ***** 
     
    “Indians have a longing for that pure, beautiful white skin. It is too deep-rooted in our psyche,” said Enakshi Chakraborty, who heads Eskimo India, a modeling agency that brings East European models here. “Advertisers for international as well as Indian brands call me and say, ‘We are looking for a gori [Hindi for white] model with dark hair.’ Some ask, ‘Do you have white girls who are Indian-looking?’ They want white girls who suit the Indian palate.” 
     
    Indians’ color fixation is also evident in classified newspaper ads and on Web sites that help arrange marriages. The descriptive terms used for skin color run the gamut: “very fair,” “fair,” “wheat-ish,” “wheat-ish-medium,” “wheat-ish-dark,” “dark” and “very dark.”

  5. Most of the US and quite a bit of Canada are Mediterranean, not Northern European.

  6. Just to add that cold weather and low sunlight don’t correlate well. Minnesota and Canada are colder than Norway and Sweden but have more sunlight. (Continental vs. maritime climates.) 
     
    The average January temperature in Minneapolis (13 F) is 3 degrees colder than in Moscow (16 F). Winnipeg is the coldest city of its size in the world, except for Ulan Bator.

  7. (Continental vs. maritime climates.) 
     
    I see Finland looks just like Norway. I seem to recall the ultraviolet mostly passes thru clouds.

  8. … Eskimo India, a modeling agency that brings East European models [to India] … 
     
    God only knows where they came up with that name!

  9. Tasmania, in particular. I had thought the Tasmanians had been marooned there for 40,000 years or more. Why weren’t they paler? 
     
    Maybe lighter-skinned births were treated as cursed or bastards in that conservative / primitive culture?

  10. The Americas are very much skewed by the late arrival of humans to these shores. 
     
    That map delivers best in South Africa. The Bushmen are indeed lighter than the later-arriving Zulus. 
     
    I’d say the map should be used as a baseline for estimating the rate of genetic drift per location (and therefore time of arrival).

  11. Tasmania, in particular. I had thought the Tasmanians had been marooned there for 40,000 years or more. Why weren’t they paler? 
     
    well, 10,000 years from the mainland.

  12. Wouldn’t it make more sense to look at UVR values around the time when selection for skin colour took place: i.e. the neolithic?  
    It would also be fitting to take into account the time when present indigenous people migrated to those areas. 
    Because the skin colour distribution as it is pictured in the map does not really show actual pigmentation, as some readers have pointed out, not only in the Americas and Australia, but also in Europe.

  13. RE: Tasmania 
     
    Tasmania has lots of sunshine, despite chilly winters they didn’t wear a lot of clothes, and I don’t know about that satellite data, we have a lot of UV in summer, UV warning on weather forecasts are very common, we are at the same lattitude as northern Spain/ Oregon. The east coast is not very cloudy and in a rain shadow. 
     
    I doubt mutations dropping melanin would prosper. 
     
    Tomorrow’s UV Index: 7 [High] UV Alert from 9:50 to 17:00 
     
    (that link is an dynamic page so don’t expect it to say that tomorrow about the day after…) 
    Indigenous Tasmanians were darker than mainland Aboriginals at time of ‘white’ settlement. Thought to represent orginal populations moving out from Africa along the Indian Ocean coasts.

  14. In India’s huge marketplace, fair skin sells-  
     
    Preference for fair skinned females in their respective castes has been prevalent for long. However, it is the males who have started buying fairness creams now.(more likely because of adverts) 
     
    There are no mention of “White Skin” as ideal colour in the Hindu texts. But the mention of “Golden Hues” finds mention even in Vedas. 
     
    Thus northern middle east,viz Iranian, Armenian complexion with fair colour and dark hair might be the preferred complexion rather than “white”. Such individuals are found even in deep south India. 
     
    It is interesting to note that many Hindu gods, Rama, Krishna and the great Sage Vyasa are dark skinned.

  15. >>”In India’s huge marketplace, fair skin sells”. 
     
    About 40% of mtdna from NW India seems to be of ‘recent’ Middle Eastern/Med origin with high frequency in a coastal pocket in the south (Roman Trade ?,see Kivilslid papers for data)

  16. >>God only knows where they came up with that name. 
     
    Assuming the agency as no connection with the European agency of the similar name,I assume its psychology.The idea of the Eskimo gives the sense of, coolness which may aid memory.”I need a model for my campaign,I”ll cool Eskimo.”,(the fashion designer remembers because when she heard the name she was in a taxi in the middle of the Delhi rush hour with temperatures of 40 C,the name gave here sense of escape,ice fields, coolness).Thats why NPL ,Hypnosis etc may work.The use of language may change behavior, thats why for instance kids in private schools seem to behave better than public schools ,due to their use of language.Or the kids could be hypnotized e.g George Bush ,Tony Blair :) 
     
    Religions e.g Hindus ,Scientologists,Freemasons and even increasingly Christian groups have known how language (e.g mantras) effect mental states.One can argue all the religious leaders were/are hypnotists.

  17. >>>>God only knows where they came up with that name. 
     
    It seems the Indian agency is connected to Eskimo Europe.Interesting that if one checks out the models on Eskimo.is (for scientific purpose only) one can see further one goes south the softer the jaw line.Is their a connection with jaw line and skin colour ?

  18. I think I’ve just answered my own question.Further North one goes the more reliance there is on meat eating (lighter skin) further south one goes the more varied the diet (darker skin).One could argue further north one went the greater need for big jaws (to munch all that meat/bones),skin color selection was only secondary.I wonder if Northern Europeans with smaller jaws have lighter skin than other Northerners,due to the fact they could not extract the vitamin D from munching animal bones.A theory,any takers?

  19. Absolute distance from the equator and cranial capacity: 
     
    r = +.62 (p < 10) 
     
    cranial capacity = 2.5 cm3 × degrees latitude + 1257.3 cm3 
     
    [Beals K. L., Smith C. & Dodd S. M. (1984). "Brain size, cranial morphology, climate, and time machines". Current Anthropology, 25, 301-318.] 
    —- 
     
    skin color to winter high temperature  
    r = .85 (p < 0.001) 
     
    IQ to skin color  
    r = – .92 (p < 0.001) 
     
    [Templer, D. I. and Arikawa, H. (2006). Temperature, skin color, per capita income, and IQ: An international perspective. Intelligence, 34, 121-139]

  20. (Mods: please delete my previous posts) 
     
    Jaspa: About 40% of mtdna from NW India seems to be of ‘recent’ Middle Eastern/Med origin 
     
    Are you sure? From Kivisild’s PhD thesis (2000, p.29): Both East and West Eurasian specific haplogroups in Indians are represented by deep Indian-specific branches. The primary clustering of mtDNA lineages is not language-specific (Hindi, Dravidic) and only a small fraction of Indian mtDNA lineages (less than 10%) can be ascribed to a relatively recent admixture with western Eurasians … An attempt to date their arrival was made that yielded an estimate of about 9,000 years. This date, however, is most likely an average of a number of different West Eurasian donations to the Indian gene pool.As for the social aspects of skin colour, although there is strong preference for fairer skin throughout South Asia, we should remember that the “palest” South Asian group (the Pashtuns/Pathans) is generally regarded as “low-status” by other local populations (at least that’s what I’m getting from one Punjabi source…)  
     
    vantage: does this interesting (ahem) study include the notoriously dark-skinned, though historically advanced Tamils?

  21. toto, the frequency in the punjab is quite a bit higher than the rest of south asia. on average punjabis are still more similar to other south asians than they are to persians, for example, but they have a lot more west eurasian lineages than other south asian groups (the frequency varies by study and how they assign the lineage). 
     
     
    vantage: does this interesting (ahem) study include the notoriously dark-skinned, though historically advanced Tamils?
     
     
    we’ve gone over this. the correlation between skin color & IQ can’t be connected to a common causal factor. there were 4-5 QTLs of very large effect for skin color trait value, no large known QLTs for IQ.

  22.  
     
    Tasmania has lots of sunshine, despite chilly winters they didn’t wear a lot of clothes, and I don’t know about that satellite data, we have a lot of UV in summer, UV warning on weather forecasts are very common, we are at the same lattitude as northern Spain/ Oregon. The east coast is not very cloudy and in a rain shadow.
     
     
    I doubt mutations dropping melanin would prosper. 
     
     
    this is an important point, but 
     
    1) melanin dropping mutations did prosper at equivalent latitudes in east asia and europe. compare the typical spaniard or algerian to a photo of a tasmanian. i really doubt that tasmania is sunnier than algeria. 
     
    2) the UV warnings, isn’t part of this due to the ozone depletion in the antarctic? 
     
    3) the population of northern europeans who settled in australia are very depigmented for the latituded.

  23. Er Vantage, are you saying I’m poor as well as dump,or is it the other way around :)

  24. can we not turn this into a discussion about IQ? pretty soon no one will be talking about anything else….

  25. The way to stop the boys discussing IQ, Razza, is to get ‘em talking about “hotties”.

  26. Razib’s 
     
    “2) the UV warnings, isn’t part of this due to the ozone depletion in the antarctic?” 
     
    The Ozone Hole is a looonnngggg way south of here. It’s just all water, like from Oregon/Spain to the North pole being all water. World maps don’t emphasize this much. 
     
    “3) the population of northern europeans who settled in australia are very depigmented for the latituded.” 
     
    Not sure what you mean. The genes for lots of melanin in Tasmanian Aboriginal populations are rgarded as recessive, but I have no knowledge of studies backing that up.

  27. Razib’s “i really doubt that tasmania is sunnier than algeria.” 
     
    Maybe not but it could be sunnier than Spain, (particularly on the east coast, the west is very very wet, but humans tend to avoid it even today)which is not too far from Algeria. 
     
    I don’t doubt the tropics get more sun. But we have “excellent weather” here generally. 
     
    Don’t tell anyone though. We have enough tourists as it is.

  28. As I understand, amount of sunshine is almost purely dependent on latitude for these purposes, because UV radiation passes through clouds. Whereas other factors (continental climate) affect temperature.

  29. John, there’s much more to it than that. People on highlands will have much less atmosphere on them than northern Europeans (all northern Europeans except Saamis have traditionally lived barely above sea level). Then there’s terrain: people in mountain valleys might actually get less radiation than expected by height. Then there’s vegetation: living in the forest means spending much more time in the shade than you’d do if you lived on the savannah or the tundra and so on. 
     
    The most notable deviation from UV expected based on latitude is probably the Tibetan plateau.

  30. I don’t recall any of the native Amerindian groups being especially dark, even those that lived in the Equatorial regions or high in the Andes. 
     
    What about the claim that skin melanin is a way to cope with certain kinds of parasitism?

  31. Could it be said that those with a middling skin color (Mediterranean) have a fitness advantage in the globalized world, since they can more comfortably withstand both cold and equatorial climates?

  32. Not sure what you mean. The genes for lots of melanin in Tasmanian Aboriginal populations are rgarded as recessive, but I have no knowledge of studies backing that up. 
     
    i doubt they were recessive. most of the studies coming out in the past 5 years in genomics show that skin color genes exhibit additivity (there is some data on locus which shows dominance for light skin, KITLG). tasmanians could have been recessive of course, but i don’t know any pedigree studies (seeing as they went extinct before these sorts of researchers were common!). just google ‘skin color’ on the search box to the right, i’ve blogged this before a lot. 
     
    Maybe not but it could be sunnier than Spain, (particularly on the east coast, the west is very very wet, but humans tend to avoid it even today)which is not too far from Algeria. 
     
    look, there’s no reason for all this speculation, OK? you can look these things up! “The evolution of human skin coloration,” jablonski & chaplin. google it and look at page 11 (you can find a PDF online). tasmania is like the mediterranean on the map. that makes sense from what i know of the rainshadow on much of the island. 
     
    What about the claim that skin melanin is a way to cope with certain kinds of parasitism? 
     
    i already made the claim. i’ll update when i have more data, right now it’s a conjecture…. 
     
    Could it be said that those with a middling skin color (Mediterranean) have a fitness advantage in the globalized world, since they can more comfortably withstand both cold and equatorial climates? 
     
    …perhaps, but 
     
    1) olive skinned people have problems with vitamin D deficiency up north. 
     
    2) many northern europeans can tan facultatively too. i don’t know if the olive-skinned advantage is big enough here (i.e., how many extra hours before folate destruction does it give you?).

  33. Jaakeli, good point. I was just trying to point out that cloud cover is fairly irrelevant, and that temperature is not coordinated with sun exposure.

  34. many northern europeans can tan facultatively too 
     
    Yeah, what about tanning? Why didn’t we develop better tanning ability instead of fixed skin color? After all, we do tan to some degree. 
     
    Probably because humans didn’t move around all that much…

  35. are the indians near the west coast of south america really that dark, or is that a problem with the graphic?

  36. darren 
     
    1) this is a projection based on a model generated from a fit of the empirical data. so no, they’re not that dark. they should be as dark as africans, but they aren’t (it’s a relative scale, so no comment on absolute “how dark should someone be at the equator”). 
     
    2) the natives of the high andes are i think the darkest numerous indigenous people in the new world though. UV + relatively sunny climate.

  37. Has anyone considered that the Tasmanian population was extremely small, perhaps fewer than 5000 individuals by the time europeans arrived, divided into even smaller clans with limited intermarriage? Perhaps it could be that the necessary mutations to change their skin color didn’t pop up on demand, and the alleles for dark skin were fixed. Also, the founding population was probably rather small, so it could be a bottleneck which just didn’t let in any of the recessive genes floating around. 
     
    Finally, what about diet? 
     
    I don’t really know, these are things to think about.

  38. Perhaps it could be that the necessary mutations to change their skin color didn’t pop up on demand, and the alleles for dark skin were fixed. Also, the founding population was probably rather small, so it could be a bottleneck which just didn’t let in any of the recessive genes floating around. 
     
    1) as i said above, the genes for light skin aren’t recessive. in fact, one of them KITLG is dominant (i don’t really believe that this’ll hold up, but whateva). 
     
    2) right, the small population size means less variation for selection to work with. totally plausible. 
     
    3) but loss of function mutations are pretty easy to come by. so the barrier is lower because of that. 
     
    4) i know that tasmanians turned away from marine life and forgot how to make hooks or something by the end of their time on the island.

  39. 4) i know that tasmanians turned away from marine life and forgot how to make hooks or something by the end of their time on the island. 
     
    They stoppped eating scalefish about 4000 years ago, it was probably gender political, as they still dive for crayfish, muttonfish (abalone), and other shellfish. Men did not go in the water, were not allowed to, they probably had an islandwide taboo on scale fish and ‘forgot’ how to make fishhooks after they stopped eating them, but whatever the reason for the loss, such islands do not receive new tech as there is no trade or population movements to replace what is lost ( to repeat, for whatever reasons – death of an elder, religious nuttery, cultural practice). 
     
    Gender political? The food was gathered from the sea and fishing always seems to be more like hunting in hunter-gather societies, for some reason men were no longer allowed/wanted to go in the water (it’s too bloody cold if you ask me). 
     
    Lizards big and small in central Australia are “gathered” and even though they are the other white meat this food source is not categorized as hunted. 
     
    I could go on as to why but I won’t just yet.

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