How Europeans evolved white skin (2015)
sciencemag.org
sciencemag.org
SLC24A5 is an interesting gene - I don't think Vitamin D is the full story. It's an SNP that is alone responsible for 25-40% of skin tone difference between Europeans and West Africans, and is virtually fixed in European populations (99%). However it's also under selection in places like the Ethiopian highlands, where sun exposure is presumably not an issue. Furthermore, if it were just about Vitamin D, you would expect that just about any loss-of-function allele would do. Compare to mutations that confer malaria resistance - there's a whole wikipedia list: https://en.wikipedia.org/wiki/Human_genetic_resistance_to_ma... - why do we not see the same for skin tone variation in Europe? Why is this single point mutation omnipresent, if it's theoretically only lightening the skin so that Vitamin D synthesis is easier?
The original study[1] doesn't suggest a connection between lactase persistence and vitamin D. It does discuss those topics in close proximity, though, which I suspect misled the author of the (popularizing) Science article.
That is the driving force for lighter skin (unless your diet is mostly fish, such as the Inuit). Skin gets darker again when migration towards sunnier climates happens: while UV light is essential for the synthesis of D3, it also destroys folic acid / vitamin B9 [1], which is essential when the neural tube of a fetus is being formed.
And since this mutation is so very visible, maybe here sexual selection plays a role, just like it is suspected with blond hair?
1: https://www.sciencedaily.com/releases/2014/03/140321095240.h...
In Asia, light skin evolved separately and is using different genes.
The Ethiopian highlands have been historically productive in agriculture. Agricultural diets contain less Vitamin D, increasing the selective pressure for lighter skin tones.
The highlands are also cooler than other regions of Africa at similar latitudes, resulting in more clothing being required on average. More clothing necessitates more UVB absorption per unit of skin exposed, which would further select for lighten skin tones.
Cool.
That doesn't make any sense, unless it's reinforced milk contains almost no vitamin D (2 IU per 100g, recommendations are 2500 IU/day for children aged 1~3 to 4000 IU/day for adults). Plus there are lactase persistence clusters outside Europe which make even less sense given the Vitamin D hypothesis (e.g. arabian peninsula, Western Africa).
Lactase persistence overlaps much better with historical pastoralism, which makes a lot more sense: milk is high in calories[0], being able to use these calories when they're available is advantageous. Plus it also provides some fat, proteins and B2, B12 and Calcium micro-nutrients in appreciable quantities (15, 20 and 10% DRI respectively for un-fortified whole milk).
edit: even more so local, small-scale pastoralism: before refrigeration you'd have had to consume the milk within hours so either a few familial animals or a small herd at the tribal/village level. That could also explain why some cultures have a history of dairy products but not of consuming milk directly (and thus low lactase persistence).
[0] cow milk is ~250kJ/100g, and much of that is locked in the ~5g of lactose
A (perhaps pedantic) correction: it's more accurate to say that mutants who were pale-skinned milk drinkers were more successful at surviving and proliferating in Northern Europe, and so the population gained this mutation. Natural selection is not a driven process, it doesn't have an objective; it is, however, a driving process, where it favors one aspect of a population over another.
I think the correct wording is always important when talking about natural selection because these processes are more stochastic then we tend to believe.
So India likely has milk-digesting ability at least in part from the same root as the European milk-digesting ability. But the (Indo-)European mutation doesn't seem to have been the only one: https://www.nature.com/news/archaeology-the-milk-revolution-... Also in Western Africa, as well as in the Arabian Peninsula and Eastern Africa there seem to have been independent mutations.
Furthermore, I was under the impression milk consumption generally spread from the middle east with rudimentary cheese production with rennet, reducing the lactase to an easier to digest level. This might have been after the europeans started their genetic movement, but I don’t believe that culturally the practice of milk consumption originated from Europe. Also, milk consumption has never been directly proportional to genetic disposition to it. Even now milk products can be popular in largely lactose intolerant cultures—maybe the ice cream is worth the farting!
Of course I’d love to be corrected. But you seem to be conflating two or three separate narratives here—this might be how you end up with stuff like Jared Diamond pseudoscience. In particular, I don’t believe Indo European migration was a physical migration of any particular people—and genes typically take a bit longer to move than evidence points to with the Indo European linguistic/cultural migration. This was at one point particularly key in debunking arguments like, say, “the aryan people taught the indians how to speak”. Now of course we have much richer tools at demonstrating both the diversity of known languages and deep roots connecting them, and better narratives to explain them.
But hey, I’ve also made arguments that milk drinking might provide a huge resource advantage in a world where nobody drank it, allowing for economic and reproductive benefit.... maybe the milk drinking did europeans “sprint” east.
Not the case. You're making the "pots, not people" case, which ancient DNA evidence has thoroughly debunked. Changes in material culture usually do indicate large-scale population movements. Yamnaya remains from the Caucuses, for example, are genetically almost identical to the ones buried in the Corded Ware culture that spread through Europe ~5000 years before present. The Yamnaya, a steppe people, completely overran Europe, and today, contribute just over 50% of the ancestry of Western European populations and who spread Indo-European languages there and elsewhere.
The idea that prehistory was full of peace, love, and gradual and voluntary cultural change is ridiculous and indefensible, especially in light of modern genetic evidence, but also on the grounds of common sense.
Why wouldn't you expect to see large scale folk migrations? We have historical records of large-scale movements (e.g., Germanic tribes from Tacitus), and one would expect similar movements, of even greater scope and intensity, to have occurred in prehistory. This kind of movement was the norm, not the exception, in prehistory.
Post-1970s thought in this area seriously annoys me. It presumes a gradual, peaceful transition everywhere at all times despite stark evidence to the contrary. Read Ward-Perkins for a good rant on how fellow historians believe, against all historical and archaeological evidence, that Rome never fell. He's as frustrated and baffled by this thinking as I am.
I wasn’t trying to contradict this, rather that the any genetic migration correlated with a culture/language migration would have likely trailed significantly speed wise and should be demonstrated, not assumed. I am certainly not arguing for a lack of conflict :)
The place of milk in especially early north Indian culture (but continuing into today, esp. say in the Punjab) is not like ice cream parlours in China or whatever. It is quite clear that a large percentage of caloric intake would have been from milk products, and seemingly not primarily cheese, but milk/cream and butter/ghee. The prominence of milk products in India for the last few thousand years is not at all in doubt (and, again, not in the sense of eating the occasional ice cream and farting).
No-one is saying that Indo-Aryan was the first language in India, so I don't know where you're bringing that in from. The Dravidian speakers emigrated into India either around the same time or before the Indo-Aryans, and the Munda speakers seem to have been there earlier than either, and it is quite clear that there was at least one other language family well established in India before the Munda speakers entered (quite possible multiple language families) as attested by the large percentage of words of completely unknown origin in languages like Hindi for agriculture/crops, as well as the languages of the Andaman islands.
So there is some type of link but most likely both came from the Eurasian steppe and have an ancestral link.
This meme will end up being the last causality in a long line of poorly written narratives extrapolated from either poor data, or poorly interpreted data. That is we completely ignore a lot of factors. For example both South Indians, and North Indians are from a same divergent ancestor tens of thousands of years ago.
Another example is the eponymous R1 signature that people use to construct a particular narrative leave out the fact that R1 originated at the very least in Asia. Where exactly scientist have argued anywhere from Central, to South, to East Asia.
A more sane, and logical argument would be that at different points in time people have immigrated to India, and emigrated out of India. And not just India, through Eurasia people have traded genetics, linguistics, and culture with each other for at least 80,000 years.
That is there is not just a single large number of migration from one area to another, but multiple, and in various directions.
But presumably an ancestor shared by lots of other peoples too - I would guess European, North African, Middle Eastern, perhaps as well.
> A more sane, and logical argument would be that at different points in time people have immigrated to India, and emigrated out of India. And not just India, through Eurasia people have traded genetics, linguistics, and culture with each other for at least 80,000 years.
Yes, and in interesting ways. But speaking a language and borrowing words from a language are two different things.
I don't see how any of this argues against the linguistic and sociocultural similarities between subsets of early Europeans and subsets of early Indians which point towards shared ancestry for these two subsets.
I'm not arguing against the similarities, but arguing against a central singular expansion of some group of peoples that just so coincidently called themselves "Aryan". That is there is no evidence for a singular people/civilization that originated the whole "indo-aryans". The only "Aryans" are the Vedic era nobility that has its roots in India/sanskrit.
That is the word "Aryan" is a gross example of extreme racism, prejudice, and cultural appropriate to further a racist model of human history.
[Racists usurping "Aryan" for a different meaning is not what I'm talking about here, in any shape or form.
Edit to add: Yes, extending 'Aryan' to cover any larger entity than Indo-Iranian is not justified, but "Aryan" is not limited to Indic speakers:--- the Iranians certainly used a form of "Aryan" as well: thus derives the name of "Iran" itself: https://en.wikipedia.org/wiki/Iran_(word) ]
]
http://www.huffingtonpost.com/rajiv-malhotra/how-europeans-m...
I look forward to a rebuttal from the Daily Mail.
http://www.thehindu.com/opinion/op-ed/too-early-to-settle-th... has this:
>"With the information currently available, it is difficult to deduce the direction of haplogroup R1a migration either into India or out of India, although the genetic data certainly show that there was migration between the regions. Currently, CSIR-CCMB and Harvard Medical School are investigating a larger number of samples, which will hopefully throw more light on this debate." //
That is in that admixture there is no recent central asian genetics other than the one that was already there in India prior, about 12,000 years ago.
Mechanism unknown, but the mentioned growth factors might be the cause, similar to the increased insulin presence wrt. obesity.
You'd also expect fat people to get more cancer, and native American Hispanic or East Asian descended populations in the US to get less than the US average. This is what happens.
Of course there are a million other factors and all cancers are different, but in the general case you can guess the relative cancer occurrence between populations with a guess at the difference in their mean volumes.
This won't keep people from trying to sell you a diet, though. Cancer is terrifying, and the idea that we can control it makes us relax. If you eat very little food, especially in childhood when you need calories to grow, you will get less cancer.
Regarding skin tones: What often registers simply as 'black' or 'Asian' from a predominantly white perspective comprises a wide variety of phenotypes and backgrounds, just as there's considerable variation in how white people from different regions or countries look.
The same flood of people moved into Europe, the Indian subcontinent and Persia around the same time, bringing genes, language, religion etc with them.
(They presumably went elsewhere too with less success.)
> Maybe I'm reading this wrong but how does this explain the colour difference between black people and Asian people?
It doesn't; you're reading the summary title correctly but that doesn't reflect what the study actually says.
The study finds evidence that the general european population acquired a light skin and some other traits due to an influx of people carrying a bunch of genetic, linguistic and cultural traits who arrived about 4500 years ago. (Some of those same people are believed to have also headed around the same time in India and Persia, among other places). The study notes that there were already light skinned people in scandinavia around the same time.
So it doesn't explain "how", just points out evidence that most European dwellers (including those in the British Isles) were dark skinned until fairly recently, unlike the dioramas one finds in museums.
"presumed"??!!
I've always thought there was some scientific evidence for this and not mere presumption. Is there not some evidence about the skin coloration of our African ancestors of different periods?
Much of what we know about pre-history is educated guesses based on a tiny amount of evidence and a lot of critical thinking.
In evolution, sometimes a mutation will take away the ability to synthesize a vitamin. If the organism gets enough of it from diet, this is not disadvantageous and won't be selected out.
Vitamin D deficiency is present in all primates. So that give you some notion of how long ago the synthesis was lost.
Vitamin C is similar since it is readily available in fresh meat and many plants. It is absent in Haplorhini (the dry-nosed primates).
It's very nearly a caste system- you can be born next door, speak the same language, eat the same food, think the same way, and you will be treated differently based on racial judgements. That's quite different from "we Hill People hate the River Folk and always will!"
The modern notions of race come from a specific historical moment: the invention of the African slave trade by Western European powers. If the slave trade had not happened, ideas about race would probably be radically different. Chattel slavery on an industrial scale was a new idea and its echoes will probably always be with us.
Caste systems are nearly as much an anthropological universal (at least for civilizations) as the suspicion of outsiders that the OP mentions. Across the world you can find examples of two neighbours brought up in virtually identical conditions, but with restrictions on one due to ancestry.
Racial categories mean that a white American can feel more common ground with a white Russian than his black American neighbor. American white nationalist fellow-feeling toward Russian nationalists suggests to me that it's not really about suspicion of outsiders. Racial categories cut across borders, ancestry, language, and culture.
Feeling confident that one can judge what category someone is in on sight without seeing their clothes, hearing them speak, learning their name, or knowing their ancestry is maybe not quite unique to modern racial ideas, but it certainly makes it stand out.
It's important to add that the definition of 'other' changes. In the U.S., Protestants and Catholics, Italians and Irish used to riot against each other. 'No Irish Need Apply' was appended to job postings. Jews faced significant discrimination.
Sometime around the 1930s, it shifted so that all Protestants became 'white'. Since then, all white-skinned people, including Jews, Mormons, Catholics, became 'white', generally one ethnic group. Nobody seemed to care that Mitt Romney was Mormon; none seem to care or even notice that the US Supreme Court has no Protestants (unless Gorsuch is one).
I take exception even with your examples. How long has there been an "Italy"? In one sense, since the current state emerged in 1861. In another, Italia would only have meant land south of the Rubicon, excluding northern Italy. In another still, it's probably some Etruscan word with some completely different meaning. (Just a guess, I have not looked it up.)
So when you go all the way back to when Europeans adapted for lighter skin and before... There is no "Italy". Maybe even there isn't any "Europe". I think the people answering my comment with "but it's always been us vs them" are really grasping for some cynicism to make themselves feel superior, because I would ask, who exactly is the us or the them they are talking about? Because no current group existed. It is constantly changing. That is the whole point.
(I'm responding to it shifted so that all Protestants became 'white'. which could just be an accidental misphrasing)
One supposed exchange from over 2,500 years ago: https://tricycle.org/trikedaily/buddha-talks-brahmin-suprema...
Of course not, but that's a binary distinction - there 0 'duality' or there is >0 duality. There is a big difference in civil rights, integration, etc. between now and 200 years ago.
Far of "the other" has existed about as long as humans.
;)