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How Europeans evolved white skin (2015)

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Re: How Europeans evolved white skin (2015)

#21

Post by defen »

Milk does not naturally contain very much vitamin D, so that's a silly reason to expect lactase persistence to have evolved. A much simpler explanation is that it massively increases the calories available to pastoralist populations.

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?

Re: How Europeans evolved white skin (2015)

#22

Post by _emacsomancer_ »

amriksohata wrote: post #4

I'm struggling to understand this, tallness? Didn't that only happen to some European countries in the past hundred years? Because of diet? The ability to digest milk? The Hindu civilisation is one of the oldest in the world and milk and cows are very much a first class thing, suggesting it's not jsut Europeans that could digest milk, but other culture for a very long time. Maybe I'm reading this wrong but how does t…

Some of this is tricky to untangle, because it's easy to intentionally or unintentionally conflate genetics/race, culture, and language, but at least culturally/linguistically the people of North India are related to the majority of the peoples of Europe. So Sanskrit, Hindi/Urdu, Bengali, Gujarati, Punjabi, Kashmiri, Assamese, Nepali etc. are all Indo-European languages, as are Latin, Greek, Russian, Danish, Icelandic, English, Welsh etc. Comparison of early Indo-European texts strongly suggest that the first classness of cows/milk in India is a feature of (early) Indo-European cultures more generally. Indian skin colour shows a great deal of variation, including very pale and very dark and points inbetween. Which presumably correlates in part to the India having experienced a large number of migrations over a fairly long period of time.

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.

Re: How Europeans evolved white skin (2015)

#23

Post by masklinn »

alejohausner wrote: post #3

So vitamin D is the driving factor: either you lose melanin, or become lactose tolerant, or you die. With dark skin, you can't make enough D from sunlight. If you can't drink milk, you can't get it from diet. Either way, ancient Northern Europeans had to mutate into pale-skinned milk drinkers, because their land is not very sunny. Cool.

> So vitamin D is the driving factor: either you lose melanin, or become lactose tolerant

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

Re: How Europeans evolved white skin (2015)

#24

Post by roywiggins »

irrational wrote: post #20
asveikau wrote: post #5

People are so hopelessly confused about race. I recently made the mistake of reading Facebook comments on a widely shared public post of an article not unlike this one. And... So many comments attempting to graft our contemporary divisions and yes, racism, onto a story like this. It's pretty simple to think that so many years ago, the distinctions were simply not there, to the extent where you would have seemed like…

You might want to read some introductory anthropology textbooks. For as long as there have been humans it has been us against them. Them/the others/the strangers/the not us are dangerous and cannot be trusted. There are specific rituals that an other must go through to become a part of the community - the means by which one of the others can become one of us. What separates us from them? It might be skin color, it mi…

You're not wrong, but it's worth saying that contemporary racism is qualitatively quite different from, say, Greek ideas about their own superiority or tribal conflicts generally.

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.

Re: How Europeans evolved white skin (2015)

#25

Post by sctb »

Arnt wrote: post #6
amriksohata wrote: post #4

I'm struggling to understand this, tallness? Didn't that only happen to some European countries in the past hundred years? Because of diet? The ability to digest milk? The Hindu civilisation is one of the oldest in the world and milk and cows are very much a first class thing, suggesting it's not jsut Europeans that could digest milk, but other culture for a very long time. Maybe I'm reading this wrong but how does t…

WARNING! GROSS OVERSIMPLIFICATION: Potential for tallness is genetic. How much individuals realise of that potential is a matter of childhood diet and health, which has grown very good in Europe during the last 5-10 generations.

> Please don't use uppercase for emphasis.

https://news.ycombinator.com/newsguidelines.html

Re: How Europeans evolved white skin (2015)

#26

Post by amriksohata »

_emacsomancer_ wrote: post #22
amriksohata wrote: post #4

I'm struggling to understand this, tallness? Didn't that only happen to some European countries in the past hundred years? Because of diet? The ability to digest milk? The Hindu civilisation is one of the oldest in the world and milk and cows are very much a first class thing, suggesting it's not jsut Europeans that could digest milk, but other culture for a very long time. Maybe I'm reading this wrong but how does t…

Some of this is tricky to untangle, because it's easy to intentionally or unintentionally conflate genetics/race, culture, and language, but at least culturally/linguistically the people of North India are related to the majority of the peoples of Europe. So Sanskrit, Hindi/Urdu, Bengali, Gujarati, Punjabi, Kashmiri, Assamese, Nepali etc. are all Indo-European languages, as are Latin, Greek, Russian, Danish, Icelandi…

Are you referring to the Aryan invasion theory? If so that's been debunked a long time ago

Re: How Europeans evolved white skin (2015)

#27

Post by drb91 »

_emacsomancer_ wrote: post #22
amriksohata wrote: post #4

I'm struggling to understand this, tallness? Didn't that only happen to some European countries in the past hundred years? Because of diet? The ability to digest milk? The Hindu civilisation is one of the oldest in the world and milk and cows are very much a first class thing, suggesting it's not jsut Europeans that could digest milk, but other culture for a very long time. Maybe I'm reading this wrong but how does t…

Some of this is tricky to untangle, because it's easy to intentionally or unintentionally conflate genetics/race, culture, and language, but at least culturally/linguistically the people of North India are related to the majority of the peoples of Europe. So Sanskrit, Hindi/Urdu, Bengali, Gujarati, Punjabi, Kashmiri, Assamese, Nepali etc. are all Indo-European languages, as are Latin, Greek, Russian, Danish, Icelandi…

Just to be clear, the Indo European migration is presumed to be a trade/culture migration—there’s not a lot (any?) evidence that this resulted in much increased genetic transfer.

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.

Re: How Europeans evolved white skin (2015)

#28

Post by pulisse »

defen wrote: post #21

Milk does not naturally contain very much vitamin D, so that's a silly reason to expect lactase persistence to have evolved. A much simpler explanation is that it massively increases the calories available to pastoralist populations. 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,…

Milk does not naturally contain very much vitamin D, so that's a silly reason to expect lactase persistence to have evolved.

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.

[1] https://www.biorxiv.org/content/early/2015/10/10/016477

Re: How Europeans evolved white skin (2015)

#29

Post by Mediterraneo10 »

roywiggins wrote: post #24
irrational wrote: post #20

Earlier quoted context omitted.

You might want to read some introductory anthropology textbooks. For as long as there have been humans it has been us against them. Them/the others/the strangers/the not us are dangerous and cannot be trusted. There are specific rituals that an other must go through to become a part of the community - the means by which one of the others can become one of us. What separates us from them? It might be skin color, it mi…

You're not wrong, but it's worth saying that contemporary racism is qualitatively quite different from, say, Greek ideas about their own superiority or tribal conflicts generally. 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…

"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."

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.

Re: How Europeans evolved white skin (2015)

#30

Post by zeotroph »

scythe wrote: post #12
amriksohata wrote: post #4

I'm struggling to understand this, tallness? Didn't that only happen to some European countries in the past hundred years? Because of diet? The ability to digest milk? The Hindu civilisation is one of the oldest in the world and milk and cows are very much a first class thing, suggesting it's not jsut Europeans that could digest milk, but other culture for a very long time. Maybe I'm reading this wrong but how does t…

It's not dairy alone that causes height gain. High dietary protein correlates with production of IGF-1 which correlates with bone growth. Casein stimulates IGF-1 production somewhat more than other proteins, but not by much. Indians eat a relatively low-protein diet due to the prevalence of vegetarianism and not actually that much dairy; most of it is fermented, which, IIRC, deactivates casein.

And, as a side note, height correlates with cancer risk "Its results found that for every extra 10cm (4in) of height, when fully grown, the risk of developing cancer increased by 18% in women and 11% in men.": https://www.bbc.com/news/health-34414446

Mechanism unknown, but the mentioned growth factors might be the cause, similar to the increased insulin presence wrt. obesity.

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