
How Europeans evolved white skin (2015) - pulisse
http://www.sciencemag.org/news/2015/04/how-europeans-evolved-white-skin
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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...](https://en.wikipedia.org/wiki/Human_genetic_resistance_to_malaria)
\- 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?

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lordnacho
What's the story with East Asians? They have light skin as well, right? Is it
the same mutation?

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z2210558
No it's different, and thought to have evolved independently. See e.g.
[http://journals.plos.org/plosgenetics/article?id=10.1371/jou...](http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1000867)

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alejohausner
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.

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TrisMcC
Naturally, milk only contains trace amounts of vitamin D. I don't think
ancient humans were fortifying their milk.

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op00to
Wouldn’t cheese be concentrating the vitamins in milk, sort of fortifying it
in as much as it’s making it easier to consume the amounts of milk you need
for vitamin d?

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amriksohata
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 this explain the colour difference between
black people and Asian people? Some black people are very dark compared to
other black people but from the same areas

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_emacsomancer_
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-...](https://www.nature.com/news/archaeology-the-milk-
revolution-1.13471) Also in Western Africa, as well as in the Arabian
Peninsula and Eastern Africa there seem to have been independent mutations.

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drb91
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.

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quotemstr
> Just to be clear, the Indo European migration is presumed to be a
> trade/culture migration

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.

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_emacsomancer_
Though, at the same time, some of the overly racialised interpretations of the
19th-century have been shown to be rather off track. There was a picture
painted of pale-skinned Sanskrit speakers sweeping into India on chariots and
dominating and slaughtering dark-skinned Dravidians (and others). That does
not seem well supported. The Indo-Aryan speakers certainly were warlike, but
the battles narrated in the Rgveda involved Indo-Aryans on both sides, allied
with non-Indo-Aryan speakers on both sides; as well as people with overtly
non-Indo-Aryan names sponsoring rituals in the Rgveda. (None of this goes
against your primary point. And certainly we know of plenty of militaristic
invasions of India in more recent times, including the Mughals.)

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giardini
I was surprised to see the article state _" The modern humans who came out of
Africa to originally settle Europe about 40,000 years are_ presumed _to have
had dark skin, which is advantageous in sunny latitudes. "_

"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?

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freehunter
To say the least, it's kind of difficult to scientifically prove the skin
color of someone from 40,000 years ago. Fossilized bones don't tell you if
someone was black or white or whatever. We're not even entirely sure what skin
color ancient Egyptians had.

Much of what we know about pre-history is educated guesses based on a tiny
amount of evidence and a lot of critical thinking.

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amelius
Why did we evolve to rely on vitamin D in the first place? It's a hormonal
substance, and doesn't carry any energy by itself, so why do we need it so
badly?

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cjensen
Short answer it is needed for a few things in all animals, so a source is
needed. Most animals can synthesize it.

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).

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asveikau
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 a crazy person trying to impose them. And yet
all people wanted to do on that thread was talk about present differences.

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irrational
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 might be language, it might be religion, it
might be you live in the mountains and we live in the valley, you are a herder
and we are farmers, you are rural and we are urban, you have curly hair and we
have straight hair, etc. ad naseum.

~~~
roywiggins
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.

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Mediterraneo10
"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.

~~~
roywiggins
One difference from a caste system- foreigners are assigned the same racial
categories as locals, whereas if I visited a society with a caste system, I
simply wouldn't have a caste, at least not by default. Black Africans in
America are considered the same race as black Americans, regardless of sharing
absolutely no recent ancestry whatsoever, and white Africans are the same race
as white Americans, again without sharing any meaningful recent ancestry. A
white Hispanic person will be treated as white (see: Ted Cruz) but a black one
will be treated as black, even if they're literally siblings.

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.

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macawfish
Do you know what's giving a lot of people white skin these days? Racialized
selective breeding.

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ada1981
Dairy Industry Astroturfing?

;)

