13 ms·

How Europeans evolved white skin (2015)

142 points by pulisse 9y ago

erikb 9y ago
Haha! There you have it social justice fighters. Getting our privilege was hard work! We earned it! (it's a joke in case someone is unsure about it)
alejohausner 9y ago
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.
- trhway 9y ago
  Milk is calcium. Colder climate - bigger body. That needs calcium. Thus milk and vitamin D, both are necessary. Thus pale skin and lactose. Either alone isn't enough.
- TrisMcC 9y ago
  Naturally, milk only contains trace amounts of vitamin D. I don't think ancient humans were fortifying their milk.
  - op00to 9y ago
    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?
- scythe 9y ago
  Milk does not naturally contain vitamin D; fish, mushrooms, and egg yolks are the only natural sources, but the mushrooms have to be exposed to sunlight (which is unlikely; they grow in the shade) and nobody eats that many eggs, so only pescetarian cultures retain darker skin at northern latitudes.
- badosu 9y ago
  The study also points out that there's evidence for sexual selection as well.
- masklinn 9y ago
  > 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
- gumby 9y ago
  If you click on the study you'll see that this point is really an artifact of the summary article, not the actual study.
- deviationblue 9y ago
  > Either way, ancient Northern Europeans had to mutate into pale-skinned milk drinkers, because their land is not very sunny. 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.
  - baddox 9y ago
    This seems like an over-application of the (valid) claim that evolution doesn’t have any specific objective. The sentence you quote doesn’t describe an objective. It only describes a necessity.
- taysic 9y ago
  It is worth noting that some of the people migrating into Europe introducing some of the white skin genes were not from northern regions.
amriksohata 9y ago
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
- Arnt 9y ago
  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.
  - sctb 9y ago
    > Please don't use uppercase for emphasis. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
- bonzini 9y ago
  Europeans are not a homogeneous group with respect to height; for example the Dutch tend to be taller than the Italians. According to the article, even though average height did increase recently, some disposition and possibly some difference was already there in the genes of people from different parts of Europe.
- selimthegrim 9y ago
  Many Indians and people of Indian descent (myself included) are in fact lactose intolerant, hence the prevalence of cheese and yogurt products.
  - primaryobjects 9y ago
    Cheese and yogurt both have lactose.
asveikau 9y ago
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.
- avtar 9y ago
  Race, religion, nationalism, social status, me vs. you.. we’ve been at this for ages. Has there really been a point in time where the human collective consciousness hasn’t involved a sense of duality? One supposed exchange from over 2,500 years ago: https://tricycle.org/trikedaily/buddha-talks-brahmin-supremacist/ https://tricycle.org/trikedaily/buddha-talks-brahmin-suprema...
  - forapurpose 9y ago
    > Has there really been a point in time where the human collective consciousness hasn’t involved a sense of duality? 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.
- deadbunny 9y ago
  > 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. Far of "the other" has existed about as long as humans.
- irrational 9y ago
  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.
giardini 9y ago
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?
- Profragile 9y ago
  No, because there is NO WAY Europeans came directly from Africans. There is no similarity, no common language, nothing to suggest that there was a close relationship between Africans and Europeans. On the other hand, Europeans have much more similarity with certain Arabic tribes.
- freehunter 9y ago
  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.
- IvanDraga 9y ago
  Theory "Out of Africa" is debunked for a quite a while already
defen 9y ago
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_malaria 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?
- pulisse 9y ago
  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 https://www.biorxiv.org/content/early/2015/10/10/016477
- zeotroph 9y ago
  > vitamin D 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.htm https://www.sciencedaily.com/releases/2014/03/140321095240.h...
  - 9y ago
lerie82 9y ago
so basically the more youre in the sun, the darker your skin gets, thanks science.
amelius 9y ago
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?
- cjensen 9y ago
  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).
- Gibbon1 9y ago
  I think it's a genetic defect that effects 100% of the population. Inability to synthesize vitamin C is another.
ada1981 9y ago
Dairy Industry Astroturfing? ;)
macawfish 9y ago
Do you know what's giving a lot of people white skin these days? Racialized selective breeding.

142 points by pulisse 9y ago

Haha! There you have it social justice fighters. Getting our privilege was hard work! We earned it! (it's a joke in case someone is unsure about it)

alejohausner 9y ago

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.

trhway 9y ago
Milk is calcium. Colder climate - bigger body. That needs calcium. Thus milk and vitamin D, both are necessary. Thus pale skin and lactose. Either alone isn't enough.
TrisMcC 9y ago
Naturally, milk only contains trace amounts of vitamin D. I don't think ancient humans were fortifying their milk.
- op00to 9y ago
  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?
scythe 9y ago
Milk does not naturally contain vitamin D; fish, mushrooms, and egg yolks are the only natural sources, but the mushrooms have to be exposed to sunlight (which is unlikely; they grow in the shade) and nobody eats that many eggs, so only pescetarian cultures retain darker skin at northern latitudes.
badosu 9y ago
The study also points out that there's evidence for sexual selection as well.
masklinn 9y ago
> 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
gumby 9y ago
If you click on the study you'll see that this point is really an artifact of the summary article, not the actual study.
deviationblue 9y ago
> Either way, ancient Northern Europeans had to mutate into pale-skinned milk drinkers, because their land is not very sunny. 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.
- baddox 9y ago
  This seems like an over-application of the (valid) claim that evolution doesn’t have any specific objective. The sentence you quote doesn’t describe an objective. It only describes a necessity.
taysic 9y ago
It is worth noting that some of the people migrating into Europe introducing some of the white skin genes were not from northern regions.

amriksohata 9y ago

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

Arnt 9y ago
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.
- sctb 9y ago
  > Please don't use uppercase for emphasis. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
bonzini 9y ago
Europeans are not a homogeneous group with respect to height; for example the Dutch tend to be taller than the Italians. According to the article, even though average height did increase recently, some disposition and possibly some difference was already there in the genes of people from different parts of Europe.
selimthegrim 9y ago
Many Indians and people of Indian descent (myself included) are in fact lactose intolerant, hence the prevalence of cheese and yogurt products.
- primaryobjects 9y ago
  Cheese and yogurt both have lactose.

asveikau 9y ago

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.

avtar 9y ago
Race, religion, nationalism, social status, me vs. you.. we’ve been at this for ages. Has there really been a point in time where the human collective consciousness hasn’t involved a sense of duality? One supposed exchange from over 2,500 years ago: https://tricycle.org/trikedaily/buddha-talks-brahmin-supremacist/ https://tricycle.org/trikedaily/buddha-talks-brahmin-suprema...
- forapurpose 9y ago
  > Has there really been a point in time where the human collective consciousness hasn’t involved a sense of duality? 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.
deadbunny 9y ago
> 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. Far of "the other" has existed about as long as humans.
irrational 9y ago
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.

giardini 9y ago

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?

Profragile 9y ago
No, because there is NO WAY Europeans came directly from Africans. There is no similarity, no common language, nothing to suggest that there was a close relationship between Africans and Europeans. On the other hand, Europeans have much more similarity with certain Arabic tribes.
freehunter 9y ago
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.
IvanDraga 9y ago
Theory "Out of Africa" is debunked for a quite a while already

defen 9y ago

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_malaria 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?

pulisse 9y ago
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 https://www.biorxiv.org/content/early/2015/10/10/016477
zeotroph 9y ago
> vitamin D 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.htm https://www.sciencedaily.com/releases/2014/03/140321095240.h...
- 9y ago

lerie82 9y ago

so basically the more youre in the sun, the darker your skin gets, thanks science.

amelius 9y ago

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?

cjensen 9y ago
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).
Gibbon1 9y ago
I think it's a genetic defect that effects 100% of the population. Inability to synthesize vitamin C is another.

ada1981 9y ago

Dairy Industry Astroturfing? ;)

macawfish 9y ago

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