Eight thousand years of natural selection in Europe

April 26, 2015 8:49 PM

How did Europeans become "white"?

see also:Eight thousand years of natural selection in Europe

The arrival of farming in Europe beginning around 8,500 years ago required adaptation to new environments, pathogens, diets, and social organizations. While evidence of natural selection can be revealed by studying patterns of genetic variation in present-day people, these pattern are only indirect echoes of past events, and provide little information about where and when selection occurred. Ancient DNA makes it possible to examine populations as they were before, during and after adaptation events, and thus to reveal the tempo and mode of selection. Here we report the first genome-wide scan for selection using ancient DNA, based on 83 human samples from Holocene Europe analyzed at over 300,000 positions.

Why Are Europeans White?

“White,” of course, is a a social designation. The question really is, “Why are northern Europeans depigmented?” Here is a map of human skin tone. The natives of northern Europe are oddly light-skinned. They are paler than anyone else on earth.

refers to The Paleo-Etiology of Human Skin Tone

posted by the man of twists and turns (44 comments total)

What's the explanation for increased height in northern latitudes? Are tall people closer to the sun? Less shadowed by short people? Capable of milking aurochs without using a stepladder?<sup>1

1</sup> The stepladder theory explains

• Why domestic cattle are shorter than the ancestral population;
• Why selection for lactase was accompanied by selection for height;
• Folk-memories of "brownies", who could be bribed with basins of milk.²

² Presumably the "little people" were too short to milk cows themselves.
posted by Joe in Australia at 9:02 PM on April 26, 2015 [14 favorites]

How did the Sciencemag.org comment section become hella racist?

Interesting too the couple of animal-related discoveries, the lack of milk digestion genes in farmers (decreasing the value of domesticated animals) and the lack of evidence for disease, which has often been part of the model for folks like Jared Diamond in explaining the dominance of agriculture over hunting/gathering.
posted by klangklangston at 9:05 PM on April 26, 2015 [1 favorite]

How did the Sciencemag.org comment section become hella racist?

It's on the internet.

Seriously though, some racist place probably linked to it. I notice this happens when drudgereport links to things - the comments get more offensive than the general internet level of offensive.
posted by el io at 9:10 PM on April 26, 2015 [14 favorites]

This does not explain freckles, mound building and Barbados.
posted by clavdivs at 9:47 PM on April 26, 2015 [1 favorite]

to be fair, based on the guy from there that I know, nothing can truly explain Barbados
posted by DoctorFedora at 11:25 PM on April 26, 2015 [1 favorite]

What's the explanation for increased height in northern latitudes?

Scientists try to answer why Dutch people are so tall

Summary: Taller Dutch men and women more fertile than short people.
posted by Mister Bijou at 12:18 AM on April 27, 2015 [1 favorite]

I think the lede's a bit buried there, in the middle of the second link:

What does skin tone have to do with eating cereal? Even in darkness, humans get vitamin D from eating meat and fish...

There is only one spot on the planet where grains will grow despite sub-arctic sunlight.

It is where the warm waters of the Gulf Stream wash ashore. The Baltic is the only place on earth where ocean currents keep it warm enough to grow grain despite dim sunlight.

When the inhabitants of this region switched to grain about 6 KYA, they suddenly got insufficient vitamin D to survive. They had stopped eating mostly meat and fish in a place where sunlight was too dim to produce vitamin D in normally pigmented skin.

And so they adapted by retaining into adulthood the infantile trait of extreme paleness. Blonde hair and blue eyes were other infantile traits that were just swept along accidentally.

So, while "everyone knows" that Europeans need pale skin to get vitamin D, it's actually a consequence of diet as well. People who eat lots of meat and fish get vitamin D from those sources. White skin was only necessary for people living off agriculture rather than hunting, in a region with little sun that's still warm enough for basic farming.
posted by TheophileEscargot at 12:32 AM on April 27, 2015 [40 favorites]

Holy crap, yeah do NOT read those comments. Thanks for the link, though!
posted by brundlefly at 1:27 AM on April 27, 2015

Only the Baltic? I'd have thought it was all of NW Europe. Those ocean currents must be losing their edge a bit once they've forced their way up the Channel, across the North Sea, up around the top of Denmark, down the Kattegat and through the Danish islands.
posted by Segundus at 1:30 AM on April 27, 2015

Well, it's only that blog post that mentions the Baltic and usually only together with the North Sea. And while I don't think the gulf stream actually flows into the Baltic, the heat from it actually does via exchange through the atmosphere, which I think shows up in this image.
posted by traveler_ at 2:03 AM on April 27, 2015

Yep, unless it was specifically written for a local audience, I don't understand the repeated Baltic mentions of that post. It's true that light hair and eyes are most prevalent around the Baltic, but as far as I know, light skin is most common in Ireland and Scotland. I can't find a detailed map for European skin colour, but I imagine it tracks this map of annual sunshine pretty closely.
posted by kersplunk at 2:29 AM on April 27, 2015

You'd have to eat a whole lot of meat to get even the 400IU amount (and that recommended amount in northern European countries is already based on pale skinned people who are adopted to get more vitamin D from sunlight, note that the US government recommends 600IU) . The only meat that I see in our local nutrition database that has any significant amount of vitamin D is beef liver, and the image in the last link, that is supposed to show how much vitamin D there is in meat, confirms that. You'd still have to eat 10 ounces of that to get even near that 400IU recommendation. Fish is the only real source of vitamin D (now) in people's diet. One herring gives you about double the minimum recommended amount.
posted by blub at 2:37 AM on April 27, 2015

Vitamin D? Ah, yes, herrings....

"Scandinavian burial mounds dating from Neolithic times contain herring bones. Humble though it may be, and about as glamorous as a galosh, it is a fish that has shaped the political and social history of Europe like no other, with the possible exception of cod. The Hanseatic League, the medieval economic guild, came into being because the Germans had the salt that the Scandinavians coveted as a preservative for their herrings, and British and Dutch sea power was built on the back of the herring trade.

Herrings remain a staple in the diets of northern Europeans -- not only the Scandinavians but also the Dutch, British, Germans and others."

Source: NYT
posted by Mister Bijou at 2:50 AM on April 27, 2015 [11 favorites]

I was convinced this was a topic we'd discussed before. Then I remembered that it was actually in an AskMe I posted in 2013...
posted by sodium lights the horizon at 4:41 AM on April 27, 2015 [1 favorite]

So I don't have to refer to my fellow honkies as "pink" -- which only confused the ones who thought I was talking about their gay or socialist enemies -- and can now talk about "depigmented mutants".
posted by fredludd at 4:46 AM on April 27, 2015 [2 favorites]

> Yep, unless it was specifically written for a local audience, I don't understand the repeated Baltic mentions of that post.

I think it mostly a matter of where in Europe ancient DNA samples have been obtained so far. Here's a map from another study of ancient European DNA (Haak, et al., " Massive migration from the steppe is a source for Indo-European languages in Europe") showing where the samples came from. Mathieson et al. were probably using pretty much the same set of samples for their study, because there's only so much available. (As you can see from the map, ancient autosomal DNA from the UK and Ireland just doesn't seem to be available yet, and there are a lot other gaps.)
posted by nangar at 5:14 AM on April 27, 2015

So, uh, I guess vitamin D is just a red herring?
posted by I-baLL at 5:21 AM on April 27, 2015 [7 favorites]

On Krypton, yeah.
posted by No-sword at 5:40 AM on April 27, 2015 [4 favorites]

What's the explanation for increased height in northern latitudes?

The classic answer is Bergmann's and Allen's "rules". Essentially, that people with bigger bodies (Bergmann) and smaller extremities (Allen) stay warmer in the cold. Cold-adapted people would have big torsos and short legs and arms in comparison to equatorials, by these theories.

It turns out, that may be not be the case at all, that "body size follows the duration of the annual productivity pulse, so that body size is a function of availability of nutrients and energy during periods of growth. Correlations between body size and temperature are shown to be spurious. If reduction in relative surface area is indeed an adaptation to conserve heat, then mammals should increase in size from south to north at rates two orders of magnitude greater than they do."

In other words, access to food and ecological richness of the area is probably more important.
posted by bonehead at 6:39 AM on April 27, 2015 [4 favorites]

And so they adapted by retaining into adulthood the infantile trait of extreme paleness. Blonde hair and blue eyes were other infantile traits that were just swept along accidentally.

Ha! Retained infantile traits! My dog and I have something in common now!
posted by Blue Jello Elf at 6:45 AM on April 27, 2015 [3 favorites]

And now I can say why I can't leave my house in any non-winter season without full length sleeves and pants. At least if I want to keep my skin from sloughing off.
posted by Ferreous at 6:50 AM on April 27, 2015 [1 favorite]

any theory that purports to explain why europeans are white based on environment needs to also explain why Australians are white too.
posted by MisantropicPainforest at 9:00 AM on April 27, 2015

Pretending to take your comment seriously, because my parents were Swedish and I was born in Australia. I only mention this because my skin literally begins to burn in 10 minutes of midday sun. Once so bad I had bubbles of blisters as if I'd been deep-fried. Somewhat supportive of the climactic theories proposed here.
posted by adept256 at 9:11 AM on April 27, 2015 [1 favorite]

So how come Eskimos don't have blonde hair?
posted by mareli at 9:29 AM on April 27, 2015

mareli, because their diet is mostly meat and fish.
posted by nonasuch at 9:31 AM on April 27, 2015 [3 favorites]

any theory that purports to explain why europeans are white based on environment needs to also explain why Australians are white too.

This is a joke that I'm not getting, right?
posted by Mrs. Pterodactyl at 9:46 AM on April 27, 2015 [12 favorites]

But historic Swedes must have eaten a lot of fish as well, no?

Certainly there must be room for a hypothesis that it was just a mutation that was preferential from a mate-selection Point of view as opposed to have any real survival rate improvements.

Basically historic Swedish dudes liked blonde women more. I mean, that's not a totally insane theory right?
posted by GuyZero at 9:47 AM on April 27, 2015

But historic Swedes must have eaten a lot of fish as well, no?

Maybe it depends on the availability and types of fish. Swedes have preserved fish, lutfisk, in their culture.
posted by ZeusHumms at 10:16 AM on April 27, 2015

I stress that I believe ALL people are beautiful. And no-one here is going to deny people's sexual preferences.

There must be some reason my lovers have been predominately redheads. Anecdotal, but no, not a totally insane theory.
posted by adept256 at 10:27 AM on April 27, 2015

"any theory that purports to explain why europeans are white based on environment needs to also explain why Australians are white too."

they are criminals of the law of natural selection
posted by klangklangston at 10:48 AM on April 27, 2015 [12 favorites]

So, for the box marked "Other" I can put "depigmented mutant?"

Should that be capitalized?
posted by mule98J at 10:54 AM on April 27, 2015 [2 favorites]

What's the explanation for increased height in northern latitudes?

the icelandic government would officially like to make absolutely clear that elves are in no way involved.
posted by poffin boffin at 10:56 AM on April 27, 2015 [6 favorites]

Does the Norwegian government blame trolls then?
posted by I-baLL at 11:03 AM on April 27, 2015 [1 favorite]

I'm not convinced by the science they're quoting in that "The Paleo-Etiology of Human Skin Tone" article. I'd be interested to see exactly how much data went into the 1977 updating of Biasutti's 1941 map.

This is what makes me scratch my head:
"With two minor exceptions, the genetic trait for blonde hair precisely matches that for fair complexion ... (The two minor exceptions are the fair-skinned but brown-haired people of Bordeaux and the blonde but swarthy descendants of the Volga Rus.)"

Here in Ireland there are at least four common types of pale-skinned people: pale red-heads, pale people with brown hair and light hazel/brown eyes, pale people with dark brown or black hair and blue or grey eyes, and pale blondes. Of these, I'd say the blondes are the rarest, and pale brunettes are a lot more common.
posted by Azara at 11:53 AM on April 27, 2015 [3 favorites]

What's the explanation for increased height in northern latitudes?

Obvious suggestion from what I remember of the dinosaur ecto/endothermic debate: larger organisms have a lower surface area:mass ratio due to the square-cube law. Plus larger size increases viability of the homeothermic approach to body temperature regulation.

So for two reasons of basic physics as applied to physiology, greater body mass means longer survival time outdoors, which is essential for survival when hunting meat during the winter.

This obviously ignores the whole mate selection/sexual preference factor, which seems likely to play a far larger role when we start talking about natural selection in sentient animals. Point is: at best the whole body temperature thing is just another moderate contributing factor, but there you go.
posted by Ryvar at 11:54 AM on April 27, 2015

Ryvar, see Bonehead's comment.
posted by klangklangston at 12:34 PM on April 27, 2015

My bad, totally missed that comment and it makes a lot of sense as an argument.
posted by Ryvar at 12:37 PM on April 27, 2015

Basically historic Swedish dudes liked blonde women more. I mean, that's not a totally insane theory right?

I thought the Vikings had a thing for red hair. Apparently the prevalence of the red hair gene in Ireland and northern Britain, and anti-redhead prejudice in Britain (as embodied in the phrase “red-headed stepchild”, for example), both are said to correlate to red hair having been a sign of Viking ancestry.

(And this didn't extend just to human hair preference; a study of feline genetics found that the red-hair gene in cats originated in the Middle East and spread along the Mediterranean and up the North Sea, following the ancient Viking trade route, suggesting that Viking sailors were fond of adopting any ginger cats they may have found in Middle Eastern ports.)
posted by acb at 2:49 PM on April 27, 2015 [2 favorites]

herring
posted by bukvich at 5:49 PM on April 27, 2015

It's almost certainly a bit from column A, a bit from column B. Ryvar even brings it up when he throws in the mate selection/sexual preference factor variable.

The comments section at sciencemag and nature are really weird to me. Sciencemag moreso, since there aren't a lot of user comments in nature. Rarely do real academics actually post there. In non-political pieces, it's mostly just cranks and trolls. Cell doesn't do as much news/editorials and they don't get a lot of user comments.

Very stark contrast to reader comments section in the BMJ, the CMAJ, even JAMA - all medical journals. Comments, almost certainly, are moderated. Despite the occasional politics (both capital p and small p) nonsense posts, the commentary is generally of high quality and stand-out ones are pretty routine.
posted by porpoise at 7:38 PM on April 27, 2015

Mister Bijou quoted:

"Scandinavian burial mounds dating from Neolithic times contain herring bones. Humble though it may be, and about as glamorous as a galosh, it is a fish that has shaped the political and social history of Europe like no other, with the possible exception of cod."

MeFi's own Rumple has an interesting blog post on the herring economy of America's Northwest Coast. Herring was actually the most commonly found fish in more than half "adequately surveyed" archaeological sites, but all we hear is salmon, salmon, salmon. Why?

[...] if we stereotype all fish traps as being directed towards salmon, we miss the labour investment that went into harvesting herring and downgrade it accordingly. If we interpret bones points as fish hook barbs and not herring rake tines, we underestimate herring. Of course, herring are small fish with small bones, and you need to be fairly dedicated to fine-mesh water-screening to feel confident you’re getting the herring, or enough of them – or you must be quite thorough in your column sampling. It’s even more impressive that they are so common and ubiquitous in the face of a perhaps patchy record of half-hearted recovery efforts.

It's well worth reading, especially for the description of herring spawn as being a "rich, nutrient-dense, yet storable, delicious marine omelet".
posted by Joe in Australia at 8:59 PM on April 27, 2015 [2 favorites]

Northern Europeans chose their mates, among Scandinavian peoples marriage occurred post conception.

Interest provokes variation, while control (arranged cousin marriage) promotes sameness, security.
posted by Oyéah at 9:50 AM on April 28, 2015

Did natural selection make the Dutch the tallest people on the planet?
posted by the man of twists and turns at 11:02 PM on May 5, 2015

Convergent adaptation of human lactase persistence in Africa and Europe
posted by the man of twists and turns at 9:16 PM on May 10, 2015 [1 favorite]