Another one bites the dust!

Iain Mathieson and the Reich-Patterson crew have a new paper out on natural selection over the past 8,000 years in Europe, much fortified by the availability of ancient DNA and knowledge of the ancestral mix.

The first point is that lactose tolerance is a fairly late development in Europe, not common (unseen in these samples) until almost the bronze age (first seen in a Bell Beaker skeleton).  In particular they don’t see it (not common) in the Yamnaya, which must mean that it wasn’t a driver of the Indo-European expansion: we were wrong.  I suspect it did exist in the early Indo-Europeans, since we see the same haplotype in India, but one guy wandering around can change the distribution of an adaptive allele. I also don’t understand how they got such a low estimate of its selective advantage (1.5%), but maybe I can winkle that out.

It looks as if there was selection for greater height among the Yamnaya – a possible parallel with Nilotics?

The strong light-skin allele, SLC24A5, does look to be mainly introduced by the early neolithic farmers, but there’s weirdness.  It’s not found in the western hunter-gatherers, but it is there in Scandinavian hunter-gatherers, where you also see the well-known EDAR 370A mutation. It’s even possible that it originated there – but it’s rare in Europeans today, although you see it in Finns a little.






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Solidarity Forever

If you had a gene with a conspicuous effect (like a green beard) that at the same time caused the carrier to favor other individuals with a green beard, you could get a very powerful kind of genetic altruism, one not limited to close relatives.  A very strong effect, one that caused you to act as if other carriers were just as valuable as you are (as if other carriers were your identical twin) could exist, but weaker effects (green fuzz) could also be favored by selection – if you were just somewhat more likely to cooperate with others bearing the mark.  That could be enough to drive strong selection for the gene, and might not even be terribly noticeable.

This might be especially powerful in humans: we have so very many ways of cooperating  or tripping each other up.   Now and then you get partial alignment of interests, and remarkable things happen. If we could all just get along, we could conquer the world and make everyone else our slaves and playthings!

A green fuzz system would be more likely to have originated fairly recently (say the Holocene) because population had increased – particularly important with such an unlikely mutation. Probably it’s even more likely to have never happened at all, but similar things have been found in some biological systems.

And you, could course, engineer it in.

Shortly after  the Green Beards became influential, you’d see a lot of people wearing fake green beards, which would cut down on the advantage and possibly turn green beards into easy marks, chumps doomed to failure.  It would work best if the identifying mark was hard to copy – difficult today, but in the past some things, eye color for example, would have been hard to copy.

This all gets complicated, since it’s not always easy to know what someone else’s best interest is – let along that of the entire Greenbeard race. For that matter it’s not always that easy to know what your own best interest is.

I’m for it, of course:  trying to fighting off such a mutant takeover would make life more interesting.

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Traces of selection

A couple of interesting articles just came out in MBE on how natural selection has affected human populations that ran into problems with trace elements, either too much or too little.  One talked about adaptation to selenium shortages (which I’ve mentioned): this is  a problem in parts of  China, among other places.  It seems that there has been a shift in the frequencies of variants of several genes involved in selenium metabolism – polygenic selection .  The other paper discussed adaptation  to high arsenic levels among people in the northern Argentinian Andes: this involved a partial selective sweep on a variant of a single gene  (AS3MT) that appears to be the major gene for arsenic metabolism.

Probably there have been adaptive changes in response to iodine shortages, which are fairly widespread.  In principle,  shortage or oversupply could be a problem for any essential trace element; but it looks as if, in most cases, the trace element is fairly abundant in the environment (compared to the amount we need) while humans can tolerate a fair amount more than the minimum.  Selenium is something of an exception: shortages and toxicity both occur.

Vitamin shortages and surpluses we know something about.  I’m sure that most of my readers have learned their lesson and no longer gobble polar bear liver.  It looks as if you can suffer from an ergothioneine shortage from a wheat diet, and a more-active form of the ergothioneine transporter has undergone a partial sweep in southern Europe (EEF). Interesting that dietary scientists aren’t sure what problems are caused by ergothioneine shortages: but the existence of a specific ergothioneine transporter, and that partial sweep, sh0w it does indeed do something useful.  That’s a a useful approach to showing that something is useful or essential in humans, easier than putting a platitude of sophomores on a  special diet and seeing if their hair falls out  or they develop ED – show that there is specific molecular machinery for  importing it.

I think there’s a fair chance that some populations – I’m thinking of maize and Amerindians – have adapted to  poor amino acid quality: having too many of some essential amino acids and too few of others (like lysine): like Scrabble with more ‘Q’s than ‘U’s.

There might be adaptation to a cassava diet: cyanide tolerance.  In South America, of course, not Africa.

There are lot of examples in which any sensible person (of which there are  about five) knows that some between-population trait difference almost certainly has  a genetic cause (because we always see it in every sample of that pop, in different environments) but we don’t know the genetic details, or have only a limited knowledge.  For example, some populations have a lot more trouble handling alcohol than others – which, pace Robin Hanson , is genetic.  We know something about the basis of this among East Asians, but I don’t think we know the genetic architecture in other populations.

What  other factors that haven’t been considered  at  may have selected for various things in humans ?  Please  say something that we haven’t heard a million times before.

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Brotherhood of warmblood

All mammals are more closely related to each other than they are to any bird. That’s why an otter or a porcupine will instinctively help a rabbit that’s being chased by a hawk.

Except that they don’t.  Why not?


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Genetic Convection

Advantageous gene variants certainly spread by people marrying someone from the next village, but they can also be spread by population movements – settling virgin lands, farmers pushing aside foragers, and of course conquest, our old friend. If a Fisher wave is diffusion, genetic transport because of those population movements could be compared to convection, as our commenter RCB has suggested.

People are sometimes interested in estimating the point of origin of a sweeping allele: this is probably effectively impossible even if diffusion were the only spread mechanism, since the selective advantage might well vary in both time and space. But that’s ok, since population movements – genetic convection – are real and very important. This means that the difficulties in estimating the origin of a Fisher wave are totally insignificant, compared to the difficulties of estimating the effects of past colonizations, conquests and Völkerwanderungs. So when Yuval Itan and Mark Thomas estimated that 13,910 T LCT allele originated in central Europe, in the early Neolithic, they didn’t just go wrong because of failing to notice that the same allele is fairly common in northern India: no, their whole notion was unsound in the first place. We’re talking turbulence on steroids. Hari Seldon couldn’t figure this one out from the existing geographic distribution.

Same thing with the EDAR allele: Kamberov et al estimate that it originated in central China, but there’s no reason to think that they’re right. Not least because we don’t even understand what the advantage is.

It looks as if the EDAR mutation was fairly common among the original Amerindians. If so, how rapidly did it spread in the Americas? Just as fast the the place was colonized : deep into South America in a thousand years.

On the other hand, the mere fact that an allele has spread very far is a strong hint that it was carried by population movements, not just a Fisher wave. As we gradually figure out ancient population movements, to a large extent using ancient DNA, we will have a better idea of the origin and trajectory of such mutations. Seeing LCT 13910 in both Europe (especially northern Europe) and India suggests that was it was carried along by the Indo-European expansion. The delf508 Cystic fibrosis mutation (also found in India) probably was as well, and perhaps the common 35delG deafness mutation. On the other hand, SLC24A5 and Factor V Leiden probably came with the Middle Eastern farmers.

Many of these allele look like defenses against infectious disease, or some kind of adjustment to an agricultural diet: you’d expect that they originated among either the EEF farmers or the Indo-Europeans, not the old Mesolithic foragers of Europe.

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Various crap

The world is infested by various nutty ideas, and mostly you just have to ignore them, at least until you become King and release the hounds. But someone needs to oppose them, else the young and naive may fall victim. Now and then I get the urge, fortunately not too often.

One busy area is WWII revisionism.

1. The Roosevelt administration supposedly had prior knowledge of the attack on Pearl Harbor and deliberately refrained from telling Admiral Kimmel and General Short. Not true: basically pretty silly. Suppose you were a Machiavellian willing to take a hit in order to stir up the public: you might be willing to lose a ship, but not most of the Pacific fleet! Most expected an attack, but not at Pearl. I could go on with the details of the JN series codes, the extent to which they were broken: what we could read, when we could read it, when the Japanese switched codes, etc. In December ’41 we couldn’t read a thing. The Kidō Butai avoided the shipping lanes, was radio silent. Radar on Hawaii was a week old: stealth was easy in those days.

Roosevelt expected that there would probably be a war if we continued to oppose Japanese expansion in China but he didn’t expect the war that we got, with a wildly successful first campaign for Japan.

2. Icebreaker. Victor Suvorov (alias) wrote a book saying that the Soviets were poised to invade the Nazi-controlled lands in the summer of 41. Silly: the Soviets were desperately afraid of a war with Germany, because they feared that they’d lose. So afraid they ignored credible reports of the coming attack from their own intelligence guys, Western powers, even from the German ambassador! it was too horrible to be true.

The German Army looked damned good in defeating France, while the Soviets had had a lot of trouble with Finland, caused in part by having just shot most of the higher officer corps. That and Simo Häyhä.

If the Sovs were within a couple of weeks of launching invasion, you’d think that they would have called up the deep reserves, bothered to get all of their tanks working, stockpiled fuel, run recon overflights, snuck sappers into German-occupied territory (to sabotage bridges and cut communications lines), finish reorganization of their tank corps, etc. etc.. – most of which the Germans did do, of course. None of which the Soviets did. The Soviet high command expressed great concern about their frontier about not giving Hitler an ‘excuse” for starting a war – like he needed one! Hitler may be the only person that Stalin really, truly trusted in his adult life: which must prove something.

3. Other Losses. No, Eisenhower did not scrag hundreds of thousands of German POWs. We let a large number of them go as soon as we caught them : usually with the boys and old men of the Volkssturm, sometimes with regular army, not with SS. I was just reading some comments from an uncle who was a company commander: they had zillions of Germans trying to surrender to his division, rather than the Russians. His division had 65,000 German prisoners: they let most of them walk home, other than the SS, largely because they couldn’t figure out what else to do with them.

4. The Werwolf resistance in Germany – how our occupation was (not) plagued by guerrilla warfare. This one is funnier: theory #1 appealed to people who were emotionally traumatized by Pearl Harbor (many people) and/or hated Roosevelt (many people). #2 appeals to Germans, and to people who hated the Soviets (not without reason) – and, of course, to people who are just generally goofy. # 3 basically appeals to Nazi sympathizers, not necessarily German. But this last one started out as a fairly stupid but innocent satirical article on the Internet, a pretend Reuters article from 1945 talking about how people in the US were getting sick of occupying Germany in the face of all that guerrilla resistance. The satiric article plainly stated that it was not a real Reuters article – it was satire, in support of the US continuing to occupy Iraq. People copied the article and left off the bit about it being satire. Some speechwriter for Rumsfeld used it, presumably without A. knowing it was not a real Reuters article and B. naturally knowing nothing about US history (or anything else). Once Rumsfeld had publicly argued that we had the same problems in Germany (except that it was deadly blonde Frauleins, rather than IEDs) it became a thing. Nobody in high office ever admits that they’re wrong: presumably it would leave little time for anything else. Good Busheviks knew that they should believe in it – I’m sure that some still do.

Rumsfeld even improved on it, later -talked about all the chaos and bloodshed after the American revolution (undoubtedly moderated by American near-gunlessness). Condi used it, I would guess because she was behind on her idiocy quota.

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It looks as if the people that founded the Corded Ware culture, largely eliminating the previous LBK-like farmers, were the Yamnaya, themselves a mixed population, approximately half some kind of eastern hunter-gatherer and half some farming populations genetically similar to Armenians.

In which of those two populations did primitive Indo-European – the language – originate? I’m betting on the hunters. I suspect that they’re the ones that domesticated the horse: horses weren’t very common south of the Caucasus, and it doesn’t look as if they were domesticated there.

It’s not easy for farmers to conquer horsemen: easy the other way around.

The dominant Y-chromosome lineages among the Yamnaya (and later, most of Europe and India) originated in those hunters, not in a Middle Eastern population. It is hard to believe in a scenario in which the farmers conquered the hunters and then forced their women on them (Take my wife, please!).

Analyzing old myths and legends, various people smoking superior kinds of dope have argued that there was a ‘war of the functions” – formation wars – at the beginning of the Indo-Europeans, where a group of warriors and priest/magicians/judges conquered farmers. Two estates absorbed the third. Possibly referenced in those sobbin’ women, the Aesir-Vanir war, the Mahabharata, etc.

Moreover, something relevant happened earlier, before the Yamnaya made their big move. Somebody – pastoralists – smashed Old Europe in the Balkans a good deal earlier, and someone (maybe the same people) brought a very early branch of Indo-European into Anatolia ( Hittite, Luwian, Palaic, Carian, etc. ) Then there are the Indo-Aryan languages, and Tocharian: looking at those branches, and the genetics of early speakers, should resolve this problem. For example, if you find a  population of Indo-European speakers that has that eastern hunter-gatherer genetic signature, without the Armenian-like signature, probably the language originated in the hunters. Or vice versa.

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