Gene Flow III

This is a table of the distribution of edar370a, the allele that plays a big role in making Northeast Asians look the way they do.  I’ve talked about it before.

Note that the allele frequency is generally zero in African populations, and is over 90% in the Han. It’s also pretty common in pure-blooded Amerindians, which means it’s  fairly old, since they came over from Asia 15-20 k years ago. It’s been favored by selection, in some unclear way, which can easily drive an allele from one copy to the high frequencies we see today in China, given maybe 30,000 years.

Most alleles don’t vary enormously in frequency between different human populations, because those populations have a common origin  – maybe 70,000 years ago for people outside of sub-Saharan Africa, maybe 150-250 k years ago for the various groups in sub-Saharan Africa.  But this one does, and there are others, like DARC ( near 100% in Africa, unknown in China).

You can find populations all the way into Europe ( east and north) and India that have low, non-zero levels of EDAR370a. So there was some gene flow between such groups over the past few tens of thousands of  years, but not a lot.  How much gene flow was there between more distant groups ( over the past thirty thousand years or so) , say between China and the Khoisan? Or between China and Spain, China and England, China and Italy?

Zero.

 

 

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An American Dilemma

Today we’re seeing clear evidence of genetic differences between classes: causal differences.  People with higher socioeconomic status have ( on average) higher EA polygenic scores. Higher scores for cognitive ability, as well. This is of course what every IQ test has shown for many decades.

It’s driving regional migration in the UK:  people with higher scores in depressed areas (like mining towns) are leaving for London, leaving those towns even more depressed.

There is ongoing decline in those polygenic scores, as observed in other studies and as predicted by demographers and science-fiction writers many years ago.

So we have classes that are genetically different, with upper classes genetically smarter.  Could we have populations or ethnic groups that were genetically smarter?  Obviously: simply create one by dropping a bunch of high-SES  ( or high-scoring) people on a deserted island.  Do we already have such populations? ( although, if I’m not mistaken, that would be racist.)

Well, sometimes a group has high scores, high ability because it is a far-from-random sample, while not being particularly genetically distinct or separate. ( either today or in the past).  College professors are smarter than average, at least in fields like math and natural science, but they are drawn from many populations and do not marry entirely or primarily  within their group. In fact they hardly breed at all, nowadays.  Los Alamos High has the highest test scores in New Mexico: that’s an unrepresentative sample.

Nigerians in the UK seem to be a very non-random sample, highly selected: most of them have at least some college while maybe 5% of the general population in Nigeria does.  I was was somewhat surprised to see this: most of the migrations I’m more familiar with (mostly US major immigration streams) are not so unrepresentative. Of course if they stayed in the UK and almost entirely married among themselves, they’d be a new, smarter-than Nigerian ethnic group. But that, too, would be racist.

Let’s look at Ashkenazi Jews in the United States. They’re very successful, averaging upper-middle-class.   So you’d think that they must have high polygenic scores for EA  (and they do).

Were they a highly selected group?  No: most were from Eastern Europe. “Immigration of Eastern Yiddish-speaking Ashkenazi Jews, in 1880–1914, brought a large, poor, traditional element to New York City. They were Orthodox or Conservative in religion. They founded the Zionist movement in the United States, and were active supporters of the Socialist party and labor unions. Economically, they concentrated in the garment industry.”

And there were a lot of them: it’s harder for a sample to be very unrepresentative when it makes up a big fraction of the entire population.

But that can’t be: that would mean that Europeans Jews were just smarter than average.  And that would be racist.

Could it be result of some kind of favoritism?  Obviously not, because that would be anti-Semitic.

 

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The Paras

Sometimes in a long struggle, the players have a felt need to believe that it all means something: that the buddies they lost died for something important, that they made a difference…  Sometimes it’s even true.  But it ain’t necessarily so.  A lot of wars are over nothing of long-term value or importance, and of course sometimes your side loses, which decreases the chance that your sacrifices have some kind of cosmic payoff. Sometimes this means the goals of the war somehow become more important as the cost increases, because they need to  – sunk costs fallacy on steroids.

For example, if Meade had crushed the Army of Northern Virginia  when it was pinned against the Potomac after Gettysburg, we’d all be better off, but the Civil War would occupy considerably less territory inside people’s heads today.

Or consider Vietnam: I’ve known people that were sure we were ” wearing down” the Soviet Union in Vietnam, even though we outspent them there by at least 20-1 – not even considering casualties !

In the Algerian War, the French ended up doing a lot of stuff that no true Scotsman* would even consider: lots of torture, lots of  shooting civilians. As they got rougher, the imaginary future they were fighting for became ever more golden, ever more unrealistic – it was one in which the Algerians  were fully integrated French citizens, something that had never made sense and was completely impossible after guys like Massu had used “all means necessary” to win the Battle of Algiers.  The Paras at this point didn’t have much sympathy for the pieds noirs, who weren’t crazy enough to share that vision. But then those French officers had been through a lot – defeated by Germany, embarrassingly saved by the Anglo-Americans, losing in  Vietnam: pre-adapted for nuttiness.

 

  • except the Campbells, of course.

 

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Republics

Strikes me that in some parts of the world, they were fairly common in the past, while in other parts, practically nonexistent. I’m wondering the extent to which they were an Indo-European thing.

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Carryover vs “Far Transfer”

It used to be thought that studying certain subjects ( like Latin)  made you better at learning others, or smarter generally – “They supple the mind, sir; they render it pliant and receptive.” This doesn’t appear to be the case, certainly not for Latin – although it seems to me that math can help you understand other subjects?

A different question: to what extent does being (some flavor of) crazy, or crazy about one subject, or being really painfully wrong about some subject, predict how likely you are to be wrong on other things? We know that someone can be strange, downright crazy, or utterly unsound on some topic and still do good mathematics…  but that is not the same as saying that there is no statistical tendency for people on crazy-train A to be more likely to be wrong about subject B.  What do the data suggest?

I’m mostly talking about cases where A and B have no obvious relationship – we know that a dedicated Marxist is more likely to have wrong notions about genetics, since heritability offends him ( probably gravity and levity do as well).   Probably also worth considering whether the individual in question achieved craziness on his own or was immersed in it from birth.

Lastly, sometimes that correlation must be negative: certain flavors of crazy likely make you less  likely to be wrong about certain other things.

 

 

 

 

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Let justice be done, though the heavens fall

If we had operated on that motto at the end of WWII, we would have executed a whole lot more Germans and Japanese than we did.

 

 

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Gene genealogies vs population splits

Genes have genealogies, just as populations do. Usually, a gene’s  genealogy is the same as that of its species.  For example, turtles have their own versions of hemoglobin, and the common ancestor of those turtle hemoglobin genes is some ur-turtle  hemoglobin ( or is it turtle ur-hemoglobin ?) a long time ago.  This is a stochastic thing: it happens when only a single version of a gene survives – after that occurs, gene trees and population trees match, at least until the next split.

But it ain’t necessarily so, especially in cases where two species separated rather rapidly, or when the splitting populations are large – even more so when populations haven’t yet speciated at all.  When the gene tree conflicts with the population tree, we call it incomplete lineage sorting.  For example, gorillas split off before humans and chimpanzees separated, but some of the human genome (  ~30% ) is more similar to gorillas than it is to chimpanzees.   So, gene trees don’t match species trees very well  among humans, chimps and gorillas – although they do just fine between, say, humans and bears.

How much lineage sorting would you expect from human populations that have been  separated for, say 100,000 years? 250,000 years?  Close to zero.  Hardly any. So, can you use the fact that  human gene genealogies do not match apparent human population splits to prove those splits never happened – that there  had always been lots of gene flow between far-distant populations, say between sub-Saharan Africa and Siberia?  Presumably using magic carpets?

You could, but only if you were a bird-brain.

 

 

 

 

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