Science, race, and genetics

June 3, 2005 10:08 AM

The Natural History of Ashkenazi Intelligence (PDF). A fascinating new theory from physicist turned renegade evolutionary theorist, Gregory Cochran (see this Atlantic Monthly cover story on Cochran's already path-breaking germ theory of disease), and genetic anthropologist Henry Harpending, proposes that a unique evolutionary history, and a number of improbably clustered neurologically related genetic diseases among Ashkenazi Jews could help explain their incredible intelligence test scores and extraordinary intellectual achievements (e.g. Ashkenazi Jews are 3% of the American population but win 27% of the Nobel Prizes). The paper is set for publication in the Journal of Biosocial Science, and is already getting major press in the New York Times and The Economist. Does the recent Harvard fracas over Larry Summers herald a new "arms race" in academic debate about genetics, man and society for the 21st century? [compelling post by Jason]
posted by mathowie (68 comments total)

Here's the abstract:

This paper elaborates the hypothesis that the unique demography and sociology of Ashkenazim in medieval Europe selected for intelligence. Ashkenazi literacy, economic specialization, and closure to inward gene flow led to a social environment in which there was high fitness payoff to intelligence, specifically verbal and mathematical intelligence but not spatial ability. As with any regime of strong directional selection on a quantitative trait, genetic variants that were otherwise fitness reducing rose in frequency. In particular we propose that the well-known clusters of Ashkenazi genetic diseases, the sphingolipid cluster and the DNA repair cluster in particular, increase intelligence in heterozygotes. Other Ashkenazi disorders are known to increase intelligence. Although these disorders have been attributed to a bottleneck in Ashkenazi history and consequent genetic drift, there is no evidence of any bottleneck. Gene frequencies at a large number of autosomal loci show that if there was a bottleneck then subsequent gene flow from Europeans must have been very large, obliterating the effects of any bottleneck. The clustering of the disorders in only a few pathways and the presence at elevated frequency of more than one deleterious allele at many of them could not have been produced by drift. Instead these are signatures of strong and recent natural selection.

I'd like to thank Matt, for letting a new user cheat by posting for me.
posted by Jason Malloy at 10:13 AM on June 3, 2005

My incredible Ashkenazi intelligence tells me this thread will not end well.
posted by escabeche at 10:14 AM on June 3, 2005

I personally think differences in race are not genetic, but cultural. My jewish wing of the family prizes academics above all else and I wouldn't be surprised to hear that many nobel prize winners were the result. It seems to be a pretty common thing for jewish families to stress education to their children.
posted by mathowie at 10:22 AM on June 3, 2005

escabeche: that was funny!
posted by blindcarboncopy at 10:25 AM on June 3, 2005

mathowie : "I personally think differences in race are not genetic, but cultural. My jewish wing of the family prizes academics above all else and I wouldn't be surprised to hear that many nobel prize winners were the result. It seems to be a pretty common thing for jewish families to stress education to their children."

But what if the Jews learnt to treasure and emphasize education because that is what they observed they were good at? You know: 'cultivate your strengths'.


/just playing "devil's advocate".
posted by Gyan at 10:29 AM on June 3, 2005

I, for one, welcome our new Ashkenazi overlords and their mighty brains. Apparently they are the chosen people after all!
posted by SenshiNeko at 10:33 AM on June 3, 2005

There are no public outcries when scientists find that Ashkenazi Jews are more likely to suffer from Tay-Sachs Disease (caused by double recessive alleles), but when they find evidence for natural selection's role in their IQ, suddenly it's a whole different ballgame.

I mean, I understand the reason people react differently to the news, because it seems like there's more at stake. Some recent pundits (I'm looking at you, Steven Pinker) have argued the outcome of genetic findings is irrelevant, because we are all individuals, and must be judged as such independently of the statistics. But I think this overglosses the complexity of the matter-- for quick 'n' dirty judgment heuristics, sterotypes are, pragmatically speaking, quite useful. So I don't see how results such as these (should they be true) would have no effect on a rational person's behavior.

"It would be hard to overstate how politically incorrect this paper is," said Steven Pinker, a cognitive scientist at Harvard, noting that it argues for an inherited difference in intelligence between groups. Still, he said, "it's certainly a thorough and well-argued paper, not one that can easily be dismissed outright." ... said the Ashkenazi Jew. heh.
posted by mowglisambo at 10:35 AM on June 3, 2005

Gyan: Then that would be some pretty strong evidence of adaptive intelligence. :-) Why bother hanging your proverbial hat on the stuff you're not good at?

/self-justifying
posted by GrammarMoses at 10:37 AM on June 3, 2005

The Times article had some statistics showing greatly higher percentages than the general population of people having IQs over 140. I am not sure that comes merely from education.

Given that the research involves a generally positive trait among a persecuted group perhaps it can actually be discussed (in general, not just here on MeFi) without the discussion devolving into charges of racism and bigotry merely because it was discussed. In any event, it is a very interesting hypothesis.
posted by caddis at 10:37 AM on June 3, 2005

This is a crock. I'd go with the founder's effect. You're more likely to survive and thrive under centuries of persecution if you're smart and clever and nimble--it's simple. (and most of us were not moneylenders--i believe it was always a very small proportion of us--in addition, they're repeating old racial stereotypes, stereotypes that led to that very persecution.)
posted by amberglow at 10:38 AM on June 3, 2005

You're more likely to survive and thrive under centuries of persecution if you're smart and clever and nimble--it's simple.

Then how do you explain the irish?

and most of us were not moneylenders--

And those who were, were often "beards" for Christians, because many sects disallowed moneylending.
posted by jonmc at 10:46 AM on June 3, 2005

He's not arguing that social factors don't play a strong role - just that they don't play the only role, and that they are complemented by the selection he describes. I think this is fascinating.

Unfortunately my principally Ashkenazi background produced just slightly below-average intelligence.
posted by luriete at 10:48 AM on June 3, 2005

'I hired a goy lawyer. It's like going to a straight hairdresser.'
posted by matteo at 10:48 AM on June 3, 2005

GrammarMoses : "Then that would be some pretty strong evidence of adaptive intelligence."

I don't understand the term 'adaptive intelligence', but I suppose it means intelligence that can be improved via adaptation? If so, not really. Doesn't take much more than average intelligence to notice that you're good at A, OK at B, and bad at C, and that's it hard for you to become good at B or C, and hence should concentrate on A.
posted by Gyan at 10:49 AM on June 3, 2005

Then how do you explain the irish?
The Irish had a country of their own--they weren't repeatedly invited into, say, France, and then thrown out a hundred years later, then invited back again by a new king another 50 years later, then thrown out again, etc.
posted by amberglow at 10:49 AM on June 3, 2005

Seems to me that if the Ashkenazi Jewish population married only within that population, and selected their marriages based on desirable traits, then they were obviously engaged in a human analogue of livestock breeding.

If you can breed dogs for docility, cows for milk output, chickens for egg-laying capacity, then why the heck not breed humans for intelligence?

Good on 'em. Our western society could do a helluva lot better were it breeding based on desirable characteristics. Instead, it often seems the people who breed the most are those who are least desirable.

(Oh, I'm so sure that's going to cause a flamewar. Good thing I didn't mention trailer parks! And, of course, using the term "breeding" is going to set someone off.)
posted by five fresh fish at 10:49 AM on June 3, 2005

When you can't own land, which was the case for the majority of our existence in Europe, you have to develop other skills--transportable ones.

We've always valued intelligence and education--we were educating ourselves throughout history--that wasn't true at all for the majority of Christians in Europe--education was rare until just recently.
posted by amberglow at 10:51 AM on June 3, 2005

I've always believed that the opposite effect was true for European Christians...send the smart kids to the seminary and the convent, and keep the dumb ones at home where they can breed.
posted by paul_smatatoes at 10:54 AM on June 3, 2005

The Irish had a country of their own--

Controlled by a hostile outside authority and plauged by starvation, corruption and persecution. But I was making a joke: if smarts are what help you survive persecution, then how did us Irish survive [rimshot]? But I failed since I'm not too bright. Hopefully my ashkenazi better half will help our children do better...
posted by jonmc at 10:54 AM on June 3, 2005

*had a ashkenazi better half*
*walks around halfless*
posted by schyler523 at 11:00 AM on June 3, 2005

I personally think differences in race are not genetic, but cultural

yep, many of of the differences are.

i think people also overlook the "10,000 hour" rule when speaking of achievments in both academics and athletics. if you train at something, whether it's book learnin' or putting a little white ball in a cup using a glorified stick, for 10,000 hours, chances are you're going to be outstanding at it.

on preview: But I was making a joke: if smarts are what help you survive persecution, then how did us Irish survive [rimshot]?

same for us blacks! well, i guess with your peeps it was alcohol, for us it was gettin' jiggy.
posted by lord_wolf at 11:02 AM on June 3, 2005

The notion that certain subgroups of the population have exceptional abilities when compared to the general population should not be surprising.

The notion that there is a genetic basis for these exceptional abilities is similarly not surprising.

This only becomes disconcerting in post-Enlightenment political structures since such structures tend to be formed on the basis that all persons are "equal" in the context of the political structure.
posted by mygoditsbob at 11:05 AM on June 3, 2005

The problem with these types of theories is that in this modern world, very few of us are pure anything. Most of us are mutts. Both Matt and jonmc have admitted to being part Jew.

This sets up a self-fulfilling prophecy type thing. As most people here know, I identify myself as Mexican. But what does that mean? More specifically, my father's line is mostly Mexican Indian with a smattering of French. My mother, on the other hand, comes from a family that has only been in Mexico for a generation or so, having come over directly from Spain. Oh, and it appears that they were Sephardic Jews.

When I told this more detailed family history to a Jewish friend of mine, their reaction was to nod smugly and proclaim "Ah. That explains why you are so smart. You are Jewish!"

To me, this doesn't seem like a productive way to approach things.
posted by vacapinta at 11:05 AM on June 3, 2005

schuyler: now I feel bad.

Come, let's hit the jug and get jiggy, with me and lord wolf.

Both Matt and jonmc have admitted to being part Jew.

By better half, I meant mrs. jonmc who is 1/2 ashkenazi. I'm a Goy Wonder, myself.
posted by jonmc at 11:08 AM on June 3, 2005

jonmc: no reason to feel bad...no...wait -- Now i blame you, you're right, it IS your fault...hand me that jug.

*sigh*
*guzzle*
Hic!

thath sthbetter...
posted by schyler523 at 11:18 AM on June 3, 2005

I was extremely dubious about this study before I read it, since I've always attributed the statistical differences to cultural ones (higher emphasis on the importance of education, certain careers, etc.)

But the paper actually makes a very convincing argument. I suggest people read it before they argue against it. It really makes some very good points.

If it matters, another Ashkenazi here.
posted by kyrademon at 11:19 AM on June 3, 2005

Both Matt and jonmc have admitted to being part Jew.

Admitted? That strikes me as an odd way to describe it.
posted by five fresh fish at 11:21 AM on June 3, 2005

When I told this more detailed family history to a Jewish friend of mine, their reaction was to nod smugly and proclaim "Ah. That explains why you are so smart. You are Jewish!"

You're friends with this asshat? Are you sure he wasn't making a joke?
posted by Marquis at 11:23 AM on June 3, 2005

Both Matt and jonmc have admitted confessed to being part Jew.

There. That's better.
posted by iron chef morimoto at 11:35 AM on June 3, 2005

Actually they don't really say that the diseases caused the greater intelligence at all--from Page 31---
Our general hypothesis is that high IQ test scores of Ashkenazim, along with their unusual pattern of abilities, are a product of natural selection, stemming from their occupation of an unusual social niche. All the required preconditions–low inward gene flow and unusually high reproductive reward for certain cognitive skills, over a long enough period–did exist. These preconditions are both necessary and sufficient, so such a selective process would almost inevitably have this kind of result. The pattern of high achievement among Ashkenazi Jews and the observed psychometric results are certainly consistent with this hypothesis.
Our more specific prediction is that some or most of the characteristic Ashkenazi genetic diseases are by-byproducts of this strong selection for IQ. ...
posted by amberglow at 11:42 AM on June 3, 2005

And relying on IQ test scores--not a true or full measure of intelligence--is shoddy.
posted by amberglow at 11:45 AM on June 3, 2005

this is kinda partially why some of us bridle at these sorts of theories, i think.
posted by amberglow at 11:49 AM on June 3, 2005

fff: Admitted? That strikes me as an odd way to describe it.

Well, that's your problem, not mine. I use "admitted" in the sense of making a revelation of something that may not otherwise be known. As I did just last week.
posted by vacapinta at 12:02 PM on June 3, 2005

amberglow, go back to page 20 where they at least imply that the diseases could be causative of higher intelligence.
posted by caddis at 12:05 PM on June 3, 2005

I always assumed the explanation for the Irish was they were invaded by the English who introduced the wheelbarrow and taught them to walk upright.
posted by warbaby at 12:09 PM on June 3, 2005

Oh, and did I mention the French? Never buy a used war or a used canal from the French.

*rimshot*
posted by warbaby at 12:18 PM on June 3, 2005

Marquis: You're friends with this asshat? Are you sure he wasn't making a joke?

Well, she was making a joke. But the thing about jokes is that they also sometimes reveal an attitude which is one of the reasons it disturbed me. Even presented as a joke, I took it as a slight to my Mexican heritage. It also raised questions such as: What about my brother, who shares the same heritage but is less "conventionally" smart? Anyways...starting to regret I brought it up, except as an anecdote about how we start getting into dangerous territory when we start making generalizations about people.
posted by vacapinta at 12:18 PM on June 3, 2005

Vacapinta, I had a similar experience with a college professor. I was the only one of his advisees who didn't identify as a Jew, when we talked about our family histories as part of a class project his eyes lit up and suddenly I was in the clique. Maddening.

I think the bigger question here is, if intelligence is something that is passed down through the genes then why isn't our society more stratified?
posted by cali at 12:23 PM on June 3, 2005

Rosalind Franklin is my favorite female scientist and an Ashkenazi jew. Her work led directly to the discovery of the structure of DNA. Unfortunately, Ashkenazi jews also have an unusually high incidence of mutations in the BRCA genes, and she died of cancer before she could be awarded the Nobel Prize. Did her high intelligence come at a price? Genetic homogeneity can be a dangerous thing...
posted by sacrilicious at 12:26 PM on June 3, 2005

There are no public outcries when scientists find that Ashkenazi Jews are more likely to suffer from Tay-Sachs Disease (caused by double recessive alleles), but when they find evidence for natural selection's role in their IQ, suddenly it's a whole different ballgame.

Yes, that's right. High IQ is not caused by double recessive alleles, or any other single factor. The development of the brain is very far from fully understood. (And Gladwell's audition-behind-the-curtain example has caused me to be very, very skeptical of this whole line of thinking.)
posted by Tlogmer at 12:30 PM on June 3, 2005

Excellent first post, Jason, and despite escabeche's dire predictions, it seems to have developed into a decent discussion, too.

/flexes mighty Ashkenazi brain
posted by Faint of Butt at 12:37 PM on June 3, 2005

I'm confused, and have what may be a stupid question.

Who are the Ashkenazi, specifically? I ask because a friend of mine says his family (who were German and Jewish) were not Ashkenazi (certainly not culturally - culturally they were German), and I had thought the Ashkenazi were the Jewish people of Eastern Europe, many of whom were not traders but farmers.

This has no bearing on the genetic discussion, I am just confused.
posted by jb at 12:43 PM on June 3, 2005

from page 20: ... The sphingolipid storage mutations were probably favored and became common because of natural selection, yet we don’t see them in adjacent populations. We suggest that this is because the social niche favoring intelligence was key, rather than geographic location... Second and most important, the sphingolipid mutations look like IQ boosters. ...
Who else has sphingolipid mutations in the world? Are we the only ones?

It just strikes me as really odd--"Boy, Jews are smart, aren't they? Why is that? What else do Jews have in common--I know! some genetic diseases!" And then they search for a connection between the two, when both can simply be explained by natural selection that favored intelligence, and that the intelligent got ahead, were more successful, and passed their smarts on more than idiots, while some of those smarties had disease-carrying genes, and our population was isolated--we inbred.

I also think it's incredibly odd that they ascribe it to a relatively recent era--dark ages/medieval times. We were not that bright before then? That doesn't ring true at all--education didn't suddenly start to be important in that era--creating a portable God and laws and systems that weren't dependent on land or place was key to our survival as a people. Scholarship was important and valued for far more than just 1000 years. I think they'd have to go further back to prove or disprove it all.

jb: Ashkenazi (most of the world's Jews are Ashkenazi)
posted by amberglow at 12:49 PM on June 3, 2005

The funny thing is, Ashekanzic Jews are the mutts of the Jewish world. Compared to Sephardim (Jews from Spain / North Africa), Mizrahim (Jews from the Middle East), Yemenites, etc., modern Ashekanzic Jews have probably the most genetic in-flow of all the Jewish groups and the most divergence from the probable ancient Judean standard.

Genetic testing shows that some of that in-flow came in via marriages where one partner was a convert to Judaism (usually the woman, since there is genetic evidence [via Y-chromosome DNA studies vs. mitochondrial DNA studies] that male Jewish lines were more likely to spread into new lands and marry local women than the reverse). And some came in via the Khazars, a Turkic people who converted to Judaism en masse so they could remain neutral between the nearby warring Christian and Muslim factions. Not to mention the occasional rape of Jewish women by your local Roman soldier, Viking, Cossack, or other bad guy, which brought in a little genetic diversity too. In short, if you do Y-chromosome and mtDNA genetic tests on 100 Ashkenazic Jews and 100 Sephardic Jews, the Sephardim should show less genetic in-flow and more closely align with their Judean ancestors*, while a decent percentage of Ashkenazim will have significant amounts of DNA from the local groups.

To be clear, Ashkenazic Jews on average still diverge quite a lot from the local European populations, though--see the graph on page #6 from this paper [PDF]--and on average they still genetically match up with Middle Eastern non-Jews more closely than they do European non-Jews. And the #1 most popular mtDNA haplogroup for Ashkenazic Jews is haplogroup K, which is rarely found in non-Jews, showing evidence that this was a pretty isolated inbred community, as Cochran et al would like us to think. But Cochran seems to ignore that the #2 most popular mtDNA haplogroup for Ashkenazic Jews is haplogroup H, which is also what 50% of Europeans and 70% of Brits/Scots/Irish/Welsh have! Judaism may be matrilineal, but quite a few of the Jewish mom's back in the very early history of European Jewry were local frauleins, femmes, and babas.**

So if Cochran et al are arguing that Ashkenazic smarts are due to heavy inbreeding among Jews in medieval Europe, they don't really seem to address the fact that the inbreeding took place among a group that was already somewhat admixed--and remains so to this day. I don't doubt that there were economic pressures to be smart and nimble (and even a little neurotic), but to say that these actually drove evolution itself over a paltry 1000-year period, especially for a group that already had some genetic mixing with the neighbors, is pushing things a bit much. Still, it is odd how the prevalent Ashkenazic genetic diseases mostly seem to do with abnormal neuron growth.

* and modern day Palestinians and Kurds, as has been discussed in previous MetaFilter threads.

** and in my case, possibly, a Scottish lassie. 30,000-40,000 Scots were in Poland, especially Warsaw, in the 16th-18th Centuries, because Poland had relative religious freedom (i.e. weren't biased against non-Catholic Scots) and good trading opportunities for Scottish products, particularly wool and clothing. I can trace my mother's mother's mother's...mother's line back to a Ashkenazic Jewish woman born in Warsaw in 1800. I have (and thus she had) mitochondrial DNA haplogroup H, subgroup H2*. Thus, judging from people's ancestral results who are closely matched to me in genealogical/genetic databases online (i.e. lineages, timelines, and the actual mtDNA mutations themselves), it looks like circa 1500 I had a bonnie Highland ancestress, probably living in Warsaw as a trader or the daughter of a trader, who married a local mensch and became a yenta. I would make a joke about how being both Scottish and Jewish should make me twice as cheap!, but any cursory look at my credit card bills would show that not to be the case. :-)
posted by Asparagirl at 12:50 PM on June 3, 2005

The results of this study are not going to be dispositive because (and the authors recognize this around pages 29-30) the statistical inference that the genetic disorders are causative of increased intelligence can't be tested in the Ashkenazi population.

Settling that question will require finding other populations with some or all of the gentic distinctions and seeing if there is significant variation of intelligence among them that correlates to the genetic features.
posted by warbaby at 12:50 PM on June 3, 2005

most of the world's Jews are Ashkenazi

But, for the record, most of Israel's Jews are not. I think they're currently running 40% Ashkenazic, 60% Sephardic/Mizrahi/Falasha/Yemenite/other, with their version of Generation X being majority mixed-marriage among the groups.
posted by Asparagirl at 12:53 PM on June 3, 2005

This is an interesting inference from disease patterns. The clincher would be studies on children adopted out to families of different heritages and habits. It would also be best if neither the children nor the parents knew they were Jewish, and hence grew up with no set expectations.

Good luck setting up that experiment!

Re amberglow on IQ scores: sure, they're a crummy measure. But you can still see them as a proxy for certain traits (note the article specifically mentions verbal and arithmetical ability, both of which are probably well rewarded in intelligence tests). If there is a consistent pattern in the scores, it's still interesting.

My mighty Ashkenazi brain predicts an outbreak of neonazi propaganda claiming that Jews have been selectively breeding themselves to cheat Gentiles, and need to be held back to even up the playing field.
posted by i_am_joe's_spleen at 12:57 PM on June 3, 2005

Yes, that's right. High IQ is not caused by double recessive alleles, or any other single factor. The development of the brain is very far from fully understood. (And Gladwell's audition-behind-the-curtain example has caused me to be very, very skeptical of this whole line of thinking.)

Well, height isn't determined by any single gene either, and yet no one would dream of arguing that there isn't, on average, a height difference between Scandinavians and Japanese. Most people's dismissal of the notion that there could be racial differences in intelligence is based not on any scientific consideration but on politics: greater intelligence clearly predicts all sorts of positive outcomes, so there's tremendous resistance to the idea that IQ is determined at least in part by your race.

From a scientific standpoint (setting aside the politics) it'd be shocking if there weren't racial differences in intelligence. Different populations evolved in different ecological niches, some of which presumably selected for intelligence more heavily than others. Again, no one disputes that different environments could select for things like skin color or height. So why is it so shocking that there should be differential pressure on a trait as fundamental as intelligence?

Not to mention that the vast majority of available evidence clearly indicates that, within heterogeneous (i.e., mixed-race) samples, intelligence is primarily attributable to genetic causes (with estimates typically around 80%). Given that 'race' is really nothing more than an arbitrary clustering of particular genes, there's little reason to expect that the proportion of variance of between-race differences in intelligence is any less attributable to genetic causes. It's politically incorrect to state as much, certainly, but that has nothing to do with establishing scientific credibility.
posted by heavy water at 1:02 PM on June 3, 2005 [1 favorite]

It's sensational! It's provocative! It's taboo!

But what are we trying to achieve here?

Why is this untested hypothesis posted here, if not for the sensationalism and provocation?

We should be careful how we proceed down this path and ones like it. I know it's trendy and feels good to break the "P.C." taboo, but what will the consequences be? In the past, the consequences of similar ideas -- whose promoters included scientists and intellectuals -- were millions dead.

Let's say this hypothesis is true -- do we want to know? How will be benefit?
posted by guanxi at 1:05 PM on June 3, 2005

Aspara--i was always told there are more of us (and we're overwhelmingly Ashkenazi) in the Northeastern US alone than the entire Jewish population of Israel. Is that still true?

heavy water, i don't think any of us disagree on genetic components to intelligence in general--it's more the linking of these specific diseases to that as a rationale.
posted by amberglow at 1:07 PM on June 3, 2005

interesting stuff, Asparagirl, thanks

Not to mention the occasional rape of Jewish women by your local Roman soldier,

in fact old, noncanonical (of course) traditions did indicate that Mary herself was raped by a Roman soldier named Pantera, thus giving birth to Jesus
posted by matteo at 1:10 PM on June 3, 2005

Asparagirl re speed of evolution: look at adult lactose tolerance in Europeans. From 1% in "normal" humans to 90% in Northern Europe in less than 10,000 years since the domestication of cattle, goats and sheep. So I'm quite prepared to believe that inbreeding + heavy selection can make a measurable effect to humans in 1000. The author isn't proposing a huge difference, either.
posted by i_am_joe's_spleen at 1:17 PM on June 3, 2005

Aspara--i was always told there are more of us (and we're overwhelmingly Ashkenazi) in the Northeastern US alone than the entire Jewish population of Israel. Is that still true?

Probably. There are estimtes of between 5.8 million and 6.15 million Jews in the US, but only 4 or 5 million in Israel. There are 1.4 million Jews in NYC (as of 2004), versus 1.15 million Jews in Tel Aviv (as of 2002). The US Jewish population is pretty stable, though, because a whopping 40-50% of US Jewish marriages are intermarriages, where the children will most likely not carry on the religion, but the Orthodox keep growing by leaps and bounds because they have many kids and intermarry rarely. So it all kind of balances out.
posted by Asparagirl at 1:32 PM on June 3, 2005

30,000-40,000 Scots were in Poland, especially Warsaw, in the 16th-18th Centuries

Your entire comment was interesting, Asparagirl, but this in particular fascinated me -- thanks!

I hadn't realized Ashkenazim were such a heavy majority; from here:

By the end of the 19th century, as a result of Russian persecution, there was massive Ashkenazi emigration from Eastern Europe to other areas of Europe, Australia, South Africa, the United States and Israel. Ashkenazim outnumbered Sephardim everywhere except North Africa, Italy, the Middle East and parts of Asia. Before World War II, Ashkenazim comprised 90% of world Jewry.

The destruction of European Jewry in World War II reduced the number of Ashkenazim and, to some extent, their numeric superiority over Sephardim. The United States became the main center for Ashkenazi Jews.

posted by languagehat at 1:39 PM on June 3, 2005

The article is, at best, internally inconsistent. The author acknowledges the Flynn effect (preferring to pin it on increased school attendance) but go on to argue that "the current consensus is that variation in IQ reflects variation in the underlying biology rather than in the social environment."

I have a lot of problems with this statement.

(1) Huh? You just told me rising IQ scores are due to increasing school attendance. If school isn't part of the social environment what is?

(2) How do you explain a consistent 15-point IQ gap between blacks and whites in the US, Catholics and Protestants in Northern Ireland, and Koreans and Japanese in Japan if not via social environment?

(3) This statement is designed to sneak a poorly-defined "consensus" view into the argument. The consensus is that the heritability of g is between .5 and .8, period. But this statement makes it sound like the scientific community has gotten together and said "well! I guess nature wins over nurture, case closed!" This sort of rhetorical trick makes me doubt the reasoning behind the rest of the paper.
posted by lbergstr at 1:50 PM on June 3, 2005

They have uncovered our Mentat training. Now the Butlerian Jihad must begin...
posted by PenDevil at 1:54 PM on June 3, 2005

languagehat- yeah, the Scots-in-Poland thing is yet another subject I've been meaning to post a FPP about one of these days...you'd be surprised at the wacky cross-cultural fertilization that happened there. There's this scanned-in book from 1915, which has some details, or this book, which also covers the history of Scots in the Baltic states.

By the way, Cochran, the author of the paper, sometimes posts and sometimes comments at the genetics and bio-engineering blog Gene Expression. I found this post of his from August, 2004 about the problems in trying to get his paper published to be pretty funny.
posted by Asparagirl at 2:45 PM on June 3, 2005

I read something interesting on Jews and intelligence a while ago.

Anyway... the argument went that for over five thousand years, Jews have had to be rather more highly educated than was the norm until the past couple hundred years. Part of the religious aspect of Judaism is that you must be able to read the Torah. Reading, up until relatively recently, was an enormous investment in time and energy, time that the person in question wasn't providing for the family. The benefit, of course, is that the Jewish community at large, and any community which had a Jewish presence, therefore had access to a huge skill set that most other people (unless they had a lot of money) simply did not. When you add in the Hebrew language's facility for math (every letter in the alephbeth has a numerical value; 1-9, 10-90, 100-900; no concept of zero, interestingly), the skill set becomes larger, and focused much more on brainpower than bodypower.

So it would seem logical that a community which has already self-selected to be good at such things would place an emphasis, as noted above, on doing those things. Moreover, the more intelligent you are (in a system where brainpower is more important than bodypower), the more likely you are to mate, thus ensuring those genes and traits are more likely to be passed on.
posted by dirtynumbangelboy at 4:41 PM on June 3, 2005

I was just reading about this phenomenon -- in the context of chess. But the theory went that Jewish intellectual life (memory work, pattern analysis) lent itself well to the deep study of chess. Not an argument that I find hard to believe, without the need to resort to genetics.
posted by dreamsign at 4:45 PM on June 3, 2005

heavy water: Well, height isn't determined by any single gene either, and yet no one would dream of arguing that there isn't, on average, a height difference between Scandinavians and Japanese.

No one would dream of arguing that different populations do not have different heights, but people do argue that the reasons for the differences are not genetic:

"Height variations within a population are largely genetic, but height variations between populations are mostly environmental, anthropometric history suggests."

See: The Height Gap by Burkhard Bilger in the New Yorker
posted by Quinbus Flestrin at 4:46 PM on June 3, 2005

(1) Huh? You just told me rising IQ scores are due to increasing school attendance. If school isn't part of the social environment what is?

lbergstr, the Flynn effect doesn't contradict the established finding that intelligence is largely hereditary. What it does do is highlight the fact that genes are not expressed in a vacuum; they require interaction with the environment. Altering the environment can effect a net change in a variable, but that doesn't tell you anything about the underlying cause. It's entirely consistent (and based on existing data, highly probable) that environmental changes lead to changes in intelligence via the differential expression of underlying genetic predisposition.

By way of analogy, consider height. Over the last several hundred years, the height of the average human being has increased by several inches. The change has been attributed primarily to dietary (i.e., environmental) factors. Yet you'd be crazy to conclude on that account that variation in height isn't largely genetic. The contribution of diet is very small compared to genetic factors: you can't add 5" to your kid by feeding them broccoli (despite what some parents say); conversely, even in conditions of uniform malnutrition, there are huge differences in people's heights. The same holds true for intelligence. A gradual increase demonstrates that the environment has some influence (and no one's denying that!), but that doesn't speak to the fact that the vast majority of variance is accounted for by genetic factors.

(2) How do you explain a consistent 15-point IQ gap between blacks and whites in the US, Catholics and Protestants in Northern Ireland, and Koreans and Japanese in Japan if not via social environment?

Presumably as a result of genetic differences, right? That's the contention. The fact that you don't like the thought that genes are responsible for such large differences has no bearing on whether it's true or not.

(3) This statement is designed to sneak a poorly-defined "consensus" view into the argument. The consensus is that the heritability of g is between .5 and .8, period. But this statement makes it sound like the scientific community has gotten together and said "well! I guess nature wins over nurture, case closed!" This sort of rhetorical trick makes me doubt the reasoning behind the rest of the paper.

Well there pretty much is a consensus among researchers that the genetic contribution to intelligence is larger than the environmental contribution. I hesitate to say the case is closed (it's never safe to say that), but I'd suggest the main reason the topic remains so controversial is that most lay people are not really willing to accept what the (consensual) science says. Very few large behavioral genetic studies of intelligence have failed to attribute the majority of variance in intelligence to genetic factors. But scientific consensus is, unfortunately, no match for deeply-held lay intuition.
posted by heavy water at 5:07 PM on June 3, 2005

"Height variations within a population are largely genetic, but height variations between populations are mostly environmental, anthropometric history suggests."

Quinbus, I enjoyed reading the article you point to, but it certainly doesn't amount to a quantitative case for an environmental source of height differences. A difficulty with the kind of research it talks about (based on tracking heights in different groups over time) is that establishing that there are changes in height over time doesn't tell you anything about the causes of those changes. The fact that height changes track dietary changes is just as easily attributable to gene-environment interactions (i.e., some people are more susceptible to dietary changes than others) as it is to a solely environmental explanation. In contrast, the available behavioral genetic data I've seen (that actually gets quantitative estimates of the contributions) suggests that height and BMI are largely heritable even when you look across cultures.

That said, I'm certainly not suggesting that none of the variance in height (or intelligence) is due to environmental cause. Nor am I making the positive claim that racial differences in intelligence or height intelligence or height are due to genetic causes. My point is that, if it were possible to remove politics from the equation, there would be no good scientific reason not to suspect that between-group differences are in large part due to genetic factors.
posted by heavy water at 5:44 PM on June 3, 2005

The fact that height changes track dietary changes is just as easily attributable to gene-environment interactions (i.e., some people are more susceptible to dietary changes than others) as it is to a solely environmental explanation.

I don't understand this. Isn't all development by definition a gene-environment interaction? Humans and their genes cannot exist independent of an environment, which is largely why teasing out their relative importance is difficult.

The point about the height example compared to intelligence is that at first it seems obvious that the difference in heights of the "races" has a genetic cause, except that the differences change radically with environment, so what was at once seemed obvious becomes less clear. I agree with you that it would be foolish to categorically deny the possibility of the genetic role for differences in height or intelligence, but even with genetic differences taken into account there is reason to be careful in assuming that "between-group differences are in large part due to genetic factors."
posted by Quinbus Flestrin at 9:20 PM on June 3, 2005

I don't understand this. Isn't all development by definition a gene-environment interaction? Humans and their genes cannot exist independent of an environment, which is largely why teasing out their relative importance is difficult.

Yes and no. I think you're using the term 'interaction' in an every-day sense to denote the fact that it's necessary for both to be present. I'm using it in a technical sense to denote overadditive effects that can't be accounted for solely by a change in either environment or genetic makeup.

Here's an illustration. A change in height that's attributable solely to environment (in a technical sense; i.e., what's called a 'main' effect) would be if it turned out that increasing the amount of vegetables in people's diet increases height uniformly for everyone. Conversely, a main effect of genes would be if manipulating a particular allele would cause an increase in height for everyone irrespective of environment.

A gene-environment interaction occurs when changes in the dependent variable (e.g., height) can't be accounted for just by changes in genes or just by changes in height. So, for example, if it turns out that people from one genetic background are highly sensitive to, say, vitamin A deficiency whereas people from another are not, that would constitute an interaction. The point being that if you had just observed that, averaged across all cultures, people are shorter when they don't get enough vitamin A, that would obscure the interaction and you might erroneously conclude that vitamin A by itself increases height.

This isn't an important point if the only claim you want to make is "well, it's both nurture and nature". Clearly, there has to be some element of both. But once you actually get down to quantifyiing the contribution of each, it becomes important to take into account the kinds of effects I'm talking about. So yes, you're right in that all development requires that we have both genes and environment. But science allows us to go beyond that basic observation and actually slap numbers on the contribution of genes and environment to particular behaviors. And again, when you approach things from that perspective, it turns out that the majority (but again, not all) of the variance in height both between- and within- (though more so for the latter) is accounted for by genes.
posted by heavy water at 10:14 PM on June 3, 2005

Some writer in France stirred up a big debate a few years ago with this theory: In medieval Europe about 10% of the population of Christians were either priests, monks, or nuns. This 10% would have been the top thinkers, the cream of their genetic pool - literacy was confined to them. And so smart people were basically pulled out of the genetic pool for about eight hundred years. (This may explain the French adoration of Jerry Lewis.)

Jews, on the other hand promoted learning - promising yeshiva students with virtually no business experience were considered the right match for a prosperous merchant's daughter in a marriage. So the most prosperous were matched with the best scholars.

Sephardim, residing in Muslim kingdoms, did not become stereotyped as much smarter than the general population because Islam didn't force celibacy on it's most talented thinkers.
posted by zaelic at 6:52 AM on June 4, 2005

So then, zaelic, it's not that we're smarter, but that Christians inadvertently dumbed themselves down? (and, i'd have to add, from what i've read and learned, many nunneries weren't as chaste as supposed--especially the ones full of higher-born women)
posted by amberglow at 8:56 AM on June 4, 2005

"This paper elaborates the hypothesis that the unique demography and sociology of Ashkenazim in medieval Europe selected for intelligence. Ashkenazi literacy, economic specialization, and closure to inward gene flow led to a social environment in which there was high fitness payoff to intelligence, specifically verbal and mathematical intelligence but not spatial ability."

I've wondered along these lines. But I like Zaelic's theory too.

My wife's an Ashkenazi Cohane. Woo hoo. Her brother is a highly paid academic statistician. She's an art teacher and a potter.

Talk about sexual occupational dimorphism in one family.


This theme also raises another issue - the relative benefits and costs of inbreeding.

Everyone in my wife's family has a bad back and various odd ailments. Marraiges to Goyyim have produced spectacular results though. My wife's grandmother has made some rather pointed comments - in the company of her rather robust and well-formed Jew-Goy grandchildren - about the need for a bit of "fresh blood" in the famly line.

Well, I'm off to flex my Celtic brawn, visual-spatial prowess, and impulsive adventurism. (I'm cleaning my basement and hauling drek to the dump ). My people are known for tossing huge logs and rocks around, singing morose songs, writing poetry, and drinking heavily. They are also handy in a tight spot, in battle.

I'm actually painted myself blue once or twice, but that was for artistic reasons and not for Druidic ritual sacrific involving large wicker baskets or the worship of sacred trees.

Honest. I swear.

Did I also mention that Celts, under stress, slough off Christianit , to devolve into savage pagans ?

Anyway, back to theories on Ashkenazi intelligence.....
posted by troutfishing at 9:58 AM on June 4, 2005

Also, Celts, being impulsive, are known to neglect spell-checking.

That, too, is genetic.
posted by troutfishing at 9:59 AM on June 4, 2005