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Slightly Off Topic: Ashkenazic Intelligence-disease?

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  • Slightly Off Topic: Ashkenazic Intelligence-disease?

    Researchers Say Intelligence and Diseases May Be Linked in Ashkenazic Genes
    By NICHOLAS WADE

    A team of scientists at the University of Utah has proposed that the unusual pattern of genetic diseases seen among Jews of central or northern European origin, or Ashkenazim, is the result of natural selection for enhanced intellectual ability.


    The selective force was the restriction of Ashkenazim in medieval Europe to occupations that required more than usual mental agility, the researchers say in a paper that has been accepted by the Journal of Biosocial Science, published by Cambridge University Press in England.

    The hypothesis advanced by the Utah researchers has drawn a mixed reaction among scientists, some of whom dismissed it as extremely implausible, while others said they had made an interesting case, although one liable to raise many hackles.

    "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."

    "Absolutely anything in human biology that is interesting is going to be controversial," said one of the report's authors, Dr. Henry Harpending, an anthropologist and a member of the National Academy of Sciences.

    He and two colleagues at the University of Utah, Gregory Cochran and Jason Hardy, see the pattern of genetic disease among the Ashkenazi Jewish population as reminiscent of blood disorders like sickle cell anemia that occur in populations exposed to malaria, a disease that is only 5,000 years old.

    In both cases, the Utah researchers argue, evolution has had to counter a sudden threat by favoring any mutation that protected against it, whatever the side effects. Ashkenazic diseases like Tay-Sachs, they say, are a side effect of genes that promote intelligence.

    The explanation that the Ashkenazic disease genes must have some hidden value has long been accepted by other researchers, but no one could find a convincing infectious disease or other threat to which the Ashkenazic genetic ailments might confer protection.

    A second suggestion, wrote Dr. Jared Diamond of the University of California, Los Angeles, in a 1994 article, "is selection in Jews for the intelligence putatively required to survive recurrent persecution, and also to make a living by commerce, because Jews were barred from the agricultural jobs available to the non-Jewish population."

    The Utah researchers have built on this idea, arguing that for some 900 years Jews in Europe were restricted to managerial occupations, which were intellectually demanding, that those who were more successful also left more offspring, and that there was time in this period for the intelligence of the Ashkenazi population as a whole to become appreciably enhanced.

    But the Utah researchers' analysis comes at a time when some geneticists have suggested natural selection is not the reason for the Ashkenazic diseases after all. Two years ago, Dr. Neil Risch, a geneticist now at the University of California, San Francisco, proposed a different genetic mechanism known as a founder effect, which occurs when a population is reduced for a time.

    He found that all the Ashkenazic diseases had similar properties, including having arisen within the last 1,100 years. Therefore they had all arisen through the same cause, he argued, which must be founder effects, because it was unlikely that all could be due to natural selection. Last year, Dr. Montgomery Slatkin of the University of California, Berkeley, came to much the same conclusion for different reasons.

    The Utah team agrees with Dr. Risch that the diseases all arose in historical times from the same cause but say natural selection is more likely because none of the non-disease Ashkenazic genes they tested showed any sign of a founder effect. They say the clustering of four of the diseases in the same biochemical pathway could only have arisen under the influence of natural selection, and calculate that the odds of a founder effect producing such a cluster are vanishingly low.


    The four diseases, all of which are caused by mutations that affect the cell's management of chemicals known as sphingolipids, are Tay-Sachs, Niemann-Pick, Gaucher, and mucolipidosis type IV. A second cluster of diseases affects repair of DNA.

    Turning to the possibility that some infection was the cause of the selective effect, the Utah researchers noted that Ashkenazim and Europeans lived together in the same cities and were exposed to the same microbes. If disease were the agent of selection, the Utah team argues, the European population would have developed a similar genetic response.

    Ashkenazi Jews occupied a different social niche from their European hosts, and that is where any selective effect must have operated, the Utah researchers say. From A.D. 800, when the Ashkenazi presence in Europe is first recorded, to about 1700, Ashkenazi Jews held a restricted range of occupations, which required considerable intellectual acumen. In France, most were moneylenders by A.D. 1100. Expelled from France in 1394, and from parts of Germany in the 15th century, they moved eastward and were employed by Polish rulers first as moneylenders and then as agents who paid a large tax to a noble and then tried to collect the amount, at a profit, from the peasantry. After 1700, the occupational restrictions on Jews were eased.

    As to how the disease mutations might affect intelligence, the Utah researchers cite evidence that the sphingolipid disorders promote the growth and interconnection of brain cells. Mutations in the DNA repair genes, involved in second cluster of Ashkenazic diseases, may also unleash growth of neurons.

    In describing what they see as the result of the Ashkenazic mutations, the researchers cite the fact that Ashkenazi Jews make up 3 percent of the American population but won 27 percent of its Nobel prizes, and account for more than half of world chess champions. They say that the reason for this unusual record may be that differences in Ashkenazic and northern European I.Q. are not large at the average, where most people fall, but become more noticeable at the extremes; for people with an I.Q. over 140, the proportion is 4 per 1,000 among northern Europeans but 23 per 1,000 with Ashkenazim.

    The Utah researchers describe their proposal as a hypothesis. Unlike many speculations, it makes a testable prediction: that people who carry one of the sphingolipid or other Ashkenazic disease mutations should do better than average on I.Q. tests.

    The researchers have identified two reasonably well accepted issues, the puzzling pattern of diseases inherited by the Ashkenazi population and the population's general intellectual achievement. But in trying to draw a link between them they have crossed some fiercely disputed academic territories, including whether I.Q. scores are a true measure of intelligence and the extent to which intelligence can be inherited.

    The authors "make pretty much all of the classic mistakes in interpreting heritability," said Dr. Andrew Clark, a population geneticist at Cornell University, and the argument that the sphingolipid gene variants are associated with intelligence, he said, is "far-fetched."

    In addition, the genetic issue of natural selection versus founder effects is far from settled. Dr. Risch, whose research supports founder effects, said he was not persuaded by the Utah team's arguments. Dr. David Goldstein, a geneticist at Duke University who was not connected with either Dr. Risch's or the Utah study, was more open on the issue, saying Dr. Risch had made "quite a strong case" that founder effects could be the cause, but had not ruled out the possibility of selection.

    Dr. Slatkin, though favoring a founder effect over all, said he agreed with the Utah team that this would not account for the cluster of sphingolipid diseases.

    As for the Utah researchers' interpretation of Jewish medieval history, Paul Rose, professor of Jewish studies at Pennsylvania State University, said, "I think that some of their conclusions may be right though they still need a lot of work to be persuasive to historians and others."

    Dr. Gregory Cochran, the first author on the Utah team's paper and a physicist who took up biology, said he became interested in the subject upon learning that patients with a particular Ashkenazic disease known as torsion dystonia were told by their physicians that "the positive thing is that this makes you smart."

    "When you're in a hurry and have strong selection, you have a lot of genes with bad side effects," he said. The Ashkenazi Jewish population seemed to fit this pattern, he said, since they married only inside the community, making selection possible, and they had an urgent need for greater intelligence. Evolution had therefore selected every possible mutation that worked in this direction, despite their harmful side effects when inherited from both parents. "In a sense, I consider this a very boring paper since it raises no new principles of genetics," Dr. Cochran said.

  • #2
    okay some of you are wondering what this really got to with projects and this dna

    i wonder what the studys would show if they took into context people with obvious askenazi genetic conections who for whatever reason are not part of
    the comunity. now that we are getting some slight indication of these people .how does it apply?

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    • #3
      actually I was thinking the same thing. I think they are only testing self acknowledged Askenazi...not those who have Askenazi ancestory but not longer consider themselves Jews.

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      • #4
        At least one of the diseases found in the Ashkenazi community, Tay-Sachs, is also found among Acadians of southern Louisiana. Does anyone know if there is a genetic connection there?

        I read about a paper that suggested that a Jewish family was among the early Acadian settlers, but it didn't elaborate or name the couple.

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        • #5
          There is a connection between the Acadians/Cajuns and the Jews. Many of the Acadians that came to Nova Scotia were Huguenots that used to be Jews. It is a very complicated story, but the link is there.

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          • #6
            I've seen no proof of this claim that there were Jews among the early Acadians. Do you know of any?

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            • #7
              reference for article

              Hi - could you post a reference for the article discussed in the first post of this thread? Thanks. And if theres a website that goes to the text, that would be great also. It's possible the reference was included and I missed it.

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              • #8
                I googled using a phrase from the first post and got the article. Oddly, if one uses the url of the item one has to login.

                http://www.nytimes.com/2005/06/03/sc...gewanted=print

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                • #9
                  I have to admire the guys who put their names on that article, knowing what sort of accusations they were going to open themselves up to. Anyone remember the book "The Bell Curve," by Herrnstein and Murray?

                  This topic literally terrifies people, but it IS related to this FTDNA site, or at least the "deep ancestry" Genographic aspect of this site. Everyone walking down the street recognizes that there are different "kinds" of people who come from different places, and what we are learning from mtDNA and Y DNA is that this is the result of migrations of relatively small groups of people who were somewhat isolated (at least reproductivelyand usually geographically) from each other over thousands or even tens of thousands of years.

                  No one would ever contend that a draft horse and a race horse are equally capable of doing all horse things, and every dog lover "knows" that different breeds have different personalities--but we are "supposed" to be blind to human differences in that respect and operate under the assumption that different "kinds" of human are all exactly the same in all aspects of brain function, no matter what their bodies may look like and no matter that they are separated by many more generations of isolation than the dog or horse types are.

                  Part of this is a misunderstanding of what statistics means. A mean or a median does not indicate anything about an individual other than a statistical prediction that is either completely true or completely false for that individual. I think the error is that people understand papers like the one discussed here to imply that "all" Ashkenazi Jews are smarter than "all" other Europeans, and conversely for other groups that fare more poorly on intelligence tests. That is not what it says. It says only that there is a statistical skew in the data--this could either be a shift in the mean value of a normal distribution (bell curve) or a deviation from a normal distribution to an asymmetric one with a larger "tail" to the right. Such curves for all living humans would overlap extensively, and for any individual it is merely a matter of where he falls on the curve; there will be many, many "stupid" Ashkenazim and many, many "genius" Europeans; where the mean of their population falls does not affect these individuals in any way. Actually, it is really quite remarkable how similar we all are in spite of what we are learning here from the DNA.

                  It will be interesting to see what happens with this paper. I know I would not be eager to publish something like that...

                  Jeff Schweitzer

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                  • #10
                    1/2 of my 52 12/12 matches are askenzi with strong ties to israel

                    and i have 24/25 and 15 matches which are with people whose family traditions are that people were forced to convert to christianity from Judaism

                    so i think somehow i to have that kind of link to askenazis

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                    • #11
                      Weren't the Irish among the ten lost tribes Jim??

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                      • #12
                        But more seriously, to answer your question and Rasfarengi's, Jim, no doubt at all that there are many Europeans with some Ashkenazi ancestry. I do not believe that this is relevant to the paper. Unless you know for a fact that a parent or grandparent was Ashkenazi, giving you a significant percentage of Ashkenazi ancestry, you, and most others who may be the descendants of converts forced or voluntary, likely have at most a small percentage of Ashkenazi ancestry; the Y chromosome is what--2% of your genome?--and you are no longer part of that particular reproductively isolated community. There was no doubt a good degree of conversion INTO the Ashkenazi community prior to about 1000 AD, and not again until the last 50 years or so; there has ALWAYS been a slow trickle of converts OUT of the Ashkenazi community, but there were never huge forced mass conversions as happened in 1492 to the Sephardic community in Spain. For the 1000 years or so in which the purported evolutionary pressures were brought to bear on the community, therefore, it was more or less completely reproductively isolated. The outward trickle would have then intermarried with the surrounding community (as opposed to the Marranos or other forced Sephardic converts who in some instances retained a community identity) and there would thus be no reason to include someone in the study simply because his Y chromosome was ultimately from an Ashkenazi progenitor.

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                        • #13
                          Originally posted by dentate
                          Weren't the Irish among the ten lost tribes Jim??
                          all of western europeans nations are are keltoi

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                          • #14
                            Originally posted by dentate
                            But more seriously, to answer your question and Rasfarengi's, Jim, no doubt at all that there are many Europeans with some Ashkenazi ancestry. I do not believe that this is relevant to the paper. Unless you know for a fact that a parent or grandparent was Ashkenazi, giving you a significant percentage of Ashkenazi ancestry, you, and most others who may be the descendants of converts forced or voluntary, likely have at most a small percentage of Ashkenazi ancestry; the Y chromosome is what--2% of your genome?--and you are no longer part of that particular reproductively isolated community. There was no doubt a good degree of conversion INTO the Ashkenazi community prior to about 1000 AD, and not again until the last 50 years or so; there has ALWAYS been a slow trickle of converts OUT of the Ashkenazi community, but there were never huge forced mass conversions as happened in 1492 to the Sephardic community in Spain. For the 1000 years or so in which the purported evolutionary pressures were brought to bear on the community, therefore, it was more or less completely reproductively isolated. The outward trickle would have then intermarried with the surrounding community (as opposed to the Marranos or other forced Sephardic converts who in some instances retained a community identity) and there would thus be no reason to include someone in the study simply because his Y chromosome was ultimately from an Ashkenazi progenitor.
                            what my point is when you count those who come from that comunity but haven't lived it for 600 or so years .my guess is that the figure would mediate.
                            that less disease and intellegence would be appearent
                            in boston an irish girl sued for the right to attend boston latin because of revere discrimination she won. one reporter commented people think this means more irish will be admited . the comentor said thats wrong it will mean boston latin will be all Chinese. why because of intelegence yeah but a fmaily unit that stresses accomplishement .
                            my guess is the askenazis are just that and evolution and founder are both working but more a system that a group has adopted and found to work. thus perpetuating it
                            if i am askenzi or shepahdic why dont i have those diseases in my family? 600 yrs would be too quick for evolution maybe the bulldog shephardics became christian and the poodles remained.lol

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                            • #15
                              You don't have the diseases in your family because the genes for those diseases are not on the Y chromosome and are not linked to the markers we are using here as "tracers." Other than suggesting or refuting your relationship to another individual, these mtDNA and NRY markers are mainly useful when looked at for their frequencies in a population, to infer that population's relationship to others.

                              If your Y chromosome is from an Ashkenazi source, then that same male ancestor would have contributed to your autosomal genome as well, but the contribution would be such a small fraction that it is statistically unlikely that you would have inherited the disease genes. They may be out there somewhere, maybe in you or maybe others of his descendants, but there would be no way to identify who has inherited them from an Ashkenazi ancestor based on mtDNA or NRY data. Harmful disease genes that are not subject to positive selective pressure on the heterozygotes would be expected eventually to vanish from the population.

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