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A theory of Ashkenazi genius: intelligence and mental illness
A new spin on Galton's triple event of genius
I want to put together a theory to explain a putative phenomenon: Ashkenazi Jews have more geniuses relative to non-Jewish Europeans (gentiles) than one would expect based on their average intelligence of about 110 IQ. This hasn't been strictly shown mathematically, but I think it is true. We can do a rough estimate using the interactive tail effects tool here. We fill in the approximate number of European Americans and Ashkenazi Americans. I used 204 and 5.5 million. Then we fill in the approximate mean and SDs of IQ, I used 100/15, 110/15. Then we have to guess at a threshold for resulting in a genius of some sort. It is well knowing that there is more to genius than simply being very smart. The SMPY and Terman samples didn't produce many geniuses despite sky-high IQs, the latter even missed two Nobel prize winners. But let's ignore this, and say the threshold is 140. Using that, we get this result:
So among the Americans who are regular Europeans or Ashkenazis and who have 140+ IQ, 86% are gentiles, and so 14% are Ashkenazis. However, looking at US Nobel prize winners, Ashkenazis appear to be about 33%. Thus, according to our crude modeling, there's something like twice as many Ashkenazi geniuses than expected, some other factor is at play making them more likely to become geniuses. Mind you these numbers are all approximative.
I submit that this other factor is mental illness, or what we now a days would call the general factor of psychopathology, or P factor. You can think of this as an overall index of a person's craziness. There is a long running interest in genius and madness. The saying goes that the only difference between them is success. That is true enough. Many researchers have looked over the family histories of historical geniuses and they do have elevated rates of mental illness, both in themselves and in their relatives. For example, Simonton in his Genius 101 book from 2009, summarizes 6 lines of evidence:
"First, genius does seem “near ally’d” with madness. This alliance holds in the sense that various indicators and symptoms of psychopathology appear to occur at a higher rate and intensity among geniuses than in the general population.
Second, the greater the magnitude of genius, the more likely it is that these signs will appear. Yet the level of psychopathology seen in even the greatest geniuses remains below the level characteristic of those who would be considered indisputably insane. In fact, works of genius do not appear when a genius has succumbed to complete madness. So “thin Partitions do their Bounds divide.”
Third, some psychopathologies appear more frequently, with depression being the most common. Other syndromes, such as the paranoid schizophrenia of John Nash, are less common, albeit not impossible.
Fourth, family lineages that have higher than average rates of psychopathology will also feature higher than average rates of genius. Hence, even if a genius does not have a modicum of mental illness, someone in his or her family may be less fortunate. However normal Albert Einstein may or may not have been as an adult, it cannot be denied that his son Eduard succumbed to schizophrenia and had to be institutionalized.
Fifth, the rate and intensity of psychopathological symptoms varies across the diverse domains of achievement. In some domains, such as poetry, mental illness may run rampant, whereas in other domains, such as the natural sciences, mental illness will not be much more common than in the general population.
Sixth and last, any tendencies toward psychopathology are almost invariably counterbalanced by other personal traits that strengthen the individual’s response to any symptoms. Especially critical are a sharp intellect and strong willpower that prevent any crazy thoughts from becoming outlandish behaviors. The symptoms of pathology thereby become resources to be exploited rather than insecurities to be feared."
But what evidence is there really that Ashkenazis have more mental illness than gentiles? It's definitely sparse. It's a small group and it's often not identified aside from the regular Europeans (everybody is "White"). But there is a new exciting study that looked into this using medical records and genetics:
Caggiano, C., Boudaie, A., Shemirani, R., Petter, E., Chiu, A., Johnson, R., ... & Zaitlen, N. (2022). Health care utilization of fine-scale identity by descent clusters in a Los Angeles biobank. medRxiv.
An individual’s disease risk is affected by the populations that they belong to, due to shared genetics and shared environment. The study of fine-scale populations in clinical care will be important for reducing health disparities and for developing personalized treatments. In this work, we developed a novel health monitoring system, which leverages biobank data and electronic medical records from over 40,000 UCLA patients. Using identity by descent (IBD), we analyzed one type of fine-scale population, an IBD cluster. In total, we identified 376 IBD clusters, including clusters characterized by the presence of many significantly understudied communities, such as Lebanese Christians, Iranian Jews, Armenians, and Gujaratis. Our analyses identified thousands of novel associations between IBD clusters and clinical diagnoses, physician offices, utilization of specific medical specialties, pathogenic allele frequencies, and changes in diagnosis frequency over time. To enhance the impact of the research and engage the broader community, we provide a web portal to query our results: www.ibd.la
They used genetic cluster to calculate identity by descent (IBD), i.e., fractions of the genome that different populations share due to shared ancestors (recent-ish ones) and then used these to produce race groups. They got this clustering:
Due to the sample, there are some communities that are otherwise too small to find in national data that appear here, such as the two Iranian groups. It can be seen that the Iranian Jews and non-Jews are close together, likely due to historical intermarriage (gene flow). The same is seen for the European non-Jews and the Ashkenazis. Otherwise things look pretty normal. In terms of sampling, the patients also cluster by their co-ethnics geographically:
This is basically a map of Chinatown, Koreatown, Japantown, Telugutown, Egyptian Christian-town etc.
Visiting the website for the study allows us to compare the rates of diagnoses by these ethnic groups. Here's the comparison between Ashkenazis and regular Europeans:
Higher values more mean common in Ashkenazis. Here we see: eating disorder, obsessive-compulsive disorders, anxiety, phobic, dissociative orders, and psychogenic disorder. On the other hand, normal Europeans have more alcoholism seen as alcoholic liver damage and alcohol-related disorders. This exactly fits my stereotype. None of my Jewish friends are heavy drinkers, but many of them are kinda crazy. To test that this isn't just due to regular Europeans vs. everybody else, I tried some other comparisons. Here's regular Europeans vs. Japanese:
Japanese have more type 2 diabetes and all sorts of medical things, but none of the mental illness diagnoses show up either way. Here's Punjabi+Bengali, a south Asian cluster:
They also have elevated rates of various things, but not mental illness. Note that as the sample sizes go down, the model cannot detect small differences, as only the ones with p < .05 are shown. The Ashkenazi cluster is impressively large at over 5000.
Maybe this is just UCLA that attracts crazy Jews. What about some other datasets? I looked in the OKCupid study, and there's a question about "Are you Jewish?" and some questions about mental health. I didn't do a thorough study, but consider this question about having seen a therapist:
So 79% of American Jews in the sample say they have seen a therapist. This is higher than all the other groups, including the regular Europeans who are at 63%. These are all high numbers, I guess because people interpret the question broadly, as maybe having seen a school psychologist at some time in their life, or maybe family counseling. Maybe it's just that OKCupid users who fill out lots of questions are a very crazy bunch. Whatever the exact reason for the high numbers, the difference is large enough to care: about +25% on even such a simple survey question. Controlling for various obvious factors doesn't make this disappear:
Hard to read, but the Estimate shows the logits for each race/ethnic, using White European non-Jews as the reference. So Ashkenazis have a beta of 0.777, p < .001. This is controlling for age, gender, and question count on the website, as a measure of self-selection bias from spending a lot of time filling out survey questions. One can further control for more things like state of residence, but this will also introduce more bias insofar as this is self-caused. Without controls, the beta is 0.81, so it was hardly affected by the controls. If one adds a control for state of residence, beta is 0.77, p < .001.
Good enough for now: two independent datasets show Ashkenazi are higher in mental illness in America. American Jews are mainly Ashkenazi, OKCupid doesn't distinguish between them, so I am assuming these are Ashkenazis.
One final piece of intriguing evidence regarding mental illness and intelligence:
Kendler, K. S., Ohlsson, H., Sundquist, J., & Sundquist, K. (2015). IQ and schizophrenia in a Swedish national sample: their causal relationship and the interaction of IQ with genetic risk. American Journal of Psychiatry, 172(3), 259-265.
To clarify the relationship between IQ and subsequent risk for schizophrenia.
IQ was assessed at ages 18-20 in 1,204,983 Swedish males born 1951-1975. Schizophrenia was assessed by hospital diagnosis through 2010.
IQ had a monotonic relationship with schizophrenia risk across the IQ range with a mean change of 3.8% in risk per IQ point. This association, stronger in the lower versus higher IQ range, was similar if onsets within five years of testing were censored. No increased risk for schizophrenia was seen in those with highest intelligence. Co-relative control analyses showed a similar IQ-schizophrenia association in the general population and in cousin, half-sibling and full-sibling pairs. A robust interaction was seen between genetic liability to schizophrenia and IQ in predicting schizophrenia risk. Genetic susceptibility for schizophrenia had a much stronger impact on risk of illness for those with low versus high intelligence. The IQ-genetic liability interaction arose largely from IQ differences between close relatives.
IQ assessed in late adolescence is a robust risk factor for subsequent onset of schizophrenia. This association is not the result of a declining IQ associated with insidious onset. In this large, representative sample, we found no evidence for a link between genius and schizophrenia. Co-relative control analyses show that the association between lower IQ and schizophrenia is not the result of shared familial risk factors and may be causal. The strongest effect was seen with IQ differences within families. High intelligence substantially attenuates the impact of genetic liability on the risk for schizophrenia.
Graphically it looks like this:
Smarter people are less likely to get schizophrenia, and the function shows diminishing returns on the % scale, as it must (otherwise the predicted values would become negative at high IQs). And the important part is that high intelligence appears to be protective against schizophrenia:
The idea here is that everybody has some genetic risk level of schizophrenia, which one can index by weighing people's relatives. However, taking this risk factor into account, the risk of schizophrenia also depends on the interaction with intelligence of the person itself. In other words, if you have schizophrenic relatives and thus have a substantial chance of schizophrenia, yourself being smart can offset this risk more than would be expected simply by your intelligence alone in the general population. It might have been nicer to study a wider set of disorders, but this is what we have to go on.
So my thesis here is that the higher intelligence of Ashkenazis offsets some of the negative effects of their higher P factor scores, thus avoiding full-blown mental illness and instead gaining a chance of becoming a great contributor, AKA. a genius. From a purely hypothetical perspective, it also suggest that it would be possible to raise the rate of geniuses while raising average intelligence, by later on selecting for the P factor instead of against it. In fact, due to the negative genetic correlation between P factor and intelligence, selecting only for increased intelligence would tend to remove geniuses from our stock. That might be a terrible blunder for humanity. This illustrates some of the collective action problems with individualized eugenics via genetic editing and embryo selection. For more on that stuff, read Jonathan Anomaly's 2020 book Creating Future People.
If you would like to read more on Ashkenazi intelligence try these articles:
2019: Crémieux' The Jewish Advantage, a tour de force
2019: FAQ for Dunkel et al 2019 Ashkenazim polygenic score for intelligence, about our paper showing Jews have higher polygenic scores for education/intelligence