In defense of behavior genetics

Stuart Ritchie, the author of Intelligence: All That Matters and Science Fictions: How Fraud, Bias, Negligence, and Hype Undermine the Search for Truth, has written a trenchant critique of The New York Review of Books critique of The Genetic Lottery: Why DNA Matters for Social Equality at his Substack. Titled, Scientific Nihilism: A review of a review of Kathryn Paige Harden’s “The Genetic Lottery”, Ritchie goes into a lot of detail on why he disagrees with the critique. In the old blogosphere, we would call this a “fisking.”

Probably the most immediate issue I had with the review, and critiques of the science in The Genetic Lottery, is that the skepticism of the robustness of the inferences from the methods used in behavior genetics is so often lacking when it comes to the rest of the social sciences, in particular those areas that are normatively aligned with the views of the critics. For example, in the 1970’s some of the harshest critics of behavior genetics and later sociobiology were Marxists. Marxism of course purports to be scientific and based on a particular model of the universe. But the harsh skepticism that these Marxist scientists applied to the behavioral sciences that might utilize genetics they seem to have no use for in their own personal commitments.

Interestingly, Ritchie highlights something I missed, a Q & A with the co-authors of the review, where the historian of science Jessica Riskin says the following:

JR: I’m writing a book about the history of evolutionary theory focusing on the life and career of the French naturalist Jean-Baptiste Lamarck, in which I’ll follow the fortunes of Lamarck’s science from his lifetime up to the present. His ideas were foundational to modern biology—in fact, he coined the term “biology” in 1802, defining the science of life as a discrete field, and he also proposed the first theory of species change, or what we now call evolution. The emblem of Lamarckism became the giraffe, who, in stretching to reach high branches, lengthened its neck and forelegs by tiny amounts; these incremental changes, Lamarck proposed, added together over many generations, produced the giraffe’s distinctive form. Lamarck’s theory languished in exile for over a century, from roughly the 1880s until the 1990s, when the possibility that organisms might transform themselves heritably began re-entering mainstream biology in areas such as epigenetics.

Inter-generational heritability of epigenetic marks is a controversial area. It isn’t pseudo-science, but its validity seems to be tenuous in most cases, and most people who work in epigenetics don’t accept that it occurs in humans despite a paper or two that suggests that it does (I know this because I ask them this in private to get their candid view). The conflation of epigenetics as a pretty standard part of molecular genetic processes with what is basically neo-Lamcarkianism has made it so that many epigeneticists don’t even want to define themselves as such. Riskin’s allusion to the inter-generational heritability of epigenetic forces is certainly eyebrow-raising and makes me wonder at the variation in her epistemological standards…

Finally, Stuart Ritchie is a friend. You should support his Substack with your money if you can afford it. He believes the truth is important.

The twilight of American behavior genetics

Many people, including some prominent scientists, have emailed me about the review of K. Paige Harden’s book The Genetic Lottery in The New York Review of BooksWhy Biology Is Not Destiny – In The Genetic Lottery, Kathryn Harden disguises her radically subjective view of biological essentialism as an objective fact. It’s a pretty intense review. I thought it was mostly unfair, but even I winced at the punches that it got in. Give the devil his due?

There are two authors, M.W. Feldman and Jessica Riskin. I don’t know Riskin, but Feldman is an extremely eminent population geneticist whose influence is felt in others fields. He was an early founder of the field of cultural evolution, writing Cultural Transmission and Evolution with L. L. Cavalli-Sforza. From what I know, Peter Richerson attended classes on the topic taught by Feldman in the 1980s, and Richerson was Robert Boyd’s advisor, who was Joe Henrich’s advisor.

Indirectly Feldman is arguably the father of much of contemporary cultural evolution and cliodynamics.

As for what’s unfair in the piece, I think the below passage illustrates the method well:

“This polygenic index will be normally distributed,” Harden continues, now disguising an assumption—that there are intrinsic cognitive and personality traits whose distribution in a population follows a bell-shaped curve, a founding axiom of eugenics—as an objective fact.

Eugenics aimed to be an applied branch of hereditary science, and before the emergence of Mendelism, it was driven by ‘biometric’ thinking about continuous quantitative traits (though Francis Galton himself believed in “sports” and other noncontinuous changes). So the connection between eugenics and the normal distribution does exist…but the fact is that the normal (Gaussian) distribution is ubiquitous in science, and emerges out of the central limit theorem. Anyone with a cursory background in quantitative sciences won’t really associate the normal distribution with eugenics. How exactly was Harden going to write a book on behavior genetics without mentioning the normal distribution?

There is a lot of that sort of guilt-by-association and verbal sleight of hand. I think most fair-minded scientists will see what they did, but that’s not how the typical reader of The New York Review of Books will read the piece. Rather, they’ll see one hard-hitting salvo after another from two Stanford academics, one of whom is one of the most accomplished population geneticists of our day. How are they going to know about the ubiquity of the normal distribution and its centrality to much of modern statistics? Instead, most readers will experience an incredibly erudite and magnificent demolition of The Genetic Lottery and its presuppositions and implications.

Just to show you what I mean, let’s look at this passage. I’m going to add numbers that will help in the exegesis:

Harden condemns Jensen’s racism and rejects his assertion that social interventions are futile, but she doesn’t question his basic claim that genetic differences produce an [1] innate hierarchy of scholastic achievement. She also doesn’t acknowledge his dependence on fraudulent data from a 1966 paper by the English psychologist and geneticist Cyril Burt purporting to compare identical twins raised together and apart [2]. And nowhere does she cite the Princeton psychologist Leon Kamin’s 1974 devastating debunking of Jensen and Burt or engage with the critical problems Kamin raised there regarding twin studies in general, because of the impossibility of isolating genetic factors from environmental ones [3].

First, [1], there’s nowhere in the book that I recall Harden talking about “innate hierarchy.” One can see why Feldman and Riskin use this term, but the concept is repeated so often in the review that I believe most readers will believe this is exactly what Harden talked about in the book. No, it’s their interpretation and imputation. But repeated enough the allusive imputation becomes the literal fact.

As for [2], the Cyril Burt controversy continues down to the last I checked. He may have committed fraud, or he may not have. Feldman and Riskin take it as a given that the initial accusations of fraud were correct and not disputed. The reader won’t know the controversy about the controversy. As for [3], the reader will be unaware that in the 1970’s Kamin actually floated the position that the heritability of intelligence was ~0, severely undermining his credibility as a sagacious researcher. Second, the implication that there is an impossibility of isolating genetic factors from environmental ones is coherent in light of all the complexities of…complex traits. But this applies to many behavioral and nonbehavioral traits that are polygenic. Should we entertain the possibility that we can’t adduce the genetic aspect of schizophrenia due to philosophical quibbles about causality? (it’s very heritable)

If you want to know more about behavior genetics and genomics, I recommend this interview I did with James Lee, or this one from the fall with Alexander Young. As for Harden and The Genetic Lottery, I’m glum about the prospects for any project like this in this country. Though Harden is a tenured academic and comes out of a pretty good lineage (her advisor is Eric Turkheimer), ever since the bizarre piece in The New Yorker her reputation in many biological academic circles has taken a hit. From everything I know, she is sincere, earnest and a legitimate political progressive/liberal. But you wouldn’t know that from what some people say, and the lie repeated often enough becomes the truth. In 2006 I interviewed the famed population geneticist James F. Crow, and he stated that he felt “strongly that we should not discourage a line of research because someone might not like a possible outcome.” Crow died in 2012 at the age of 96, and from what I can see this sort of stance is mostly held by older academics.

A different wind blows in the future. Harden has tenure, and a band of her fellow travelers will continue to exist in American academia, but more and more they will be pariahs. Why? I’m not progressive so that’s beyond my pay grade. But there are other countries out there, so there will be places this sort of research continues.

The truth is what it is. No matter what the flock says.

Addendum: Bert Hölldobler, a long-time collaborator of E. O. Wilson has written a defense of him. Richard Lewontin was a great population geneticist, but I think his biggest impact will turn out to be the style of intellectual pugilism he promoted. It’s normative now among many younger academics. Here’s a section that jumped out at me:

It was a point that Dick Lewontin himself acknowledged when he showed up at my office the next day, apparently eager to soften what he had said. Although I respected Lewontin as a scientist and colleague at Harvard, I did not appreciate his ideologically driven “sand box Marxism.” When I asked why he so blithely distorted some of Ed’s writings he responded: “Bert, you do not understand, it is a political battle in the United States. All means are justified to win this battle.”…

Genetic correlation between friends

There is an interesting, and sexy, line of research which suggests that people who are non-related friends are genetically more similar than you’d expect. For years people have been telling me privately that this is not likely to be robust, and probably just really really subtle structure (friends of mine). But most of these were private gripes. Now a group has written a preprint outlining the basis from skepticism, No evidence for social genetic effects or genetic similarity among friends beyond that due to population stratification: a reappraisal of Domingue et al (2018):

Using data from 5,500 adolescents from the National Longitudinal Study of Adolescent to Adult Health, Domingue et al. (2018) claimed to show that friends are genetically more similar to one another than randomly selected peers, beyond the confounding effects of population stratification by ancestry. The authors also claimed to show ‘social-genetic’ effects, whereby individuals’ educational attainment (EA) is influenced by their friends’ genes. Neither claim is justified by the data. Mathematically we show that 1) although similarity at causal variants is expected under assortment, the genome-wide relationship between friends (and similarly between mates) is extremely small (an effect that could be explained by subtle population stratification) and 2) significant association between individuals’ EA and their friends’ polygenic score for EA is expected under homophily with no socio-genetic effects.

Almost no one is a genetic determinist except in your Communist imagination

Next summer I’m going to be giving a talk at the ISIR meeting. I’m a little bemused about this since, to be honest, I don’t talk much about behavior genetics and intelligence anymore.

Until August of 1998, I had rather conventional views for someone of my education and social background on psychometrics. Then I read Chris Chabris’ article in Commentary. From that, I began to conclude the “orthodoxy” that was presented in the elite media really wasn’t representative of what was going on in the field of psychometrics. It’s kind of like thinking that you get a balanced view of the Arab-Israeli conflict from reading Commentary.

Over the next few years, I read some books, review papers, and updated my views. Every few years I read a book or checked out a paper to see if anything had changed…and usually not to my eye as someone who is not in the field. About a decade ago I read What Is Intelligence?: Beyond the Flynn Effect. More recently I read Stuart Ritchie’s Intelligence and Richard Haier’s The Neuroscience of Intelligence. And other things here and there.

I’ll be reviewing Blueprint: How DNA Makes Us Who We Are, but I do wonder if it’s nothing more than an incremental improvement upon The Nurture Assumption: Why Children Turn Out the Way They Do.

Incrementalism isn’t a problem. I am a big fan of genomics. But its impact has been variable. And frankly in some fields less than you might think. I don’t believe it has changed our understanding of evolutionary process qualitatively (rather, it has allowed a finer-grained resolution to certain arguments around particular hypotheses). Educational attainment 3 is great. But does it change how heritable I think intelligence is in a qualitative sense? Not really. We already knew it was a heritable trait, and we’ve known it for a long time.

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Drawing on the slate of human nature

Some of you have been reading me since 2002. Therefore, you’ve seen a lot of changes in my interests (and to a lesser extent, my life…no more cat pictures because my cats died). Whereas today I incessantly flog Who We Are and How We Got Here: Ancient DNA and the New Science of the Human Past, in 2002 I would talk about Steven Pinker’s The Blank Slate: The Modern Denial of Human Nature quite a bit. The reason I don’t talk much about The Blank Slate is that some point in the 2000s I realized my future deep interests were going to be in population genetics, rather than behavior genetics and cognitive psychology. If you are not a specialist who doesn’t follow the literature. Who doesn’t “read the supplements”. You’re going to stop gaining anything more from books at a certain point.

Similarly, after I read In Gods We Trust: The Evolutionary Landscape of Religion, I read a lot of books on the cognitive anthropology of religion. Until I didn’t. Now that Harvey Whitehouse has teamed up with Peter Turchin, I suspect I’ll check in on this literature again.

But life comes at you fast. Today I think the broad thesis of The Blank Slate seems so correct, that we are not a “blank slate”, that no one would argue with that. Rather, the implications of that thesis are highly “problematic,” and social and cultural constructionism has really gone much further on the Left operationally than they were in the early 2000s. To give a concrete example, you can admit that sex differences are real and significant, but you have to be very careful in mentioning or highlighting specific instances or cases where they matter.

Moving to a more controversial topic, for a long while I’ve pretty much ignored the genomic study of the normal variation of cognition. The reason is that until recently all the studies were very underpowered to detect much of anything. The sample sizes were too small in relation to the genetic architecture of the trait because of the “Fourth Law of Behavior Genetics.”

As 2018 proceeds I think we can say that we are now in new territory. On Twitter, Steve Hsu seems positively ecstatic over a paper that just came out in PNAS. His blog post, Game Over: Genomic Prediction of Social Mobility summarizes it pretty well, but you should read the open access paper.

Genetic analysis of social-class mobility in five longitudinal studies:

Genome-wide association study (GWAS) discoveries about educational attainment have raised questions about the meaning of the genetics of success. These discoveries could offer clues about biological mechanisms or, because children inherit genetics and social class from parents, education-linked genetics could be spurious correlates of socially transmitted advantages. To distinguish between these hypotheses, we studied social mobility in five cohorts from three countries. We found that people with more education-linked genetics were more successful compared with parents and siblings. We also found mothers’ education-linked genetics predicted their children’s attainment over and above the children’s own genetics, indicating an environmentally mediated genetic effect. Findings reject pure social-transmission explanations of education GWAS discoveries. Instead, genetics influences attainment directly through social mobility and indirectly through family environments.

Why does this matter? I’m assuming most of you have seen charts like the ones below, which “prove” how the game is rigged against the poor:

The problem that most behavior geneticists immediately have with these popular analyses, which now suffuse our public culture (e.g., the “representation” argument in academic science often takes as a cartoonish model that all groups will have equal representation in all fields given no discrimination; substantively almost everyone believes this isn’t true in some way, but for the sake of argumentation this is a bullet-proof line of attack which every white male academic is going to retreat away from), is that they ignore genetic confounds. This paper is an attempt to address that. Measure it. Quantify it. Characterize it.

The two most interesting results for me have to do with siblings and mothers. Unsurprisingly siblings who have a higher predicted educational attainment score genetically tend to have higher educational attainments. As you know, siblings vary in relatedness. They vary in the segregation of alleles from their parents. Some siblings are tall. Some are short. This is due to variation in genetics across the pedigree. People within a family are related to each other, but unless you are talking Targaryens they aren’t exactly alike. Similarly, some siblings are smart and some are not so smart, because they’re “born that way.”

We knew that. Soon we’ll understand that genomically I suspect.

Second, we see again the importance of maternal effects and non-transmitted alleles. Mothers who have a higher predicted level of education have children with more education even if those children don’t inherit those alleles.* One natural conclusion here is mothers with a particular disposition shaped by genes are creating particular environments for their children, and those environments let them flourish even if they do not have their mother’s genetic endowments. This actually has “news you can use” implications in life choices people make in relation to their partners.

The study ends on a cautionary note. Residual population substructure can cause issues, correcting which can attenuate or eliminate such subtle and small signals. The sample sizes could always get bigger. And ethnically diverse panels have to come into the picture at some point.

But Razib abides. This study had a combined sample size of >20,000 individuals. Then you have the other recent paper with 270,000 individuals, Genome-wide association meta-analysis in 269,867 individuals identifies new genetic and functional links to intelligence. All well and good, but I wait for greater things. There is no shame in waiting for better things. And I prophesy that a greater sample size shall come to pass before this year turns into the new.

And you know what’s better than 1 million samples? How about 1 billion samples!

* Note that the models are controlling for a lot of background socioeconomic variables.

Your impatience is in your genes! (well, some of it)

Nature Neuroscience has a short communication which is very intriguging, Genome-wide association study of delay discounting in 23,217 adult research participants of European ancestry. How’d they get such a large sample size? Collaborating with our friends at 23andMe.

That being said, the abstract leaves a little to be desired:

Delay discounting (DD), the tendency to discount the value of delayed versus current rewards, is elevated in a constellation of diseases and behavioral conditions. We performed a genome-wide association study of DD using 23,127 research participants of European ancestry. The most significantly associated single-nucleotide polymorphism was rs6528024 (P = 2.40 × 10−8), which is located in an intron of the gene GPM6B. We also showed that 12% of the variance in DD was accounted for by genotype and that the genetic signature of DD overlapped with attention-deficit/hyperactivity disorder, schizophrenia, major depression, smoking, personality, cognition and body weight.

First, “Delay discounting (DD)”, is another way to say that you have high time preference. That is, you won’t forgo some gains in the short term for greater gains in the long term. You would really “fail” the marshmallow test.

Though there have been legitimate criticisms of the replicability of the effect size of the marshmallow test, there almost certainly is something to time preference and delayed gratification, and its relationship to the ability of young children to master the marshmallow test. In a macroeconomic sense societies characterized by low time preference can sustain lower interest rates, and lower interest rates have all sorts of stimulative properties on long-term economic growth.

But to be clear, the paper above does not detect a variant SNP, rs6528024, which explains 12% of the variance in DD. Rather, 12% of the variance could be accounted for by SNP-chip variance. That is, one could explain the “missing heritability” using the markers they had. The total heritablity of the trait is quite higher, 46% to 62% proportions are citied in the paper (narrow-sense). This means that of the total variance of the trait about half could be explained by additive genetic variance. Obviously the SNP-chip only captured a small minority of that additive genetic variance.

DD is correlated with a lot of things. There is a positive phenotypic correlation with:

  • Smoking
  • Substance abuse
  • Obesity
  • ADHD

They observed a positive genetic correlation between the variants associated with DD and:

  • Smoking
  • Neuroticism
  • Depression

And a negative genetic correlation with:

  • College completion
  • Years of education
  • Childhood IQ
  • Schizophrenia

In relation to the last, schizophrenia and DD are positively correlated phenotypically. That probably means that the underlying genetic causes of schizophrenia and DD are very different.

The patterns of correlations offer up a lot of avenues to speculate. They do a little of it in the paper, but are appropriately cautious. It seems entirely likely that in the near future we’ll be able to characterize a lot of the heriability genomically. When we figure out time preference and intelligence we’ll have come close to answering many of the questions that explain why different people have different life outcomes.

Note: It is no surprise that there is a negative correlation between DD (high time preference) and conscientiousness. Also, the association they found, GPM6B, has pretty clear biological relevance. It’s almost certainly real.

Liberals will never disappear (neither will atheists)

In Quillette Hrishikesh Joshi and Jonny Anomaly* ask Are Liberals Dying Out? Since the piece has been shared a fair amount (judging by my Twitter timeline), I thought I should respond to why I don’t think that is a major concern. Let me jump to their last paragraph:

Nevertheless, despite cultural trends, the best available evidence suggests that political ideology is heritable, and that people with liberal personality traits currently have far fewer children than conservatives. If this trend continues, it is possible that the reproductive choices people are making today will influence the political climate of future generations. Over the long run, conservatives could end up winning the ideological contest with fertility rather than arguments.

First, I don’t think the title reflects the modest contentions of the piece. I beseech the editors of Quillette to not engage in the titular hyperbole so common in the mainstream media!

I agree that political orientation seems heritable. That is clear in books like Born That Way. But heritability expresses itself in an environmental context. If you had a totalitarian government most of the phenotypic variation would disappear. Yes, there would be dissidents, but they’d be freaks. Most humans would conform (no, I don’t think the citizens of Soviet Russia were genetic freaks unable to grasp freedom like Howard Roark). The correlation between religiosity and fertility varies by society as well. The more secular the society, the bigger the gap (though last I checked this was not true in China). In a totally conservative future heritable variation for liberalism could just reemerge.

Second, political orientation exists on a relative plane. If one imagines it as some specific thing, or disposition, one can imagine that in the future the liberal-conservative spectrum would exist, but just be shifted. Quantitative genetics has shown that selection can move the mean many standard deviations. I don’t think this is a strong objection to their overall point, but it gets at the fact that we view liberal-conservative tendencies along a distribution (1980s liberal commentator Jeff Greenfield was widely known for making disparaging comments about gays i the prime of his career; that did not destroy his career as a liberal pundit at that time). Perhaps liberal have already won in an age when most conservatives understand and accept that gay marriage is here to stay.

Third, some of the variation is not heritable. It’s random. In fact around half of it within the population. Some people may just be liberal for stochastic reasons. You aren’t going to get rid of this with selection.

Perhaps most essential in terms of theory: frequency dependence. The dynamics of human interaction and decision making are such that the frequency of liberals declining might have an impact on their fitness. To give a weird example, perhaps an economically post-Malthusian society needs a certain number of sub-replacement liberals who engage in particularly productive work to maintain itself. If society slouched rapidly back toward Malthusianism perhaps everyone would just trudge along at replacement.

The big picture problem is assuming constant directional selection and exhaustion of heritable variation is all well and good when you are selecting for wax-seed oil, but human societies are non-linear systems which are subject to big shocks. They aren’t controlled agricultural genetic experiments.

Finally, let me use an analogous case to make an empirical objection. Many people tell me that the future will be religious due to the same dynamics above. This despite the century long trend toward secularization (parenthetical, God is Back was an ill-timed books, as the United States was shifting toward secularization at that time).

But I want to go back further. France was the first nation to start the demographic transition. In the early 19th century the secular elite was worried about the fertility of devout Roman Catholics, in particular the Poles who were arriving. The secular future they envisioned was threatened. It’s been nearly 200 years since these worries, and in those 200 years France has become more and more secular.

My point with this illustration is that if your theory can not predict the past, it can’t predict the future. At least not robustly. Liberal people will always be with us. So will shy people. And atheists too. They may wax and wane, but human variation persists. On the evolutionary genetic level I think frequency dependent dynamics are such that the fait, in the medium term, of low fitness traits is generally to become oddballs, not extinct. And once they are odd they may become fortunes favorites….

* For real, is that his real name?

Just because it’s not hereditary does not mean you can affect it

A comment below from Andrew:

Love to see a post about which human traits worth caring about are notable for having little or no hereditary component. It is all good and well to know what we cannot change, but it makes more sense to focus personally and as a parent on those things that aren’t genetically preordained.

This is a common sentiment I’ve seen. If you haven’t read The Nurture Assumption, please do so. I’d say a substantial reason I think that The Blank Slate is a good book is that Steven Pinker promoted Judith Rich Harris’ work.

With that out of the way: the implication in the comment above is that hereditary traits are the ones you have least control over, so you should focus on the non-hereditary traits. To some extent there is truth in this. Micronutrients are important. You don’t want to turn you children into cretins.

But a major problem with the idea that we can impact environmental impacts on characteristics is that on many traits we don’t know what those environmental impacts are. You can take a behavior genetic model and come to the following conclusion: within the population 50% of the variation is due to genes, 40% of the variation is due to non-shared environment, and 10% of the variation is due to shared environment (parents). We don’t really usually know what the non-shared environment means. It might be just developmental noise. It might be epistatic genetic effects. Or, in relation to behavior, it might be peer group, as Judith Rich Harris asserts.

We just don’t know. What that means is that the hereditary components are what you have legitimate effective control over through mate choice. And shared environment. These two combined are not nothing. And of course there is the impact of nation or community on the environmental in which propensities are expressed.

Addendum: The non-shared environmental variance was once explained to me as a “noise” factor. Just to give you a sense of how well we understand it.