It is time for another entry into the mailbag series where I answer feedback email from readers and others. If you want to send me a question, comment or any other kind of feedback, please do so using the contact form on the about page.
The commenter Foma left the following comment on an unrelated post that I thought might be useful to expand into a more detailed treatment covering the problems with race realism, how race realists misunderstand heritability and their obsessive fetishizing of scientist Richard Lewontin.
Hey Emil, what do you think of Gregory Cochran’s latest post about Lewontin? Is it factual or isn’t?
The post in question is Lewontin wins the Crafoord Prize written by race realist Gregory Cochran. What is race realism, who is Lewontin and are the claims by Cochran reasonable or not?
Race realists are individuals who believe that modern genetic research has vindicated racial divisions created in the 1700s. They often rationalize this belief by appealing to trivial misunderstandings of published research or outright pseudoscience. One of their main targets over the last couples of decades have been evolutionary biologist and geneticist Richard Lewontin. Why? It all goes back to experiments done in the late 1960s through late 1970s. Using gel electrophoresis, he was able to show that individual of the model organism called common fruit fly were more genetically diverse than previously thought, and thus ushered in a revolution in population genetics. For this and related research, he was rewarded with the 2015 Crafoord Prize in Biosciences.
Lewontin and human genetic variation
Later, he used a similar approach to argue that most of human variation occurred within populations and not between them and argued that the concept of race was not that useful or important when it comes to humans.
However, Lewontin’s argument was incomplete as his analysis was on the level of a single locus. Critics, such as A. W. F. Edwards, lamented that there could be correlations between different loci and that this could offer a justification for traditional racial categories. Modern studies, such as Li et al. (2008) and Rosenberg et al. (2002), that look at 300+ loci and 650 000 single-nucleotide polymorphisms show that the vast majority of human genetic variation (e. g. 93-95%) is to be found within human population and only a tiny fraction between them (e. g. 3-5%). So although the original argument by Lewontin had an important limitation, his conclusion is supported by modern genetic research.
To be sure, human population structure does exist, but human genetic diversity is considerably different from the erroneous views held by most race realists. With the exception of geographically isolated populations far from others, most of human genetic variation is clinal and often change more or less continuously with geography. It is easy to create the illusion of distinct genetic clusters by having a low sampling density: sample a few people from Sweden, some from Nigeria, some from Bolivia and some from China and plot the results and distinct genetic clusters appear. However, if you sample many populations living in between these groups, the emerging pattern does not lend itself to such a simplistic interpretation and do not support the existence of distinct genetic clusters (Serre and Pääbo, 2004).
When refuted, most proponents of pseudoscience often try to move the goalposts and change the subject. Race realists (or “human biodiversity activists”) often respond by claiming that there still are large phenotypic differences or that they think traditional racial categories are vindicated by genetic research no matter how small the between-group differences are. These approaches collapse because phenotype is caused by an interaction between genetics and environment and one cannot naively infer the relative importance of genes and environment on the level of individuals with such an approach. It is possible to measure a different, but related, metric called heritability. This tells us how much of the variation in phenotype can be explained by the variation in genes, but not how important the genetic contribution is on an individual level. The other goalpost move fails because it lacks a serious appreciation for biological significance. Just because a difference exists does not by itself mean that such a difference is large enough to be of biological relevance. There has to be an empirical argument that bridges that gap and race realists have so far been unable to present such an argument.
Lewontin and heritability of IQ
A similar problem face the race realist treatment of the heritability of IQ. It says nothing about how important genes are for intelligence, only how much of the variation in IQ can be attributed to the variation in genes. These are two completely different things, yet the wishful thinking of many race realists often seduce them into conflated the two. In reality, science is more complicated than that. High heritability do not mean that genes are especially important compared with environment and low heritability does not mean that genes are irrelevant. Heritability estimates are only valid for a particular population and a particular environment and says nothing about the cause of between-group differences. The article The Widespread Abuse of Heritability goes into additional details.
Lewontin and the critique of naive adaptationism
Reading the classic paper “The Spandrels of San Marco and the Panglossian Paradigm” by Gould and Lewontin (1979) almost 40 years later after decades of modern research on evolutionary biology and behavioral ecology is somewhat of a bizarre experience. Complaints about overreliance on natural selection as an explanatory factor, the ignorance of historical constraints, the lack of careful considerations of alternative hypotheses and the telling of just-so-stories about evolution may seem misbegotten in the mid 2010s, but was relevant criticisms in the late 1970s and it made researchers in related fields improve their experimental designs and theoretical understandings of evolution. Far from being “crap” as Cochran puts it, it played an important historical role in improving scientific research on evolutionary adaptations.
In sum, the post about Lewontin written by Cochran is more about ranting about Lewontin than any substantial intellectual contribution to the discussion.
References and further reading:
Gould, S. J., Lewontin, R. C. (1979). The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme. Proc. Roy. Soc. London B. 205. 581–598
Li, J. Z., Absher, D. M., Tang, H., Southwick, A. M., Casto, A. M., Ramachandran, S., . . . Myers, R. M. (2008). Worldwide Human Relationships Inferred from Genome-Wide Patterns of Variation. Science, 319(5866), 1100-1104.
Rosenberg, N. A., Pritchard, J. K., Weber, J. L., Cann, H. M., Kidd, K. K., Zhivotovsky, L. A., & Feldman, M. W. (2002). Genetic Structure of Human Populations. Science, 298(5602), 2381-2385.
Serre, D., & Pääbo, S. (2004). Evidence for Gradients of Human Genetic Diversity Within and Among Continents. Genome Research, 14(9), 1679-1685.