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Charles Murray’s *Human Diversity*

His new book is coming out in January, and the subtitle is The Biology of Gender, Race, and Class. I will get to the details shortly, but my bottom-line review is “Not as controversial as you might think,” but do note the normalization at the end of that phrase.

Here is one bit from p.294 toward the end of the book:

Nothing we are going to learn will diminish our common humanity.  Nothing we learn will justify rank-ordering human groups from superior to inferior — the bundles of qualities that make us human are far too complicated for that.  Nothing we learn will lend itself to genetic determinism.  We live our lives with an abundance of unpredictability, both genetic and environmental.

Most of the book defends ten key propositions, laid out on pp.7-8.  The first four of those propositions concern differences between men and women (“Sex differences in personality are consistent worldwide…”) and I do not find those controversial, so I will not cover them.  The chapters on those propositions provide a good survey of the evidence, and a good answer to the denialists, though I doubt if Murray is the right person to win them over.  Let’s now turn to the other propositions, with my commentary along the way:

5. Human populations are genetically distinctive in ways that correspond to self-identified race and ethnicity.

True, but Murray’s analysis did not push me beyond the usual citations of lactose intolerance, sickle cell anemia, adaptation to high altitudes, and the like.  That said, pp.190-195 offer a very dense discussion of target alleles for various traits, such as schizophrenia, and how those target alleles vary across different groups.  I found those pages difficult to follow, and also wished that discussion had been fifty pages rather than five.  Toward the end of that discussion, Murray does write (p.194): “…proof of the role of natural selection for many genetic differences will remain unobservable without methodological breakthroughs.”  With that I definitely agree.

On p.195 he adds “It is implausible to expect that none of the imbalances will yield evidence of significant genetic differences related to phenotypic differences across continental populations.”  That returns to my core point about this book not shifting my priors.  You could agree with that sentence (noting the ambiguity in the word “significant”) and still have a quite modest vision of what those differences might mean.  In any case, nothing in the book pushes me beyond that sentence in the direction of the geneticists.

And here the contrast with the chapters on men and women becomes (unintentionally?) glaring: those biological differences are relatively easy to demonstrate, so perhaps hard-to-demonstrate biological differences are not so significant.  That too is just a conjecture, but there are multiple ways to play the “absence of evidence” and “how to interpret the residuals” cards, and I wish those had received a more extensive philosophy of science-like discussion.

Now let’s move to the next proposition:

6. Evolutionary selection pressure since humans left Africa has been extensive and mostly local.

That one strikes me as a miswording or misstatement, though I do not see that it corresponds to any actual mistakes in the broader text.  You might think that general, non-local evolutionary selection for all humans has been quite large over the millennia, relative to local selection.  I genuinely do not know the ratio here, but Murray does not seem to address the actual comparison of “across all human groups” vs. “local” as loci of selection pressures.

Next up:

7. Continental population differences in variants associated with personality, abilities, and social behavior are common.

Clearly true, but note this proposition does not claim biological roots for those differences.  The real question comes in the next proposition:

8. The shared environment usually plays a minor role in explaining personalities, abilities, and social behavior.

Here I have what I think is a major disagreement with Murray.  If he means the term “shared environment” in the narrow sense used by say twin studies, he is probably correct.  But in the more literal, Webster-derived conception of “shared environment” I very much disagree.  Culture is a truly major shaper of our personalities, abilities, and social behavior, and self-evidently so. For my taste the book did not contain nearly enough discussion of culture and in fact there is virtually no discussion of the concept or its power, as a look at the index will verify.  The real lesson of “twins studies plus anthropology” is that you have to control almost all of a person’s environment to have a major impact, but a major impact indeed can be had.  I behave very differently than my Irish potato famine ancestors, and not because I am genetically 1/8 from the Madeira Islands.  That said, within the narrower range of environmental variation measured in twins studies…well those studies seem to be fairly accurate.

9. Class structure is importantly based on differences in abilities that have a substantial genetic component.

Correct as stated, but I see those differences as much less genetic than Murray does.  For instance, IQ is to some extent heritable, but how much does that shape economic outcomes?  It is worth turning to Murray’s discussion on p.232 and the associated footnote 17 (pp.428-429).  His main source is what is to me a flawed meta-study on IQ and job performance (Murray to his credit does also cite the best-known critique of such studies).  I would opt more directly for the labor market literature on IQ and individual earnings, based on actual measured wages, which shows fairly modest correlations between IQ and earnings (read here, here and here).  So, at the very least, the inherited IQ-based permanent stratification version of The Bell Curve argument is much more compelling to Murray than it is to me.

10. Outside interventions are inherently constrained in the effects they can have on personality, abilities, and social behavior.

Clearly this is literally true, if only because of the meaning of “constrained.”  But mostly I would repeat my remarks on culture from #8.  Cultures change, and over time they are likely to change a great deal.  For instance, early in the 20th century, Korea, Japan, and China often were described as low work ethic cultures.  As cultures change, in turn those cultures can shape the personalities, abilities, and social behaviors of subsequent generations, in significant ways albeit constrained.  So while Murray is correct as stated, I believe I would disagree with his intended substantive point about the weight of relative forces.

Overall this is a serious and well-written book that presents a great deal of scientific evidence very effectively.  Anyone reading it will learn a lot.  But it didn’t change my mind on much, least of all the most controversial questions in this area.  If anything, in the Bayesian sense it probably nudged me away from geneticist-based arguments, simply because it did not push me any further towards them.

Murray of course will write the book he wants to, but my personal wish list was two-fold: a) a book leaving most of the normal science behind, and focusing only on the uncertain and controversial frontier issues, in great detail, and b) much more discussion of the import of culture.

Most of all, I am happy that America’s culture of achievement is inducing Murray to continue to produce major works at the age of 76, soon to be 77.

You can pre-order here.

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