Human Diversity: The Biology of Gender, Race, and Class, by Charles Murray (Twelve, 528 pp., $35)

The dumb kids at Middlebury College had no idea what they were setting in motion when they stopped Charles Murray from speaking. At an instantly infamous 2017 lecture, students shouted down his speech, waited through a livestreamed discussion between him and a faculty member given from a private location, and swarmed him after the event, injuring the faculty member.

Murray, you see, had been thinking about swimming back toward the fraught waters he and the late Richard Herrnstein had explored in 1994’s The Bell Curve — notions that traits such as intelligence are hugely important in determining who gets ahead in modern societies, and that gaps on those traits among social groups, including racial groups, could be partly genetic in origin. His wife had been telling him not to.

“Confound it!” he recalls her saying after the Middlebury affair (“. . . or two syllables to that effect”). “If they’re going to do this kind of thing anyway, go ahead and write it.” And now, three years later, we have Human Diversity: The Biology of Gender, Race, and Class.

This isn’t an intemperate screed meant to trigger oversensitive 19-year-olds, however. Instead, it’s a patient and generally cautious explanation of where the science stands in the three highly contentious areas mentioned in the subtitle: the biological underpinnings of sex differences, social-class differences, and racial differences.

Those who’ve been following developments in these areas will find little that’s surprising. But those new to the topics will learn a lot, so long as they understand basic statistical concepts well enough to follow Murray’s often-a-bit-technical prose. {snip}

Murray begins with sex differences because they’re the most obvious and hard to deny. {snip}

{snip}

Lastly, there’s race — the topic that attracted nearly all of the controversy associated with The Bell Curve despite taking up only a minority of its pages. Interestingly, Murray is more circumspect now than he was in that tome a quarter century ago, when he and Herrnstein wrote that it was “highly likely” that part of the gap between blacks’ and whites’ IQ scores was genetic. Here he is more interested in debunking the notion that race is nothing more than a “social construct” that has nothing to do with genes at all.

Even on that front he’s pretty timid. Indeed, he begins by agreeing to dispense with the word “race” when talking about genetics, because the word carries so much baggage and the professional geneticists have mostly abandoned it. Instead he goes with “population,” while noting that the ancestral “populations” that geneticists distinguish from one another overlap heavily with commonly used racial categories.

Yes, these groups can be identified using nothing but DNA, and yes, there are some important genetic differences among populations: Some less controversial ones affect skin color, malaria resistance, and adaptations for living at high altitudes. In other words, humans have continued to evolve in lots of ways since they spread out across the globe, and different changes have taken hold in different environments. But what about hot-button psychological characteristics such as intelligence?

You’d think we’d be getting close to answering that question by now. Recall that we’ve actually identified a lot of genes that affect these traits, and even developed scoring systems that roughly predict from someone’s DNA how he’ll turn out. One imagines you could just apply these techniques to the average DNA profile of each racial group — excuse me, population — and get a simple answer, albeit a tentative one that would become more precise as methods improved and additional influential genes were discovered.

But it’s not that easy. For a variety of technical reasons, you can’t apply a single scoring system across multiple populations, at least with current methods. Murray notes that the genetic variants we’ve singled out as playing a role in assorted traits often show up more frequently in some populations than others — a point he makes more painstakingly than he probably needs to, with a series of scatterplots and tabulations — but he admits these gaps are only grist for future, more sophisticated research. His bottom line is not much different from the point made by the prominent Harvard geneticist David Reich in a 2018 New York Times piece: Human populations differ at the genetic level, and we have to prepare for the possibility that these genetic differences substantively affect traits we’d rather they didn’t, but we don’t know the specifics yet.

In 1994, Herrnstein and Murray lit the world on fire with a book that made highly controversial claims about IQ, class, and race. Human Diversity’s publicists no doubt hope for a repeat performance; I had to sign a nondisclosure agreement to see the text before the release date. But the result is actually, as Murray himself promises early on, pretty boring for those already familiar with the topics it covers. What it is, is an excellent primer for the uninitiated — at least for a few years, by which point new science will likely have superseded much of the research discussed here.

{snip}