Nature v. Nurture Updated

In Human Diversity, Charles Murray presents the latest research (as of January 2020) in biology and sociology to bring Nature versus Nurture up to date. The overarching strength of this work is Murray’s conscientiousness. His narrative encourages skeptical readers of all stripes to put their guard down, presenting scientific findings burdened with caveats but free from orthodoxy (academic, political, and religious). As a social scientist, Murray take sides in some debates, but he also supplies dissenting voices to avoid impressions of false consensus. So much decisive data and enabling education is found in Human Diversity that it becomes a pre-requisite for informed social policy discussions.

Human Diversity provides its best insight when it confronts the Nurture theory of male-female differences, which suggests that variations “should be smaller for more egalitarian or developed societies.” Murray orchestrates seven studies conducted between 2005 and 2018 to examine this notion relative to personality, academic skills, spatial skills, and vocational choices. In contrast to the Nurture theory, countries with more equality exhibit larger sex differences in all five of these areas! Human Diversity introduces several hypotheses for why and how freedom and gendered outcomes might coincide.

Human Diversity also includes the best primers that I’ve ever found on statistics, genomics, neuroscience, non-binary genders, evolution, and sociological measurements. One of the latter is “Twin Studies,” which Murray expounds and defends to allow a broader scientific discussion of “this great debate.” However, besides Nature (biology and genetics) and Nurture (“common” family influences, socioeconomic status, and culture), Twin Studies also yield a third factor I call ‘Neither’ (choice, chance, “differential” influences, and... everything else).

When it comes to wealth or class, Murray renounces fate with glee: the aggregate factor of Neither explains “the bulk of the variance in [material] success in life.” Still, Murray’s review concludes that intelligence is the only solo factor with sizeable correlation to class. When considering aggregate factors, Murray maintains that intelligence is the dominant explanation for wealth during adulthood. For those who are skeptical of this analysis, Human Diversity is profuse in its discussion of theories and research about measuring intelligence as well as overlaps between socioeconomic status, “Big Five” personality traits, and intelligence.

Human Diversity’s discussion of “ancestral populations” (the scientific term for “race”) offers many updates due to recent advancements in genomics. Along with a short history of migration theories, and a note on commercial DNA tests, Murray focuses on a 2008 paper that finds seven ancestries corresponding to the seven continents (see Figure 1A of the source). Murray then reviews current evidence of genetic variation between these populations and forecasts that many more variations will soon be found. The section ends with counsel to greet each new variance with a “that’s interesting” attitude instead of prejudice or denial.

Within its rehearsal of male-female differences as “consistent,” “worldwide,” and “meaningful,” Human Diversity discusses several competing interpretations of the data. Murray draws a picture of what mathematical correlation denotes, reviews guidelines on when a variation is “big enough to be interesting,” and reviews competing proposals for aggregating differences. As with race, sex differences need not lead to prejudice or denial. Instead, Murray endorses a metaphor of “differences in cognitive toolboxes” whereby men and women can successfully use their respective strengths to solve the life’s problems.