Inequality: A Genetic History, by genetics researcher Carles Lalueza-Fox, is the type of book that makes promises that it can’t keep.
Given the title, I was hoping for a discussion of how genes impact individual differences in wealth, income, and other markers of socioeconomic status. Abdel Abdellaoui and David Hill have done some fascinating work in this area (e.g., Abdellaoui et al., 2019; Hill, 2019). For example, these researchers–and others–have found that some genetic variants are more frequently found in wealthier people. Additionally, smarter people (with their own genetic variants) are more likely to migrate to cities–where there are more opportunities. This has profound implications for geographic inequality and may be one of the reasons why rural areas lag behind cities in many developmental indices.
Lalueza-Fox opens his book with a lot of hand wringing about economic inequality, with the standard citations to Piketty. He worries that “rampant inequality is no trivial matter” and that it has “moral considerations” (2022, p. 4). Lalueza-Fox never explains why economic inequality is a bad thing; he just thinks it is self-evident. One typical quote from Lalueza-Fox is:
. . . places like Mexico and Brazil are more inequal now than when military and political leader Simón Bolivar was alive. For those hoping to make the world a better place, it is a startling revelation.
Lalueza-Fox (2009, p. 2)
The reader doesn’t have to be a conservative or libertarian to see how myopic Lalueza-Fox’s focus on inequality is. By every metric, life in Mexico and Brazil is far better now than in the era of “El Libertador.” But because the Gini coefficient is higher than he likes, Lalueza-Fox thinks that the world is not a better place than it was 200 years ago. Of course, long-term stable inequality is not necessarily bad if a country’s economy is growing; as the supply-siders often say, a rising tide lifts all boats.
The next section of the book discusses the latest research on the creation and mixing of human populations in historic and prehistoric times. It is interesting, but those who have read David Reich’s (2018) book on the same topic will not learn anything new. Lalueza-Fox (2022) also discusses archeological evidence of inequality, such as an uneven distribution of grave goods in contemporary burials.
The longest section of the book focuses on evidence that reproductive success was not equal throughout human history. This is especially true across gender lines: females in the past are much more likely to have living genetic offspring than contemporary males. Among males, Lalueza-Fox (2022) makes a convincing argument that reproductive success was tied to economic, military, and/or social success. In other words, men at the top of the social hierarchy had more children. An extreme example of this is Genghis Khan, who may have been the paternal-line ancestor of a whopping 8% of men in the region (and 0.5% worldwide; Lalueza-Fox, 2022, p. 123). On the other hand, we will never know how many men and women at the bottom of the social hierarchy were denied reproductive opportunities and died as evolutionary losers.
What does all of this have to do with income inequality? Not much. After the initial chapter, Lalueza-Fox (2022) almost completely drops the topic and instead focuses on reproductive inequality. In the final chapter, Lalueza-Fox discusses “the future of inequality,” in which he worries about assortative mating and discusses how inequality is a danger to democracy (though how or why is never clear).
Given its putative topic, Lalueza-Fox’s (2022) book is most notable for what it doesn’t discuss. There is no mention of polygenic scores for socioeconomic status, genetic correlations between income and other variables (like intelligence and conscientiousness), the dysgenic effect of income in modern societies, the genetic transmission of social status (Clark, 2014, 2023), or many other relevant ideas. As a result, people who read Inequality: A Genetic History won’t learn much about inequality at all.
The book is short (just 141 pages, not counting references, the index, etc.), which is not long enough to develop a complex idea. In his acknowledgements, Lalueza-Fox states that he wrote “the main chapters of this book” (2002, p. 144) from mid-March to June of 2020 while on lockdown for COVID-19. This probably explains why the book feels half-baked and undeveloped: he basically stopped writing when lockdown ended. Consequently, Inequality: A Genetic History is an unfinished book that would have benefited from more gestation for it to live up to its title.
References
Abdellaoui, A., Hugh-Jones, D., Yengo, L., Kemper, K. E., Nivard, M. G., Veul, L., Holtz, Y., Zietsch, B. P., Frayling, T. M., Wray, N. R., Yang, J., Verweij, K. J. H., & Visscher, P. M. (2019). Genetic correlates of social stratification in Great Britain. Nature Human Behaviour, 3, 1332-1342. https://doi.org/10.1038/s41562-019-0757-5
Clark, G. (2014). The son also rises: Surnames and the history of social mobility. Princeton University Press.
Clark, G. (2023). The inheritance of social status: England, 1600 to 2022. Proceedings of the National Academy of Sciences, 120(27), Article e2300926120. https://doi.org/10.1073/pnas.2300926120
Hill, W. D., Davies, N. M., Ritchie, S. J., Skene, N. G., Bryois, J., Bell, S., Di Angelantonio, E., Roberts, D. J., Xueyi, S., Davies, G., Liewald, D. C. M., Porteous, D. J., Hayward, C., Butterworth, A. S., McIntosh, A. M., Gale, C. R., & Deary, I. J. (2019). Genome-wide analysis identifies molecular systems and 149 genetic loci associated with income. Nature Communications, 10, Article 5741. https://doi.org/10.1038/s41467-019-13585-5
Lalueza-Fox, C. (2022). Inequality: A genetic history. The MIT Press.
Reich, D. (2018). Who we are and how we got here: Ancient DNA and the new science of the human past. Pantheon Books.
