Evolved Brains in Evolved Bodies

In his Pulitzer Prize-winning book Guns, Germs, and Steel, Jared Diamond seeks to explain the ultimate causes of modern societies’ clear disparities in wealth and power. “It is perfectly obvious to everyone,” Diamond points out, “that different peoples have fared differently in history.” But why? One popular explanation for “all those glaring, persistent differences in peoples’ status,” he suggests, “involves implicitly or explicitly assuming biological differences among peoples.” Yet such assumptions, he argues, are not merely wrong but racist.

Diamond accepts that for many people it could still “seem logical to suppose that history’s pattern reflects innate differences among the people themselves”:

We’re told that [inter-group inequality] is to be attributed not to any biological shortcomings but to social disadvantages and limited opportunities. Nevertheless, we have to wonder. … We’re assured that the seemingly transparent biological explanation for the world’s inequalities … is wrong, but we’re not told what the correct explanation is.

Unless there is “some convincing, detailed, agreed-upon explanation for the broad pattern of history,” Diamond suggests, “most people will continue to suspect the racist biological explanation is correct after all.” His guns, germs, and steel thesis is an attempt to provide just such a detailed and convincing counterargument to these widespread yet supposedly racist beliefs about the causes of present-day global disparities. 

In the quarter century since Guns, Germs and Steel was published, Diamond’s deservedly lauded “science of human history” theories have become increasingly influential, inspiring anthropologist Joseph Henrich, author of The WEIRDest People in the World and public intellectual Yuval Noah Harari, among others. And while Diamond’s thesis has also received its share of criticism, one central tenet of the book—the dismissal of biological explanations of social inequalities as racist—has become more entrenched than ever.

Yet the past 25 years have also witnessed an explosion in our understanding of human genetics and genomics. Recent insights into our own species’ evolved biology fatally undermine this key aspect of Diamond’s argument: his rejection of the possibility of meaningful “biological differences among peoples.” Despite growing genetic evidence, however, the very idea of significant genetic variation between human populations is still routinely rejected. This attitude is, however, only likely to perpetuate the “glaring, persistent differences” that concerned Diamond and trouble so many other well-meaning egalitarians.

To grasp why, we can start by examining an unintended inconsistency in Diamond’s own reasoning.