Does history matter?

We all like telling stories about our past, though often the distinction between true history and mythology is blurred. This may be harmless in some aspects of life, but not in science, which is supposed to be an attempt to understand things as they really are or were. But even science is susceptible to confusing mythology and history. An example is the way we describe human variation and its origins. Life is history, and the Darwinian revolution showed that it is a particular kind of history. Instead of being the results of a string of discrete creation events, the diverse species of the world are the result of continually acting processes that modify existing species, eventually generating new ones. As Darwin put it in his Origin of Species, divergence accumulating gradually over time leads first to ‘‘varieties’’ or subspecies, which, after further thousands of generations of divergence, become species. Darwin was entirely vague about how this phase transition between quantitative variation and qualitative differences actually occurs. Indeed, it is still an active area of research in evolutionary biology. The same issues apply closer to home, because a major objective in anthropology is to understand the origins of human variation. Since we’re so similar overall that we’re clearly a single species, a point repeatedly stressed by Darwin, the traditional anthropological approach to the ways in which we do differ is to typologically divide humankind into subspecies or races. However, identifying those categories has always been notoriously problematic. In Descent of Man, Darwin famously struggled with, then gave up on the attempt, declaring that ‘‘Every naturalist who has had the misfortune to undertake the description of a group of highly varying organisms, has encountered cases (I speak after experience) precisely like that of man; and if of a cautious disposition, he will end by uniting all the forms which graduate into each other, under a single species; for he will say to himself that he has no right to give names to objects which he cannot define.’’ Despite the well-known problems, anthropologists have persisted in dividing in order to conquer an understanding of human variation. Initially, these efforts rested on morphology. In the early twentieth century, the leading American anthropologist, E. A. Hooton suggested how to categorize human variation (Fig. 1). As he put it, ‘‘A race is a great division of mankind, the members of which, though individually varying, are characterized as a group by a certain combination of morphological and metrical features. . .which have been derived from their common descent.’’ Primary races are the product of ‘‘evolutionary factors,’’ while secondary or ‘‘composite’’ races have been produced by ‘‘long-continued intermixture of two or more primary races.’’ (Quotes from Ref. 2, p. 76). In what today sounds naively informal, Hooton suggested that we should first group individuals intuitively, using expert judgment to identify races, then apply multivariate statistical analysis to define races more precisely in terms of those traits that differ to statistically significant degrees. Hooton argued that this procedure will make the distinguishing features ‘‘very apparent.’’ ‘‘Pure’’ races will be identifiable; individuals that are admixtures of the pure races can then be characterized. Evolutionary change was due to genetic change, so in the dawning genetic age it seemed more modern to turn to genetics for the task of identifying different races. This thinking can be seen in the world’s leading human genetics text at that time. Racial types should be defined by traits that are clearly inherited, as could be shown, for example, by their Mendelian appearance in families. Such traits are inherent and permanent, not blurred by environment or life experience, and are faithfully transmitted from parent to offspring. Based on such traits, the authors of this text asserted that ‘‘In reality. . .the races are sharply delimited.’’ In fact, ‘‘Technically speaking, there is no such generalized being as ‘man’; there are only men and women belonging to particular races or particular racial crossings.’’ Yet a Mendelian trait, like eye color, varies among family members and over geographic space. Indeed the authors noted clearly that even within a racial group no two individuals are alike. This has always posed a curious problem for doing typology within an evolutionary context. How can a trait be useful in defining discretely differing races if it varies even within them?