Setting up Ethnobiogeny: Natural Selection Leaves Fresh Footprints on a Canadian Island


In the 3 October 2011 New York Times, Nicholas Wade reports Natural Selection Leaves Fresh Footprints on a Canadian Island. This reporting is based on the PNAS article Evidence for evolution in response to natural selection in a contemporary human population.

As bad as Nicholas Wade has been on race and reporting on anthropology, his recent articles set the stage for something far worse: ethnobiogeny. This is my term for potential research into how ethnically-inflected traits, subject to evolutionary selection, become biological and genetic (see section on Human nature and anthropology and the end of the post on Race Redux).

Two sentences from Wade’s reporting stand out. First, “Over this 140-year period, the age at which a woman had her first child–a trait that is highly heritable–fell to 22 years, from 26.” This just seems strange–age of first child may be highly heritable, but is this really about “natural selection”? Can that actually be more important than socioeconomic change, gendered norms and expectations, access to birth control, and more?

Other articles are a bit more informative. From Recent Human Evolution Detected in Quebec Town History: “Milot recommended that natural selection not be dismissed out-of-hand by demographers and anthropologists. However, while heritability appeared to account for between 30 and 50 percent of first birth age, social factors still accounted for the other 50 to 70 percent.”

A second sentence from Wade: “Dr. Milot said statistical tests allowed the researchers to distinguish between the effects of natural selection and those of cultural practices affecting the age of marriage.” I’m still baffled. Really? And I thought one of the points of our recent research convergence was about a biocultural paradigm, the idea that all these things interact and thus are not amenable to this kind of sorting. Moreover, if we put the 30-50% of heritability from the above quote into the mix, it is not at all clear that this 30-50% is automatically going to be natural selection. What about other evolutionary mechanisms, like sexual selection?

Since his 2010 article on Human Culture, an Evolutionary Force, Nicholas Wade has been at the forefront to trumpet studies about rapid genetic change in humans subject to selection forces. I originally misinterpreted this article as a sign that even the staunch genetic determinist Nicholas Wade was finally making room for culture. But no: he is simply taking us to a whole new level of fine-tuned genetic determinism, when a host of traits will said to have become genetic in the fairly recent past. From the last paragraph of the current article:

In traits that are influenced by many genes, natural selection can act quickly because it does not have to wait for a favorable new mutation to come along. All it needs to do is increase the abundance of some of the genes affecting the trait in question, a process known as a “soft sweep.”

How anthropology responds to this emerging research–the kind of anthropology we choose to do and the stands we choose to take–may become much more important to the field than simply public engagement for its own sake. On this point, have a look at some of the recent contributions to the anthropologies project:

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