They have missed the point, responds Galor, a prominent economist whose work examines the ancient origins of contemporary economic factors. “The entire criticism is based on a gross misinterpretation of our work and, in some respects, a superficial understanding of the empirical techniques employed,” he says. Galor and Ashraf told Nature that, far from claiming that genetic diversity directly influences economic development, they are using it as a proxy for immeasurable cultural, historical and biological factors that influence economies. “Our study is not about a nature or nurture debate,” says Ashraf.
“It seems like the devil is in the interpretation more than the actual application of the statistics,” says Sohini Ramachandran, a population geneticist at Brown University who provided the genetic data for the study. She adds that Galor and Ashraf used estimates of genetic diversity that she and her colleagues specifically developed to overcome many of the confounding factors caused by the overlapping genetic and cultural histories of neighbouring countries.
Galor and Ashraf are not the first economists to use genetic-diversity data. Spolaore has also found that the differences in genetic diversity between countries can predict discrepancies in their level of economic development. But he is clear that this is not necessarily a causal relationship: “In my view it’s not genetic diversity itself that is responsible for this correlation,” he says. “A lot of this could be culture.”
Some say that the field needs a dose of rigour. Many studies linking genetic variation to economic traits make basic methodological errors, says Daniel Benjamin, a behavioural economist at Cornell University in Ithaca, New York. He is part of the Social Science Genetics Association Consortium, a group that brings together social scientists, epidemiologists and geneticists to improve such studies. Problems that medical geneticists have known about for years — such as those stemming from small sample sizes — crop up all too often when economists start to work with the data, he says.
For instance, while searching for genetic associations with factors such as happiness and income in a study of 2,349 Icelanders, Benjamin and his colleagues found a stati-stically significant association between educational attainment and a variant in a gene involved in breaking down a neurotransmitter molecule. But the researchers could not replicate this association in three other population samples — a test for false positives that is standard practice in medical genetics — and the team now has reservations about the association. If the field is to develop fruitfully, “I think it’s essential for us to have geneticists involved”, says Benjamin. “We couldn’t do it without their help and insight.”
This article is reproduced with permission from the magazine Nature. The article was first published on October 10, 2012.