A group of Harvard academics have penned a short response to Ashraf and Galor’s forthcoming American Economic Review paper, The Out of Africa Hypothesis, Human Genetic Diversity and Comparative Economic Development.

Ashraf and Galor argue that economic development is affected by genetic diversity, which increases innovation but also increases conflict and distrust. This leads to an optimum “goldilocks” level of diversity, with genetically diverse Africans and less genetically diverse native Americans falling on either side of that optimum.

The Harvard academics suggest that the findings of the paper are scientifically flawed and that Ashraf and Galor “misuse genetic, evolutionary, archaeological, historical and cultural data”. They question the causal mechanism proposed by Ashraf and Galor and their statistical treatment. I will give my views on the causative mechanisms when I write a full post on the paper (probably to coincide with its publication). However, the statistical issue is interesting. The academics write:

The argument is also statistically flawed by treating genetic data as each population having an entirely independent history both from a genetic and from a historical point of view, when in fact, they are highly correlated and inextricably entangled with genetic population structure and with contingent historical events. Such haphazard methods and erroneous assumptions of statistical independence could equally find a genetic cause for the use of chopsticks.

This argument is similar to the statement that the various independent origins of agriculture are not actually “independent”. Populations in each region may have developed the specific idea of agriculture themselves, but they had a shared cultural and evolutionary history and their state at the time of the development of agriculture reflected elements of that shared history. However, in the limit, there is little of interest in the social sciences that is truly independent, so the question is what level of independence is required and whether statistical techniques can draw out relationships that are not spurious. Still, the risks presented by population structure in research such as this is very real.

In the last part of the letter, the Harvard academics reflect on the implications of the research and raise the common argument that this area should not be investigated due to “the potential to be misused with frightening consequences to justify indefensible practices such as ethnic cleansing or genocide.” I do not find this argument compelling, and consider that there is a need for robust, scientific exploration of an area that will continue to be debated with or without that research.

*Postscript: I somehow missed it, but Ashraf and Galor have written a response (Update: which now seems to have been taken down). Thanks Vincenzo for the pointer.

My posts on Ashraf and Galor’s paper on genetic diversity and economic growth are as follows:

  1. A summary of the paper methodology and findings

  2. Does genetic diversity increase innovation?

  3. Does genetic diversity increase conflict?

  4. Is genetic diversity a proxy for phenotypic diversity?

  5. Is population density a good measure of technological progress?

  6. What are the policy implications of the effects of genetic diversity on economic development?

  7. Should this paper have been published?

Other debate on this paper can also be found hereherehere and here.