Magazine article The Wilson Quarterly

Double Helix Destiny

Magazine article The Wilson Quarterly

Double Helix Destiny

Article excerpt

THE SOURCE: "The 'Out of Africa' Hypothesis, Human Genetic Diversity, and Comparative Economic Development" by Quamrul Ashraf and Oded Galor, in American Economic Review, Feb. 2013.

WHAT GIVES RICH SOCIETIES THEIR MOJO? Scholars who look for the roots of economic development offer an array of answers: Culture, history, or geography push a country toward prosperity, they claim.

Quamrul Ashraf and Oded Galor, economists at Williams College and Brown University, respectively, propose an entirely different explanation: genetic diversity. They say the range of a given population's genes--determined 70,000 to 90,000 years ago when humans first journeyed out of East Africa--played a decisive role in determining which lands would hit the economic jackpot.

In a process known as the serial founder effect, populations closer (via land migration routes) to modern-day Ethiopia, where the earliest evidence of Homo sapiens has been found, had higher levels of genetic diversity than groups that settled farther away. The nearer societies had more "founders"--or early settlers--and therefore more genetic variation. When smaller groups peeled off and ventured into Europe and Asia, they carried a smaller gene pool with them. It shrank further when humans trekked to the Americas.

This made all the difference. Societies flourish when their populations have just enough genetic diversity, but not too much. (Geneticists gauge genetic diversity with "expected heterozygosity," which measures the likelihood that two people within a group will have, say, a difference in eye color or some other heritable trait.) Genetically diverse societies are more likely to cook up new technologies; people with varying traits develop different specialties and work in complementary ways.

But heterozygosity comes with tradeoffs. Kin selection theory suggests that the more closely related people are genetically, the more likely they are to cooperate with one another. More diversity equals less cooperation. While spurring innovation and production, genetic diversity simultaneously "raises the likelihood of disarray and mistrust, reducing cooperation and disrupting the socioeconomic order." On the other end of the spectrum, low genetic diversity promotes high levels of public trust and economic efficiency. Yet the gene pool does not vary enough to kick development into high gear.

Thanks to the path taken by the earliest humans out of Africa, Asian and European populations that developed at least 3,000 miles from humanity's birthplace hit the diversity sweet spot. In contrast, "the low degree of diversity among Native American populations and the high degree of diversity among African populations have been detrimental forces in the development of these regions," Ashraf and Galor write. …

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