Benjamin Campbell (1), Michael Sorenson (2) and Dan Eisenberg (3) Webcast : Read the Summary

Variation in dopamine receptor D4 and the origins and migration of modern humans

Thought to arise approximately 50,000ybp around the time of expansion out of Africa, the 7R allele of the DRD4 dopamine receptor provides an important case study for the origins and migration of modern humans. The 7R allele is known to be associated with ADHD and population variation in the frequency of the allele has been suggested to effects of either

1) the propensity of individuals to migrate;
2) the degree to which impulsive and non-complaint males have higher reproductive success in different cultural settings.

While the 7R allele has been associated with reproductive intentions among individuals of European ancestry, neither of these hypotheses has been tested directly in non-agricultural populations. The Ariaal, pastoralists of Kenya provide an interesting test case. The Ariaal are polygynous, and contain settled and nomadic groups. We collected hair samples from 200 Ariaal men to determine the frequency of the 7R alleles. We compared the frequency of the 7R allele in settled vs. nomadic males to determine its association with migratory behavior, as well as difference between polygynous and monogamous males to test its association with reproduction. The implications of these results for behavioral change with the origins of modern humans are discussed.