L. J. Matthews, P. M. Butler, “Novelty-Seeking DRD4 Polymorphisms Are Associated with Human Migration Distance Out-of-Africa After Controlling for Neutral Population Gene Structure”, American Journal of Physical Anthropology 145 (2011): 382–389; and Chuansheng Chen et al., “Population Migration and the Variation of Dopamine D4 Receptor (DRD4) Allele Frequencies Around the Globe”, Evolution and Human Behavior 20 (1999): 309–324.
