Genetic distance from individuals in the Perlegen data to the three continentally defined HapMap groups. Individuals of similar geographic origin cluster together. African-Americans from the Perlegen data set lie in between the HapMap Yoruba and European-Americans, but are much closer to the Yoruba.
Allocco et al. BMC Genomics 2007 8:68 doi:10.1186/1471-2164-8-68