A genomic survey of world populations by Dr. Feldman, Noah Rosenberg and colleagues in 2002 showed that people clustered genetically on the basis of small differences in DNA into five groups that correspond to the five continent-based populations: Africans, Australian aborigines, East Asians, American Indians and Caucasians, a group that includes Europeans, Middle Easterners and people of the Indian subcontinent. The clusterings reflect “serial founder effects,” Dr. Feldman said, meaning that as people migrated around the world, each new population carried away just part of the genetic variation in the one it was derived from.
Humans migrate quickly and our rate of gene flow between populations is much higher than between populations of great apes. Gene flow decreases diversity and genetically homogenizes a species, our species is a great case example of that effect…of the 3 billion base pairs in the human genome, there are 38 million variants of difference within our species… most variants appear in only one or two people or populations. Founder effect dictates degrees of human genetic diversity within our species. Genetic Origins.