EVOLUTIONARY RELATIONSHIPS OF HUMAN-POPULATIONS ON A GLOBAL-SCALE

Using gene frequency data for 29 polymorphic loci (121 alleles), we co nducted a phylogenetic analysis of 26 representative populations from around the world by using the neighbor-joining (NJ) method. We also co nducted a separate analysis of 15 populations by using data for 33 pol ymorphic loci. These analyses have shown that the first major split of the phylogenetic tree separates Africans from non-Africans and that t his split occurs with a 100% bootstrap probability. The second split s eparates Caucasian populations from all other non-African populations, and this split is also supported by bootstrap tests. The third major split occurs between Native American populations and the Greater Asian s that include East Asians (mongoloids), Pacific Islanders, and Austra lopapuans (native Australians and Papua New Guineans), but Australopap uans are genetically quite different from the rest of the Greater Asia ns. The second and third levels of population splitting are quite diff erent from those of the phylogenetic tree obtained by Cavalli-Sforza e t al. (1988), where Caucasians, Northeast Asians, and Amerindians form the Northeurasian supercluster and the rest of non-Africans form the Southeast Asian supercluster. One of the major factors that caused the difference between the two trees is that Cavalli-Sforza et al. used u nweighted pair-group method with arithmetic mean (UPGMA) in phylogenet ic inference, whereas we used the NJ method in which evolutionary rate is allowed to vary among different populations. Bootstrap tests have shown that the UPGMA tree receives poor statistical support whereas th e NJ tree is well supported. Implications that the phylogenetic tree o btained has on the current controversy over the out-of-Africa and the multiregional theories of human origins are discussed.