The root of the phylogenetic tree of human populations

Although African populations have been shown to be most divergent from anyother human populations, it has been difficult to establish the root of thephylogenetic tree of human populations since the rate of evolutionarychange may vary from population to population owing to the fluctuation ofpopulation size and other factors. However, the root can be determined byusing the chimpanzee as an outgroup and by employing proper statisticalmethods. Using this strategy, we constructed phylogenetic trees of humanpopulations for five different sets of gene frequency data. The data setsused were two sets of microsatellite loci data (25 and 8 loci,respectively), restriction fragment length polymorphism (RFLP) data (79loci), protein polymorphism data (15 loci), and Alu insertion frequencydata (4 loci). All these data sets showed that the root is located in thebranch connecting African and non-African populations, and in the four datasets the root was established at a significant level. These resultsindicate that Africans are the first group of people that split from therest of the human populations.