Relative frequencies of 20 human Y chromosome haplotypes in 10 world regions, and total numbers of males studied per region (last column). The three major haplotypes, A1, B1, and C1, are dashed to indicate the uncertainty in the order of branching points. Haplotypes appearing only once are marked with an asterisk. The principles followed in constructing the tree are described in the text. The mutations leading from one haplotype to another are indicated above each horizontal branch of the tree, and are described in Table 1. In the last row are the numbers of populations (totaling 54, listed in Methods) in which each haplotype has been observed.