Mitochondrial COII Sequences

The aim of this study is to measure human mitochondrial sequence variability in the relatively slowly evolving mitochondrial gene cytochrome oxidase subunit II (CO11 ) and to estimate when the the human common ancestral mitochondrial type existed. New CO11 gene sequences were determined for five humans (Homo sapiens), including some of the most mitochondrially divergent humans known; for two pygmy chimpanzees (Pan par&us); and for a common chimpanzee (P. troglodytes). CO11 sequences were analyzed with those from another relatively slowly evolving mitochondrial region (ND4-5 ). From class 1 (third codon position) sequence data, a relative divergence date for the human mitochondrial ancestor is estimated as 1/27th of the human-chimpanzee divergence time. If it is assumed that humans and chimpanzees diverged 6 Mya, this places a human mitochondrial ancestor at 222,000 years, significantly different from 1 Myr (the presumed time of an H. erectus emergence from Africa). The mean coalescent time estimated from all 1,580 sites of combined mitochondrial data, when a 6-Mya human-chimpanzee divergence is assumed, is 298,000 years, with 95% confidence interval of 129,000-536,000 years. Neither estimate is compatible with a I-Myr-old human mitochondrial ancestor. The mitochondrial DNA sequence data from CO11 and ND4-5 regions therefore do not support this multiregional hypothesis for the emergence of modern humans.