The results of previous systematic studies of Old World monkeys using morphological and molecular techniques have been in disagreement. Many possible relationships have been proposed for members of the tribe Papionini (baboons, drills, mandrills, macaques and mangabeys), but no previous studies have been based on nucleotide sequences. The question of these relationships will be addressed using cytochrome c oxidase (COII) mitochondrial gene nucleotide sequences to derive phylogeneic hypotheses. This gene is ideal for a study of Papionini systematics due to its rate of change, lack of recombination, and ease of study. The results of this study should provide two kinds of valuable information. First, a better understanding of the phyletic relationships among Old World monkeys should be possible. Second, by comparing Papionini gene sequences to those of other primates and non-primate mammals, a better understanding will emerge of the rate of change in the mitochondrial genome. This is important since the rate affects conclusions regarding the order and timing of branching events, and consequently interpretations of the fossil record both for these primates and for other primate lineages.
