Primate η-globin DNA sequences and man's place among the great apes

Abstract

Molecular studies indicate that chimpanzee and gorilla are the closest relatives of man (refs 1–7 and refs therein). The small molecular distances found point to late ancestral separations2,4,7, with the most recent being between chimpanzee and man, as judged by DNA hybridization3,8. Kluge9 and Schwartz10 contest these conclusions: morphological characters group a chimpanzee–gorilla clade with the Asian ape orang-utan in Kluge's cladistic study and with an orang-utan–human clade in Schwartz's study. Clearly, extensive sequencing of nuclear DNA is needed to resolve by cladistic analysis the branching order within Hominoidea11. Towards this goal, we are sequencing orthologues of the primate ψη-globin locus12,13. Here, we compare the newly completed sequences of orang-utan and rhesus monkey with human, chimpanzee, gorilla, owl monkey, lemur and goat orthologues. Our findings substantially increase the evidence indicative of a human–chimpanzee–gorilla clade with ancestral separations around 8 to 6 Myr ago. We also verify that neutral hominoid DNA evolved at markedly retarded rates.