Tracing Our Lineage: Molecular Contributions to the Construction of the Human Phylogeny

Abstract

One of the most novel and important contributions to biological anthropology in the last two decades has been the implementation of the techniques of molecular genetics to address some of the field’s fundamental debates. The ordering of the extant hominids into monophyletic clades has long been a source of contention, with human-chimpanzee, human-gorilla, and human-orangutan clades being proposed in various studies. An expanding genetic analysis culminating in over 20,000 sequence alignments of all extant hominids has shown that chimpanzees and humans form a monophyletic clade, the closest relative of which is the gorilla. Since the discovery of the first Neandertal specimens there has also been a sometimes vicious dichotomy between those that advocate interbreeding between modern humans and Neandertals (The Multiregional Continuity Model), and those who maintain that modern humans replaced all other hominids with absolutely no interbreeding (The Recent African Origin Model). Analysis of mitochondrial DNA accompanied by a draft sequence of the Neandertal nuclear genome has called into question the validity of both paradigms and promoted the emergence of a compromise in the form of The Partial Replacement Model. Finally, the debate on the division of the human species into geographic races has been raging for centuries. Genetic comparisons between populations demonstrate that the total amount of human variation is in fact very small and provides no basis for the concept of biologically distinct races. The contributions of molecular genetics to biological anthropology are inestimable and will only continue to increase as technological advances are made.