Reconstructing Human Origins

[Disclaimer: I am a co-author of the research discussed below, but I felt it would be of interest to the community particularly as it may help clarify hominid relationships]

A paper by Charlie Lockwood (of University College London), Bill Kimbel (of Arizona State University) and I (also of ASU) just published in this weeks Proceedings of the National Academy of Sciences titled “Morphometrics and hominoid phylogeny: Support for a chimpanzee-human clade and differentiation among great ape subspecies,” finds a strong agreement beween morphological and genetic variation among great apes when using a specific bone of the skull (the temporal) and a specific set of techniques (geometric morphometrics and distance-based tree generation). As the temporal bone is often well preserved in fossil hominids, we suggest that this combination of techniques may allow the inference of accurate phylogenies (i.e. congruent with genetic data) from such material. All very exciting, as it re-affirms the importance of morphological data in the phylogentic analysis of extinct hominids and opens up a range of possibilities for future studies, in that we feel reasonably confident that morphological trees thus derived using fossil material have a strong relationship to the patterns we would get if genetic data were available from the fossils.

The abstract reads:

Taxonomic and phylogenetic analyses of great apes and humans have identified two potential areas of conflict between molecular and morphological data: phylogenetic relationships among living species and differentiation of great ape subspecies. Here we address these problems by using morphometric data. Three-dimensional landmark data from the hominoid temporal bone effectively quantify the shape of a complex element of the skull. Phylogenetic analysis using distance-based methods corroborates the molecular consensus on African ape and human phylogeny, strongly supporting a Pan-Homo clade. Phenetic differentiation of great ape subspecies is pronounced, as suggested previously by mitochondrial DNA and some morphological studies. These results show that the hominoid temporal bone contains a strong phylogenetic signal and reveal the potential for geometric morphometric analysis to shed light on phylogenetic relationships.

A EurekAlert press release (with quotes from the authors!) is available. Full text of the paper is online at my website, where you will also find a more technical paper examining the techniques that was published in the Journal of Anatomy in December 2002.