Dmanisi, Variation, and Systematics of Early Homo

Our genus evolved in Africa, and its members were confined to that continent for a long period. The site of Dmanisi in the Georgian Caucasus records the oldest known occupation of Eurasia, beginning ca. 1.85 Ma ago. At least five individuals are documented from skulls and postcranial bones preserved within a thin sedimentary succession, and there is archaeological and taphonomic evidence relating to the life ways of the Dmanisi hominins. A shared anatomical bauplan, comparisons of variation in craniofacial characters, and comprehensive resampling analyses suggest that the Dmanisi sample cannot reasonably be partitioned on morphometric grounds. A single taxon is present at the site. The paleobiological significance of the Dmanisi assemblage remains controversial. The fossils can most reasonably be attributed to Homo erectus, but several of the skeletons display primitive anatomy. Expanding the known H. erectus hypodigm has the effect of increasing the level of variation observed within this highly polytypic species. The boundaries between H. erectus and other early Homo taxa become less distinct, making it difficult to identify diagnostic traits. Such reassessment of characters hitherto deemed taxonomically important bears critically on the recognition of diversity in Plio-Pleistocene settings. Overall, it is the apparent overlap between groups evolving >2.0 to 1.0 Ma ago, rather than the presence of obvious species-level diversity, that characterizes the emergence of the Homo clade.