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letters: Jeffrey H. Schwartz;, Leo Gabunia, Abesalom Vekua, and David Lordkipanidze Taxonomy of the Dmanisi Crania Science 2000; 289: 55b-56b [Full text]

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The Taxonomy of Dmanisi Crania: Crucial Consequences for Hominid Taxonomy

Lorenzo Rook   (15 September 2000)

The Taxonomy of Dmanisi Crania: Crucial Consequences for Hominid Taxonomy 15 September 2000
Lorenzo Rook, Associate Professor Earth Sciences Department, University of Florence (Italy) Respond to this E-Letter: Re: The Taxonomy of Dmanisi Crania: Crucial Consequences for Hominid Taxonomy	Recently the recovery of two hominid crania from the Early Pleistocene site of Dmanisi in Georgia was reported in Science (1). The importance of these Homo findings, associated with an abundant and exceptionally well-preserved mammal assemblage in a site dated at 1.7 million years ago (Ma) (2), is even more crucial than what is underlined by Gabunia and co- authors (1) and in the discussion between Schwartz and Gabunia et al. here. The human remains from Dmanisi represent the oldest hominids yet found in Eurasia and, at present, the morphological comparisons either with African or Asiatic Homo skulls and mandibles does not allow the allocation to any defined species (1). The two skulls from Dmanisi look so different that Schwartz suggests they represent "intertaxic rather than intrapopulational differences." Taxonomy of fossil hominids is often based on single specimens from localities separated in space and time. Emblematic is the fact that no agreement exist among paleoanthropologists on what is Homo ergaster. Of course, it is the mandible KNM ER992 (3), but no other African specimen is clearly comparable with the type specimen, and the same is true for Homo erectus, as Schwartz points out. Why is hominid taxonomy so difficult and debated? The Dmanisi specimen gives us an answer: We know so little about the intraspecific variability that each isolated finding from a different locality appears to be a different species. Actually, there is something wrong in the usual approach to hominid alpha- taxonomy. The strict morphological approach, consisting of comparing lists of characters derived from detailed morphological analyses applied to the two skulls from a single site that clearly yielded remains of a single population (2), would lead to the odd conclusion that the two skulls are representative of intertaxic differences. In light of this conclusion, what is the real value of so many species in the early-middle Pleistocene of the Old World, H. ergaster, H. erectus, H. antecessor, H. heidelbergensis……? As Gabunia et al. stress in their response, human evolutionary diversity is usually overlooked in systematics. The Dmanisi sample thus is significant in highlighting the need for a more cautious approach to hominid taxonomy. This finding shows how intrapopulation variability plays a crucial role in defining the mosaic of morphologies within the evolutionary history of the genus Homo, and it highlights the need for a new perspective in the approach to hominid taxonomy. References 1. L. Gabunia et al., Science 288, 1019 (2000) 2. L. Gabunia et al., Grabungsergebnisse Archeolog. Korrespond. 29/4, 451 (1999) 3. C. Groves and V. Mazak, Casopis Mineral. Geol. 20, 225 (1975)