A paper has been by published by Lordkipanidze et al. (2013) in the journal Science which highlights the unique fossil finds at the Dmanisi palaeoanthropological site, in Georgia, of the cranial and post-cranial remains of 5 Homo erectus individuals. In particular the paper discusses the morphological aspects of the fifth Dmanisi skull, D4500 and associated mandible D2600, as a remarkably well preserved find. Discovered during field work at Dmanisi in 2005, D4500 and D2600 represents one of the best preserved and complete adult skulls of Early Pleistocene Homo fossils so far discovered and described (Lordkipanidze et al. 2013: 326).
The paper in question debates the morphological variation between the cranial remains of the five Homo erectus individuals at Dmanisi, suggesting that there is greater variation in the Homo genus than is typically given credit for. The paper compares the five Dmanisi crania and their morphological variations between the individuals to early and later Homo species hominins (including early African Homo species and Homo neaderthalensis), modern Homo sapiens and extant apes (including Pan troglodytes). The conclusions of the article suggest that there is wide variation within the early Homo palaeodeme of morphological variation, much more than has been noted or given credit for with perhaps too many species being named and described as individual species in the early Homo fossil record. Lordkipanidze et al (2013:330) argue that the Dmanisi collection could represent evidence of the single lineage hypothesis for early Homo. Of course this is a contentious issues and further research is needed, but this is exciting nonetheless.
There has been numerous online blog entries debating the article and its implication for the evolution of the Homo genus. To my mind the articles linked to below perhaps sum up the best reactions and thoughts to the article, although I look forward to further peer-reviewed research being carried out. Outlining the main issues from the article, and the evolutionary mechanism behind the variations present in the Homo genus, is Weiss’s article over at the The Mermaid’s Tale which is informative and exciting. He also discusses the background to the one species hypothesis within Homo which Lordkipanidze et al. (2013) imply could be a possibility as a result of their study of D4500. They also suggest it as a mechanism for phylogenetic continuity across continents for early Homo. John Hawks presents critical comments on the article and evocatively describes just how well D4500 has survived and how beautiful and complete a specimen the individual actually is. In particular Hawks offers his own interesting comments on early Homo evolution and the importance of understanding the many facets of evolution that are at work, including the genetic differences and how modern populations of Homo sapiens often provide poor comparative models for ancient Homo species. At A. P. Van Arsdale’s blog there is a nice breakdown of the article itself, including just why the five crania at Dmanisi are so important and just what their discovery may mean for interpreting the hominin fossil record.
Now to end this brief blog post I think it is only right that I post a picture of the articulated skull of D4500 himself*. It is a beautifully preserved specimen and one worth taking the time to ponder over.
The articulated individual known as D4500 (cranium) and D2600 (mandible) exhibiting a small braincase with a large prognathic face, found at the Georgian site of Dmanisi in 2005. The skull also boasts of one of the best preserved basicranial of any Homo erectus known (Hawks 2013) although the dentition displays that most of the teeth were worn past their crowns. Source: Lordkipanidze et al. (2013: 327).
*It is likely that the individual is a male, but expected a flood of research to take place in the next few years on the Dmanisi individuals and their context within human evolution.
Further Information
- A full list of scientific publications from the Dmanisi palaeoanthropological site can be found here on the official website (though I am unsure how often the site is updated). The website has detailed information on the formation and geology of the site, including the hominins and the different species of fauna that have been found, plus you can still get a place to dig at the actual site!
- Check out The Human Story’s take on a new 2014 article suggesting that there could possibly be two hominin lineages suggested at the Dmanisi site.
Bibliography:
Hawks, J. 2013. The New Skull from Dmanisi. John Hawks Weblog. 18/10/2013.
Lordkipanidze, D., Ponce de León, M. S., Margvelashvili, A., Rak, Y., Rightmire, G. P., Vekua, A. & Zollikofer, C. P. E. 2013. A Complete Skull from Dmanisi, Georgia, and the Evolutionary Biology of Early Homo. Science. 342 (6156): 326-331. (Full article here, email if this doesn’t work).
Van Arsdale, A. P. 2013. The New (Wonderfu) Dmanisi Skull. The Pleistocene Scene- A.P. Van Arsdale Blog. 17/10/2013.
Weiss, K. 2013. How Many ‘Human’ Species are there? Is it even a Real Question? Why does Anybody Care? The Dmanisi Skulls. The Mermaid’s Tale. 21/10/2013.
These Bones Of Mine 