Dmanisi (Georgia)

Ancient Hominins in the Republic of Georgia

Dmanisi Excavations, 2007
Georgian National Museum

Dmanisi is the name of a very old archaeological site located in the Caucasus of the Republic of Georgia, about 85 kilometers (52 miles) southwest of the modern town of Tbilisi, beneath a medieval castle near the junction of the Masavera and Pinezaouri rivers. Dmanisi is best known for its Lower Paleolithic hominin remains, which demonstrate a surprising variability which has yet to be fully explained.

Five hominid fossils, thousands of extinct animal bones and bone fragments, and over 1,000 stone tools have been found at Dmanisi to date, buried in about 4.5 meters (14 feet) of alluvium. The stratigraphy of the site indicates that the hominin and vertebrate remains, and the stone tools, were laid into the cave by geological rather than cultural causes.

Dating Dmanisi

The Pleistocene layers have been securely dated between 1.0-1.8 million years ago (mya); the types of animals discovered within the cave support the early part of that range. Two nearly complete hominid skulls were found, and they were originally typed as early Homo ergaster or Homo erectus. They appear to be most like African H. erectus, as those found in Koobi Fora and West Turkana, although some debate exists. In 2008, the lowest levels were redated to 1.8 mya, and upper levels to 1.07 mya.

The stone artifacts, primarily made of basalt, volcanic tuff, and andesite, are suggestive of Oldowan chopping tool tradition, similar to tools found at Olduvai Gorge, Tanzania; and similar to those found at Ubeidiya, Israel. Dmanisi has implications for the original peopling of Europe and Asia by H. erectus: the site's location is support for our ancient human species leaving Africa along the so-called "Levantine corridor."

Homo Georgicus?

In 2011, scholars led by excavator David Lordkipanidze debated (Agustí and Lordkipanidze 2011) the assignment of the Dmanisi fossils to Homo erectus, H. habilis, or Homo ergaster. Based on the brain capacity of the skulls, between 600 and 650 cubic centimeters (ccm), Lordkipanidze and colleagues argued that a better designation might segregate Dmanisi into H. erectus ergaster georgicus. Further, the Dmanisi fossils are clearly of African origin, as their tools conform to Mode One in Africa, associated with Oldowan, at 2.6 mya, some 800,000 years older than Dmanisi. Lordkipanidze and colleagues argued that humans must have left Africa much earlier than the age of the Dmanisi site.

Lordkipanidze's team (Ponzter et al. 2011) also report that given microwave textures on molars from Dmanisi, the dietary strategy included softer plant foods such as ripe fruits and possibly tougher foods.

Complete Cranium: and New Theories

In October of 2013, Lordkipanidze and colleagues reported on a newly discovered fifth and complete cranium including its mandible, along with some startling news. The range of variation among the five crania recovered from the single site of Dmanisi is astonishing. The variety matches the entire range of variation of all the Homo skulls in evidence existing in the world about 2 million years ago (including H. erectus, H. ergaster, H. rudolfensis, and H. habilis). Lordkipanidze and colleagues suggest that, rather than considering Dmanisi as a separate hominid from Homo erectus, we should keep the possibility open that there were only one species of Homo living at the time, and we should call it Homo erectus. It is possible, say the scholars, that H. erectus simply exhibited a much larger range of variation in skull shape and size than, say, modern humans do today.

Globally, paleontologists agree with Lordkipanidze and his associates that there are striking differences among the five hominid skulls, particularly the size and shape of the mandibles. What they disagree on is why that variation exists. Those who support Lordkipanidze's theory that DManisi represents a single population with a high variability suggest that the variability results from a pronounced sexual dimorphism; some as yet unidentified pathology; or age-related changes—the hominids appear to range in age from adolescence to old age. Other scholars argue for the possible co-existence of two different hominids living at the site, possibly including the H. georgicus first suggested.

It's a tricky business, retooling what we understand of evolution, and one that requires the recognition that we have very little evidence from this period so long ago in our past and that evidence needs to be reexamined and reconsidered from time to time.

Archaeology History of Dmanisi

Before it became a world-renowned hominid site, Dmanisi was known for its Bronze Age deposits and a medieval period city. Excavations within the medieval site in the 1980s led to the older discovery. In the 1980s, Abesalom Vekua and Nugsar Mgeladze excavated the Pleistocene site. After 1989, excavations at Dmanisi were led in collaboration with the Römisch-Germanisches Zentralmuseum in Mainz, Germany, and they continue to this day. A total area of 300 square meters has been excavated to date.

Sources:

Bermúdez de Castro JM, Martinón-Torres M, Sier MJ, and Martín-Francés L. 2014. On the Variability of the Dmanisi Mandibles. PLOS ONE 9(2):e88212.

Lordkipanidze D, Ponce de León MS, Margvelashvili A, Rak Y, Rightmire GP, Vekua A, and Zollikofer CPE. 2013. A complete skull from Dmanisi, Georgia, and the evolutionary biology of early Homo. Science 342:326-331.

Margvelashvili A, Zollikofer CPE, Lordkipanidze D, Peltomäki T, and Ponce de León MS. 2013. Tooth wear and dentoalveolar remodeling are key factors of morphological variation in the Dmanisi mandibles. Proceedings of the National Academy of Sciences 110(43):17278-17283.

Pontzer H, Scott JR, Lordkipanidze D, and Ungar PS. 2011. Dental microwear texture analysis and diet in the Dmanisi hominins. Journal of Human Evolution 61(6):683-687.

Rightmire GP, Ponce de León MS, Lordkipanidze D, Margvelashvili A, and Zollikofer CPE. 2017. Skull 5 from Dmanisi: Descriptive anatomy, comparative studies, and evolutionary significance. Journal of Human Evolution 104:5:0-79.

Schwartz JH, Tattersall I, and Chi Z. 2014. Comment on “A Complete Skull from Dmanisi, Georgia, and the Evolutionary Biology . Science 344(6182):360-360.Early of Homo

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Hirst, K. Kris. "Dmanisi (Georgia)." ThoughtCo, Aug. 25, 2020, thoughtco.com/dmanisi-lower-paleolithic-site-170715. Hirst, K. Kris. (2020, August 25). Dmanisi (Georgia). Retrieved from https://www.thoughtco.com/dmanisi-lower-paleolithic-site-170715 Hirst, K. Kris. "Dmanisi (Georgia)." ThoughtCo. https://www.thoughtco.com/dmanisi-lower-paleolithic-site-170715 (accessed March 29, 2024).