The Dmanisi hominins, Dmanisi people, or Dmanisi man were a population of Early Pleistocene hominins whose fossils have been recovered at Dmanisi, Georgia. The fossils and stone tools recovered at Dmanisi range in age from 1.85 to 1.77 million years old, making the Dmanisi hominins the earliest well-dated hominin fossils in Eurasia and the best preserved fossils of early Homo from a single site so early in time. Though their precise classification is controversial and disputed, the Dmanisi fossils are highly significant within research on early hominin migrations out of Africa. The Dmanisi hominins are known from over a hundred postcranial fossils and five famous well-preserved skulls, referred to as Dmanisi Skulls 1–5.
The taxonomic status of the Dmanisi hominins is somewhat unclear due to their small brain size, primitive skeletal architecture, and the range of variation exhibited between the skulls. Their initial description classified them as Homo (erectus?) ergaster (an otherwise African taxon), or potentially an early offshoot of later Asian H. erectus. The discovery of a massive jaw, D2600, in 2000 led researchers to hypothesize that more than one hominin taxon had been present at the site and in 2002, the jaw was designated as the type specimen of the new species Homo georgicus. Later analyses by the Dmanisi research team have concluded that all the skulls likely represent the same taxon with significant age-related and sexual dimorphism, though this is not a universally held view. In 2006, the team favoured subsuming the taxon under Homo erectus as H. erectus georgicus or H. e. ergaster georgicus. The nomenclature is still debated.
Anatomically, the Dmanisi hominins exhibited a mosaic of traits, possessing some features reminiscent of later and more derived H. erectus and modern humans, while retaining features of earlier Homo and Australopithecus. The length and morphology of their legs was essentially modern and they would have been adapted to long-range walking and running, but their arms were likely more similar to the arms of Australopithecus and modern non-human apes than to later hominins. The Dmanisi hominins would also have differed from later (non-insular) Homo in their small body (145–166 cm; 4.8–5.4 ft) and brain size (545–775 cc), both of which are more comparable to H. habilis than to later H. erectus. Morphological traits unifying all of the skulls, though the degree in which they are pronounced differ, include large brow ridges and faces.
In the Pleistocene, the climate of Georgia was more humid and forested than it is today, comparable to a mediterranean climate. The Dmanisi fossil site was located near an ancient lake shore, surrounded by forests and grasslands and home to a diverse fauna of Pleistocene animals. The favourable climate at Dmanisi might have acted as a refuge for hominins in the Early Pleistocene and it would have been reachable from Africa through the Levantine corridor. Stone tools found at the site are of the Oldowan tradition.
Taxonomy
Research history
Early excavations at Dmanisi
Dmanisi is located in southern Georgia, about 85 kilometres (52.8 miles) from the country's capital, Tbilisi. It was founded as a city in the Middle Ages and has thus been a site of archaeological interest for some time, with a prominent archaeological excavation site being located within the ruins of the old city on a promontory overlooking the Mashavera and Pinazauri rivers. Archaeological excavations began in 1936 on the initiative of historian Ivane Javakhishvili, who directed several expeditions. In 1982, archaeologists at Dmanisi discovered 3 metre (10 ft) deep pits, cut in compact sandy clay. The archaeologists believed the pits were made for some economic purpose in the Middle Ages. After they cleaned them out, they discovered fossilised animal bones on the walls and bottom of the pits. The Georgian Paleobiological Institute of the Academy of Sciences was informed immediately and systematic palaeontological excavations began in 1983, but ended in 1991 on account of financial issues.
During the 1983–1991 excavations, a large amount of animal fossils were collected, alongside some stone tools. The stone tools were quickly noted as highly archaic, far more primitive than other tools found in Eastern Europe. Biostratigraphically (dating through comparisons with fauna at other well-dated sites), they were determined to be from the Late Pliocene to the Early Pleistocene. Every year since 1991, the Georgian palaeontologists, joined by specialists from the Romano-Germanic Museum in Cologne, have undertaken new excavations, completely funded by the Romano-Germanic Museum until 1999.
Discovery of hominin remains
The expedition in 1991 was highly productive, uncovering abundant animal fossils and a considerable quantity of stone tools. On the morning of 25 September, a group of young archaeologists led by Medea Nioradze and Antje Justus uncovered a mandible.
As the heads of the expedition, Georgian archaeologists and anthropologist Abesalom Vekua and David Lordkipanidze (then in Tbilisi) were summoned to the site and on the next morning, the mandible was freed from the rock around it, a complicated process that took nearly an entire day. Once freed, the mandible was unmistakably the jaw of a primate and importantly, it preserved a complete row of teeth with little sign of wear. The lack of wear suggested that the primate would have been young, about 20–24 years old, though its classification was as of yet unknown. After they returned to Tbilisi, the mandible was studied in detail by Vekua, Lordkipanidze and archaeologist Leo Gabunia. It was quickly determined to represent a hominid, though its precise position within the family was unclear. Although a number of primitive features were observed, it was clear that the fossil (now given the designation D211) was the most similar to fossils of Homo, not earlier australopithecines. After prolonged discussion, Vekua and Gabunia came to the conclusion that the Dmanisi hominin was probably an early Homo erectus, and that it represented the earliest Homo outside Africa. This was confirmed once the basalts lying directly below the Pleistocene sediments were determined to be about 1.8 million years old.
Excavations continued at the site, though hominin remains proved to be rare. In 1997, the right third metatarsal bone of a hominin was discovered in the same layer as the jaw. Further discoveries were made in May 1999. Because of long-lasting periods of rainfall, the site was damaged. Archaeologist and expedition member Gocha Kiladze found a thin, coin-sized skull fragment. Kiladze, Vekua, Lordkipanidze, alongside archaeologist Kakha Kakhiani and the head of the 1999 expedition, archaeologist Giorgi Kopaliani, then visited the site and discovered further fragments. With these fragments, they were able to piece together the skull of an archaic human, with broken off teeth and a broken off upper jaw. That same year, a more well-preserved skull was discovered and together, the two skulls allowed for inferences as to the nature and classification of the fossil hominins. The first skull, dubbed Skull 2, was given the designation D2282 and the second skull, Skull 1, was given the designation D2280. After studying the fossils for almost a year, it was determined that they somewhat differed from H. erectus in their jaws and skulls and were closer to the earlier African species H. ergaster (now considered an early African representative of H. erectus by some). The discovery of the two skulls was highly publicised in international media and the Georgian fossils were for the first time widely acknowledged as the earliest known hominins outside of Africa.
Further discoveries
More discoveries followed. In 2000, another hominin jaw (D2600) was discovered, this time at a slightly lower layer (i.e. older) than the rest of the fossils. This jaw was very large and had highly developed posterior molar teeth. The following year, Skull 3 (D2700) and its corresponding jaw (D2735) was discovered, almost perfectly preserved. On account of its erupting wisdom teeth, Skull 3 was determined to be the skull of a subadult. In 2002, the toothless skull of an old individual, Skull 4 (D3444, the associated jaw, D3900, was discovered in 2003) was discovered. Both Skull 3 and Skull 4 were noted as preserving a series of very primitive characteristics. The final skull, Skull 5 (D4500), was discovered in 2005. The skull matched the jaw found in 2000 and the two were concluded as having come from the same individual. The skulls were significant not only in their set of unique features. Skull 5 was the first found completely preserved adult hominin skull from the Early Pleistocene, and Skull 4 is the only toothless hominin discovered in such early sediments.
In addition to the skulls, about a hundred postcranial remains have been discovered. The first postcranial fossil discovered was a third metatarsal bone, recovered in 1997. Postcranial fossils comprise bones from all parts of the body and include parts of the arms, legs, axial skeleton (vertebrae and ribs) and feet. The bones, some of them confidently associated with Skull 3, are from both adolescent and adult individuals.
Together, the fossils at Dmanisi represent the most complete and richest collection of early Homo fossils at a single site with a comparable temporal context. The variability in age (i.e. Skull 3 being subadult and Skull 4 being significantly older) and presumably sex also gives unique insight into the variability in early populations of Homo.
+The Dmanisi SkullsImageSkull & specimen number(s)Cranial capacityDiscoveredPublishedNotesDmanisi Skull 1D2280775 cc19992000Skullcap of an adult individual. Interpreted as male on account of the thick brow ridges and other minor skull features.Dmanisi Skull 2D2282 (mandible D211)650 cc1999(mandible in 1991)2000(mandible in 1995)Gracile features, interpreted as the skull of an adolescent female.Dmanisi Skull 3D2700 (mandible D2735)600 cc20012002Skull of a young individual. Generally gracile morphology, but the upper canine teeth have large crowns and massive roots; making assessing its sex difficult. A handful of traits suggests an interpretation as male to be appropriate.Dmanisi Skull 4D3444 (mandible D3900)625 cc2002(mandible in 2003)2005/2006Skull of an elderly individual that had lost all but one tooth. Interpreted as male.Dmanisi Skull 5D4500 (mandible D2600)546 cc2005(mandible in 2000)2013(mandible in 2002)Skull of an adult individual. Skull 5 is the first completely preserved Early Pleistocene adult hominid skull found. Interpreted as male on account of its massive and prominent cranial features.
Classification The classification of the Dmanisi hominins is disputed and a discussion on whether they represent an early form of H. erectus, a distinct species of their own dubbed H. georgicus or something else entirely are ongoing.
Early attempts at classification
The D211 mandible was described in 1995 by Gabunia and Vekua, who classified it as belonging to a basal population of H. erectus based on dental similarity especially with African specimens (sometimes called H. ergaster). In 1996, palaeoanthropologists Günter Bräuer and Michael Shultz made note of both basal and derived traits, and instead concluded the mandible came from a derived population of H. erectus, despite being so old. In 1998, palaeoanthropologists Antonio Rosas and José Bermúdez De Castro pointed out that such a mosaic anatomy is also documented in H. ergaster, and suggested the classification Homo sp. indet. (aff. ergaster)".