Palaeoenvironmental reconstruction of Dmanisi site (Georgia) based on palaeobotanical data

Abstract

The first hominid expansions out of Africa date to the Lower Pleistocene. As environmental changes are widely thought to be correlated to important steps in hominids' history [DeMenocal, P.B., Bloemendal, J., 1995. Plio-Pleistocene subtropical African climate variability and the paleoenvironment of hominid evolution: a combined data-model approach. In: Vrba, E., Denton, G., Burckle, L., Partridge, T. (Eds.), Paleoclimate and Evolution with Emphasis on Human Origins. Yale University Press, New Haven, pp. 262–288; Potts, R., 1998. Environmental hypotheses of hominin evolution. Yearbook of Physical Anthropology 41, 93–136], what kind of environments would they have encountered on their arrival in Eurasian areas? The site of Dmanisi (Lesser Caucasus, Georgia) is well-dated to the very beginning of Matuyama chron (ca. 1.77 Ma), and thus corresponds to one of the oldest dispersal events from Africa into Eurasia. New archaeological investigations of the lower Pleistocene sequences at Dmanisi yielded both human and faunal remains within a secure geochronological context. Although palaeoecological data, based primarily on faunal taxa are well-known, questions remain regarding the palaeoenvironmental and palaeoclimatic contexts of this site. These questions are addressed using multiproxy palaeobotanical analyses (i.e. phytoliths, pollen grains and carpo-remains) on the Dmanisi material. Focuses on several profiles help to reconstruct the distribution and evolution of vegetation at the site over time. The results show a composite temperate ecosystem with grass species being well-represented. In the mid-part of the sequence, evidence of enhanced aridity contemporaneous with hominid occupation is recorded. Although these reconstructed environments are similar to African savannah because of the abundance of grasses, arid conditions and the abundance of large mammal species, they differ with respect to the vegetation taxa, which are mostly composed of temperate plants.