Recent investigations at the Dmanisi Site in the Republic of Georgia have yielded associated fossils of Homo ergaster, a lithic assemblage of Oldowan (Mode I) technology, and a rich vertebrate fauna correlative with the Late Villanyian-Early Biharian biozones of Europe. Geochronologic and paleomagnetic data indicate an age of ca. 1.7 Ma for the site, making Dmanisi the oldest firmly dated occurrence of humans in Eurasia. Paleoenvironmental reconstructions for the period bracketing the Dmanisi occupations are crucial for intepreting the colonization of and Pleistocene adaptations to the Caucasus region. Steep bioclimatic gradients, controled by elevation and zonal trends, coupled with longer-term environmental changes, signify variable yet persistent Plio-Pleistocene occupation potentials. Tectonically controlled orogenesis, volcanism and Black-Caspian Sea connections have created a complex yet rich stratigraphic framework for investigating and dating human occupation sites and their paleoenvironmental contexts. The geologic and biotic evolution of the Caucasus and its central geographic position, all signify outstanding potentials for continuing advances in research focused on the earliest Eurasian cultures.