Over the course of human evolution, the human lineage made a transition from a geographically constrained population endemic to Africa to the most widespread mammalian species occupying the entire globe. Dr. Martha Tappen's NSF funded research focuses on questions that will illuminate the cause and nature of the first expansion out of Africa at the best preserved early archaeological site out of Africa, Dmanisi in Georgia. There an international research team has uncovered over 60 Homo erectus sensu lato fossils, thousands of fossils of extinct mammals, and Oldowan stone tools in tight spatial and stratigraphic association. Along with the coherent dates of at least 1.77 Myr, the evidence from the site forms the foundation on which anthropologists anchor hypotheses of the earliest biogeographic spread of humans.
There is much that remains to be learned from the site. Dr. Tappen will undertake new analyses of the previously excavated materials from Dmanisi as well as new materials being uncovered in current excavations, aimed at understanding the formation of the site itself (e.g. why are there so many fossils in one spot?). This work is a primary step required to base all further interpretations of hominin behavior and habitats at the site. The work will be conducted at the site itself and in the Georgian National Museum in collaboration with Dmanisi team, especially Drs. David Lordkipanidze and Maia Bukhsianidze of the Georgian National Museum and Dr. Reid Ferring of the University of North Texas. The specific aims are to : 1) curate, protect, and organize the beautifully preserved fossil mammals for this research and that of future workers; 2) make precise identification of taxon and skeletal element on specimens not yet analyzed from the last few years of excavations, to create quantitative measures of skeletal elements and taxonomic abundance; 3) complete taphonomic observations on the assemblage (e.g. looking at tooth marks and tools marks, bone breakage patterns, ages of death); 4) test specific hypotheses about the formation and accumulation of the bone assemblage from the different areas and stratigraphic layers of the site.
The intellectual merit of this work lies in documenting, preserving, and analyzing the primary contextual evidence of the Dmanisi site, required for understanding the dating, habitats and behaviors of the hominins that lived there. From this primary stratigraphic, taxonomic, taphonomic and spatial evidence several hypotheses will be tested, such as: 1) the importance of meat, hunting and/or scavenging for occupying the higher latitudes throughout the winter; 2) the nature of hominin-carnivore interactions at this time period; and 3) questions of Homo erectus' habitat breadth. This thorough analysis of the fauna and its context involves two levels of questions, one set specific to the formation of the Dmanisi site and hominin behaviors that may be preserved at the site itself, and the other a broader set of questions regarding the circumstances of the first expansion of hominins out of Africa in general, as well as the meaning of the fossil mammals in terms of biostratigraphy, biogeography, and environments.
The broader impacts of this project go well beyond just the research results. This project will help to further strengthen times between America and Georgia. The research group will bring an American graduate student to Georgia each year to train in basic zooarchaeological methods and mapping for each of the three years of the grant, and it will also train Georgian students in paleontological and zooarchaeological methods. The proper curation and cataloging of the fossils from Dmanisi will be a long standing and important contribution to research and education.
Humans have the remarkable capacity to live in many different environments, from habitats in the frigid north, to temperate and tropical forests, savannas, and hot deserts. Other primates have relatively limited ecological ranges. We are able to live in such a broad range of environments for many reasons, including our broad diets and social behaviors such as cooperation, sharing, and trade. But when, where, and how did these behaviors come about? Our ancestorsâ€™ earliest expansion Out of Africa into Eurasia is documented at the Paleolithic site of Dmanisi, in the country of Georgia, just south of the Caucuses Mountains. At Dmanisi, fossils of early Homo erectus are preserved associated with simple stone tools and fossils of extinct mammals. The intellectual merit of this NSF funded project is documenting and analyzing the context of these fossils in excavation, identifying the species, and measuring the modifications to fossil bones. This work builds our understanding of why and how early Homo was able to live at this relatively northern latitude-- when for millions of years before they could not. Dmanisi has become the anchor point for understanding the capabilities of Homo at 1.8-1.7 million years ago. The work shows that the Homo spread out of Africa independently, and not with a broad interchange of other large mammals between the continents. It implies new adaptive behaviors were developing within Homo at this time, rather than the spread simply being an ecological spread of African habitats to northern latitudes. Yet the fossil Homo specimens from Dmanisi still have relatively small brains and body size. We have documented cut marks made by stone tools on mammal bones such as extinct bison, deer, wolves and even mammoth-- indicating meat of large game was an important source of food. Yet most of the bone modifications from the site were caused by large carnivores such as large hyenas, sabertooths and other large cats as well as a small ancestor of wolves. These associations truly advance our understanding of early stages of Homo erectus and have already transformed hypotheses by anthropologists, who are intuiting even early biogeographic expansions will yet be discovered. This work also has had broader impacts. It has broadened the participation for women in science, for both the PI and the main Georgian paleontologist working on the project are female. It has deepened collaboration with American and Georgian researchers, truly a benefit to both societies, because it has led to exchange of ideas and methods between our communities, and has fostered good will. We have preserved the unique fossil assemblage through careful curation and documentation so that it will be preserved for future workers. American undergraduate and graduate students were brought to Georgia and gained invaluable experience on excavation on a multinational expedition and so have increased their understanding other peoples and cultures. Hundreds of undergraduates at the University of Minnesota have been taught about the scientific methods of hypothesis building, data gathering, analysis, and interpretation through case studies of this research.