Late Pliocene Hominid Bahavior and Paleoecology at Kanjera South, Africa

Cuny Queens College, Flushing NY

Investigators

Abstract

With National Science Foundation support, Dr. Tom Plummer and colleagues will conduct two field seasons of excavation at Kanjera South, southwestern Kenya. The team brings together specialists in archaeology, paleontology, paleoecology and geology to conduct an interdisciplinary investigation of the behavior and paleoecology of hominids forming early archeological (Oldowan) sites. The appearance of Oldowan archeological sites at c. 2.5 million years ago (Ma) reflects a profound adaptive shift in human evolution, the incorporation of large mammal tissue into the diet. The proposed project will be the first to carry out a detailed study of site formation processes at Oldowan sites older than 2.0 Ma, using a wide range of traditional and innovative methodologies. Excavations in 1996 and 1997 located rich concentrations of artifacts and fossils in c. 2.2 Ma deposits in the Southern Exposures at Kanjera. Over 1,000 stone tools and thousands of fossils were collected in carefully controlled taphonomic excavations. Documentation of relatively high archeological densities in three beds at two of five sites along a 70m transect suggests that hominid activity was spatially focused for a considerable length of time. Preliminary lab analysis has identified hominid marrow processing and carnivore damage to bone, as well as several artifact refits. Stable isotopic chemistry of paleosol carbonates and high equid frequencies indicate Oldowan hominid activities in a novel (open) paleohabitat. A high proportion of small, immature mammals is suggestive of small mammal hunting while medium to very large mammal remains (including a potentially butchered hippopotamus) may have been scavenged. Hominid transport of artifacts and raw material selectivity is suggested by lithic analysis. Expanding the samples of excavated material will allow reconstruction of hominid activities within their paleoecological context at Kanjera and facilitate meaningful comparisons with other large Oldowan site assemblages, particularly those from Olduvai Gorge, Tanzania and the Lake Turkana basin, Kenya and Ethiopia. Faunal analysis will provide information on hominid procurement and processing of animals as well as the role of carnivore activity in assemblage formation. Lithic analysis will document local technological characteristics and hominid transport behavior as well as the tasks chert artifacts were used for. Paleoenvironmental information will be obtained using multiple methodologies. Limb element ecomorphic analyses and isotopic analysis of carbonates will provide information on habitat structure. Ecomorphic analysis of mandibles and analysis of carbon isotopes from enamel will provide paleodietary information. Oxygen isotopes in tooth enamel will constrain paleotemperatures and the degree of seasonality during Kanjera Fm (S) deposition. Cementum analysis will be used to assess antelope season of death. Documentation of hominid utilization of open habitats at Kanjera may influence views of early hominid capabilities, including their ability to compete with large carnivores. This project should also contribute to the on-going debate over faunal acquisition strategies, by providing a test of whether small mammals were hunted. As the sample of medium and larger sized mammals increases, it may be possible to assess the timing of access to larger carcasses and thus whether hominids were passively or actively scavenging them. Our attempts to measure the intensity of seasonality through the sequence, as well as the influence of seasonality on hominid foraging for animal tissue, have not been conducted on this scale before and may provide valuable information on the motivation and frequency of Oldowan carnivory.