Late Pliocene Oldowan excavations at Kanjera South, Kenya. (Special section).

Late Pliocene Oldowan excavations at Kanjera South, Kenya. (Special section). The appearance of Oldowan sites c. 2.5 million years ago signalsone of the most important adaptive shifts in human evolution. Largemammal butchery, stone artefact manufacture and novel transport anddiscard behaviours led to the accumulation of the first recognizedarchaeological debris. Although the earliest instances of thesebehaviours are 2.5 million years ago, most of what we know about Oldowanpalaeoecology paleoecology, palaeoecologythe branch of ecology that studies the relationship of ancient plants and animals to their environments. — paleoecologic, palaeoecologic, paleoecological, palaeoecological, adj. and behaviour is derived from localities more than half amillion years younger, particularly c. 1.8 million-year-old sites fromBed I Olduvai Gorge, Tanzania (Potts 1988). Sites from Kanjera South,Homa Peninsula, southwestern Kenya, yield dense concentrations ofartefacts in association with the oldest (c. 2.2 million years)substantial sample of archaeological fauna known thus far from Africa.This study is the first to use a wide range of traditional andinnovative techniques to investigate Oldowan hominin behaviour and siteformation processes before 2 million years ago. The sedimentary sequence at Kanjera South is approximately 12 mthick (FIGURE 1). It consists of six beds, from oldest to youngest KS-1to KS-6 (Behrensmeyer et al. 1995; Ditchfield et al. 1999). The basalKS-1 to KS-3 sands and silts, the target layers of our excavations, weredeposited by low aspect channels at the margin of a small lake or playa.They exhibit weak to moderate pedogenesis. KS-4 clays were depositedduring a lake transgression while KS-5 and KS-6 sands and silts reflecta return to fluvial flu��vi��al?adj.1. Of, relating to, or inhabiting a river or stream.2. Produced by the action of a river or stream.[Middle English, from Latin deposition. [FIGURE 1 OMITTED] Excavations in 1996, 1997 and 2000 uncovered rich concentrations ofartefacts and fossils in KS-1 to KS-3. Two large excavations(Excavations 1 and 2; 100 sq. m and 15 sq. m, respectively) and threesmaller ones (Excavations 5-7, each 4 sq. m) were placed along a 70-mtransect of outcrop (Plummer et al. 1999). While artefacts and faunawere recovered in each of the excavations, object density was highest inExcavations 1 and 2, suggesting that the concentrations in these siteswere above average background densities. At Excavation 1, artefacts werefound in association with a taxonomically diverse faunal assemblage inKS-1 and KS-2 (FIGURE 2-4). At Excavation 2, Bed KS-3 yielded a completehippopotamus hippopotamus,herbivorous, river-living mammal of tropical Africa. The large hippopotamus, Hippopotamus amphibius, has a short-legged, broad body with a tough gray or brown hide. pelvis with five articulated vertebrae VertebraeBones in the cervical, thoracic, and lumbar regions of the body that make up the vertebral column. Vertebrae have a central foramen (hole), and their superposition makes up the vertebral canal that encloses the spinal cord. , a canine and tworibs in tight spatial association with five flakes, possiblyrepresenting a hippopotamus butchery site. Taxonomically diverse faunalsamples with associated artefacts were found below the hippopotamusbones in KS-1 and KS-2. [FIGURES 2-4 OMITTED] Stable carbon isotopic values from palaeosol carbonates from thearchaeological layers are more strongly positive than any Miocene orPliocene East African samples, suggesting that hominin activities atKanjera South were carried out in an open (>75% [C.sub.4] grass)setting (Plummer et al. 1999). A palaeocommunity incorporating largetracts of secondary grassland (dry grasslands where factors such asgrazing impede woody growth) is suggested by high proportions ofalcelaphine antelopes and equids in the archeological fauna. Incontrast, faunal and isotopic evidence suggest that the earliestarcheological occurrences at Bed I Olduvai formed under much more woodedconditions (Plummer & Bishop 1994; Sikes 1994). Hominin marrowprocessing and carnivore damage to bone, as well as several artefact andfossil conjoins, have been identified during preliminary laboratoryanalysis of the Excavation I fauna. Small mammal hunting is suggested bythe relatively high proportion of size class 1 and 2 mammals, many ofwhich were immature (FIGURE 4). This contrasts with the Bed I Olduvaisites, where medium (size class 3) mammals were the most common and arethought to have been obtained largely through scavenging. Hominins atKanjera South utilized a wider variety of lithic lith��ic?1?adj.Consisting of or relating to stone or rock.Adj. 1. lithic - of or containing lithium2. lithic - relating to or composed of stone; "lithic sandstone" raw materials thanfound at most Oldowan sites, some of which (chert chert:see flint. , quartz, quartzite)must have been transported from outside the immediate vicinity of thedeposits since they are not present in the local clast population. On-going research at Kanjera will refine our understanding of thepalaeoenvironmental setting, rigorously test the hypothesis of smallmammal hunting, assess hominin utilization and curation of artefacts byraw material type and synthesize this information with researchelsewhere to reconstruct more completely the behavioural ecology of thefirst archaeological hominins. Acknowledgements. We respectfully thank the Office of thePresident, Republic of Kenya, and M.G. Leakey and G. Abungu of theNational Museums of Kenya for permission and support in conducting theKanjera field and laboratory studies. The Kanjera excavations wereconducted through the cooperative agreement between the National Museumsof Kenya and the Smithsonian Institution. Funding from the L.S.B. LeakeyFoundation, the National Geographic Society, the National ScienceFoundation and the Wenner-Gren Foundation is gratefully acknowledged. References BEHRENSMEYER, A.K., R.B. POTTS, T. PLUMMER, L. TAUXE, N. OPDYKE& T. JORSTAD. 1995. The Pleistocene locality of Kanjera, WesternKenya: stratigraphy, chronology and paleoenvironments, Journal of HumanEvolution 29: 24774. DITCHFIELD, P., J. HICKS, T. PLUMMER, L.C. BISHOP & R.B. POTTS.1999. Current research on the late Pliocene and Pleistocene depositsnorth of Homa Mountain, southwestern Kenya, Journal of Human Evolution36: 123-50. PLUMMER, T. & L.C. BISHOP. 1994. Hominid paleoecology pa��le��o��e��col��o��gyn.The branch of ecology that deals with the interaction between ancient organisms and their environment. atOlduvai Gorge, Tanzania as indicated by antelope remains, Journal ofHuman Evolution 27: 47-75. PLUMMER, T., L.C. BISHOP, P. DITCHFIELD & J. HICKS. 1999.Research on Late Pliocene Oldowan Sites at Kanjera South, Kenya, Journalof Human Evolution 36: 151-70. POTTS, R.B. 1988. Early hominid activities at Olduvai. New York(NY): Aldine de Gruyter. SIKES, N. 1994. Early hominid habitat preferences in East Africa:paleosol pa��le��o��sol?n.A soil horizon from the geologic past, usually buried beneath other rocks or recent soil horizons.[New Latin : paleo- + Latin solum, soil. carbon isotopic evidence, Journal of Human Evolution 27: 25-45. RICHARD POTTS, Plummer, Department of Anthropology, Queens College,CUNY CUNY City University of New York , Flushing, NY 11367, USA. Thomas_plummer@qc.edu Ferraro, Departmentof Anthropology, UCLA UCLA University of California at Los AngelesUCLA University Center for Learning Assistance (Illinois State University)UCLA University of Carrollton, TX and Lower Addison, TX , Los Angeles, CA 90095, USA. jferraro@ucla.eduDitchfield, Department of Geology, University of Bristol, Bristol BS81RJ, England. p.ditchfield@bristol.ac.uk Bishop, Biological & EarthSciences, Liverpool John Moores University Originally founded as a small mechanics institution (Liverpool Mechanics' School of Arts) in 1825, the institution grew over the centuries by converging and amalgamating with different colleges and eventually became the Liverpool Polytechnic. , Liverpool L3 3AF, England.L.C.Bishop@livjm.ac.uk Ports, Human Origins Program, Department ofAnthropology, Smithsonian Institution, Washington DC 20560, USA. Potts.Rick@NMNH.SI.EDU