The Environmental Context of Oldowan Hominin Activities at Kanjera South, Kenya

The earliest archaeological traces and two new hominin genera (Homo and Paranthropus) appear in the late Pliocene of Africa. These first appearances may reflect novel hominin adaptive responses to shifting resource bases over geological time and/or an increasingly seasonal distribution of food over the annual cycle. Whereas regional environmental change has been documented during the Plio-Pleistocene of East Africa, it is difficult to resolve relative proportions of specific habitats at a given place and time, how these may have changed over time, and the explicit nature of particular habitats. Detailed reconstructions of paleohabitats based on paleontological, geological and geochemical evidence are necessary in order to better understand the interplay between environmental change and hominin biological and behavioral evolution. Reconstruction of the habitats in which archaeological sites were formed provides a window on habitat utilization by early Homo, independent of inferred hominin adaptations to specific environmental settings based on hominin morphology or the postmortem distribution of hominin fossils. Here we report on the paleoenvironmental setting of the ca. 2.0 Ma archaeological occurrences at Kanjera, southwestern Kenya. Sedimentological analysis indicates that the site was formed in an alluvial fan, probably near the margin of a lake. Isotopic analysis of pedogenic carbonates indicates that the site complex was formed in an open habitat. Bovid dietary category and taxonomic representation demonstrates that a preponderance of animals grazed and preferred open habitats. Site formation occurred in a grassland-dominated ecosystem, rather than an isolated patch of grassy vegetation within a more wooded setting.