Olduvai Gorge, Tanzania, preserves an almost unprecedented record of early hominid biobehavioral evolution. As such, it provides a unique opportunity to document spatio-temporal variability in hominid behavior. New taphonomic data reveal that hominids played little or no role in the formation of the faunal assemblages from many of the sites excavated by Mary Leakey from Beds I and II. In fact, the faunas from only two sites, FLK 22 from Bed I and BK from Bed II, can be considered as largely the result of hominid subsistence activities. This finding has important implications for interpretations of the Olduvai lithics and for patterns of hominid subsistence in the paleo-Olduvai basin. Taphonomic proxies of competition also suggest that hominids concentrated their stone-tool-using activities in lower competition settings during Bed I times, while higher competition settings were exploited in greater frequency during Bed II times. The pattern that emerges is one of variability in site use by Plio-Pleistocene hominids in the Olduvai basin.

This paper describes a sinuous strip of outcrops that lies towards the top of the Koobi Fora Formation in northern Kenya and a research project established to investigate what this locality can reveal about the empirical structure of the early Pleistocene archaeological record and the behavioral information that can be generated from it. This is a logical pre-requisite to any attempt to reconstruct the behavior of early African Homo erectus (or indeed, any other debris-generating human ancestor). The main purpose of this paper, however, is to summarize the results of the first round of field research at FxJj43 and to consider their implications for future investigations.

From its initial appearance at ~1.7 Ma, the Acheulean was prevalent through a vast chronological span of hominin behavioural evolution that lasted nearly 1.5 million years. The origins and production patterns of large bifacial cutting tools ('LCTs') e the marker of the Acheulean techno-complex e and the systematic changes in this behaviour through time are gaining increasing interest in paleoan-thropology. Here we provide a synthesis of early Acheulean LCT variation in a landscape context by analysing assemblages from four different quasi-contemporaneous (~1.4 Ma) sites from the Koobi Fora Formation. We characterize this variation using both 3D geometric morphometric and descriptive approaches. The expansive lateral exposures of fluvial and lacustrine sediments, as well as the associated tephrostratigraphy of the Koobi Fora Formation provide the landscape context that enables these comparative analyses. Our study demonstrates that when multiple contemporaneous early Acheulean localities are analysed together, a broader picture of LCT variability is elucidated. Four sites at Koobi Fora appear to represent a single system of lithic economy, characterized by a discrete tra-jectory of changes in LCT size and shape. These sites have ranges of LCT forms which appear to represent different but overlapping stages on a single reduction trajectory. Certain sites exhibit the full reduction trajectory while others exhibit only fragments of this trajectory. Other inter-site lithic proxies further complement these patterns in LCT variability. We explore patterns of site function, mobility and hominin landscape use, all of which may be suggestive of a depth of planning in early Acheulean hominins wherein technological activities were undertaken in substantial anticipation of future needs.