The appearance of the Acheulean is one of the hallmarks of human evolution. It represents the emergence of a complex behavior, expressed in the recurrent manufacture of large-sized tools, with standardized forms, implying more advance forethought and planning by hominins than those required by the precedent Oldowan technology. The earliest known evidence of this technology dates back to c. 1.7 Ma. and is limited to two sites (Kokiselei [Kenya] and Konso [Ethiopia]), both of which lack functionally-associated fauna. The functionality of these earliest Acheulean assemblages remains unknown. Here we present the discovery of another early Acheulean site also dating to c. 1.7 Ma from Olduvai Gorge. This site provides evidence of the earliest steps in developing the Acheulean technology and is the oldest Acheulean site in which stone tools occur spatially and functionally associated with the exploitation of fauna. Simple and elaborate large-cutting tools (LCT) and bifacial handaxes co-exist at FLK West, showing that complex cognition was present from the earliest stages of the Acheulean. Here we provide a detailed technological study and evidence of the use of these tools on the butchery and consumption of fauna, probably by early Homo erectus sensu lato.

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In this paper, we present the results of new archaeological and geological research carried out in SHK Extension, a new site excavatedwithin the SHK fluvial complex (Bed II, Olduvai Gorge). The paper describes the stratigraphy of the site and its correlation with our excavation in SHK Main Site, showing that overbank archaeological accumulations in both areas are synchronous and form part of the same fluvial palaeo-landscape. On the basis of the archaeostratigraphical analysis performed, mainly geared towards defining high-resolution chrono-stratigraphical frameworks within the deposit, we report the results of a technological study of the lithic collection sorted by archaeo-units, an assessment of the integrity of the main accumulation and an exhaustive lithic refitting programme. The archaeological sequence at SHK Extension, consisting of three archaeo-units, preserves a high-density patch of lithics and fossil bones (Level B2), on an overbank setting, isochronous with the SHK Main site. The high percentage of small lithic remains and bones, large number of fresh archaeological materials, and the identification of several refit sets support the integrity of the anthropogenic accumulation documented in Level B2. The main technological trait of the lithic assemblage from this level is the preservation of a qualitatively significant sample of large flakes and LCTs. The technological behaviours observed in SHKE, in the frameworkof the SHK complex, confirm that the complex web of inter-assemblage variability during Bed II times operated also in very close fractions of the same palaeo-landscape. This reinforces the idea that subtle functional parameters must be taken into account in our current assessment of the Developed Oldowan/Acheulean interface.Fernando Diez-Mart ın (fernando.diez.martin@uva.es),

The Acheulean materials documented in FLK West dated c. 1.7 Ma. are the focus of the present work. An original techno-functional approach is applied here to analyze the origin of Acheulean tools. According to the results, these tools were employed in different functional contexts in which tasks of different durations that transformed resources with different resistances were carried out. The exploitation of large and resistant resources suggests that the economic mechanism governing the manufacture of these tools was an increase in the demand of the work load. The decision processes underlying the production of these tools have thus an evident functional motivation. However, the presence of a refined handaxe in the studied sample indicates that the design form and production principles of handaxe manufacture were the result of an abrupt emergence rather than a long gradual development. The integration of mechanical and ergonomic investigation in our research has been crucial to explain how a core-and-flake industry gave way to a technology based on the production of large and heavy shaped tools.

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