AbstractThe Acheulean technological tradition, characterized by a large (>10 cm) flake-based component, represents a significant technological advance over the Oldowan. Although stone tool assemblages attributed to the Acheulean have been reported from as early as circa 1.6–1.75 Ma, the characteristics of these earliest occurrences and comparisons with later assemblages have not been reported in detail. Here, we provide a newly established chronometric calibration for the Acheulean assemblages of the Konso Formation, southern Ethiopia, which span the time period ∼1.75 to <1.0 Ma. The earliest Konso Acheulean is chronologically indistinguishable from the assemblage recently published as the world’s earliest with an age of ∼1.75 Ma at Kokiselei, west of Lake Turkana, Kenya. This Konso assemblage is characterized by a combination of large picks and crude bifaces/unifaces made predominantly on large flake blanks. An increase in the number of flake scars was observed within the Konso Formation handaxe assemblages through time, but this was less so with picks. The Konso evidence suggests that both picks and handaxes were essential components of the Acheulean from its initial stages and that the two probably differed in function. The temporal refinement seen, especially in the handaxe forms at Konso, implies enhanced function through time, perhaps in processing carcasses with long and stable cutting edges. The documentation of the earliest Acheulean at ∼1.75 Ma in both northern Kenya and southern Ethiopia suggests that behavioral novelties were being established in a regional scale at that time, paralleling the emergence of Homo erectus-like hominid morphology.
Of course that there are hundreds of thousands of years in between and of course that the peculiar orography of the Rift Valley is susceptible of offering archaeological findings from old much more easily than other areas but still…
Update: much more than just the edges but a whole technological paradigm change:
I was not really appreciating the whole extent of the technological revolution implicit in these changes. I just took note (reading too fast, too many things to do) of the edge refinement but Va_Highlander has correctly called my attention on that it was a much more ample and complex change in the whole technology of stone flaking and not just the edges, maybe even a whole jump in our mental capacities:
In contradistinction to the >1.2-Ma assemblages, the younger ∼0.85-Ma Konso Acheulean is characterized by considerably refined handaxes. Some of these handaxes are refined to the extent that they would qualify as approaching “three-dimensional symmetry” (i.e., symmetric not only in plan view but also in cross-section form) (Fig. 4 and Fig. S2). Some suggest that manufacturing 3D symmetric tools is possible only with advanced mental imaging capacities and that such tools might have emerged in association with advanced spatial and navigational cognition, perhaps related to an enhanced mode of hunting adaptation. It has been pointed out that purposeful thinning of large bifacial tools is technologically difficult, even in modern human ethnographic settings. In modern humans, acquisition and transmission of such skills occur within a complex social context that enables sustained motivation during long-term (>5 y) practice and learning.
In light of the above information, it is of interest that our metric analysis shows that there may be a fundamental difference between the handaxe technologies of >1.2 and ∼0.85 Ma. Whereas refinement of handaxe shape did occur from ∼1.6 to ∼1.2 Ma, this refinement did not result in tool thinning and advanced 3D symmetry.