Long-term behavioral adaptation of Oldowan toolmakers to resource-constrained environments at 2.3 Ma in the Lower Omo Valley (Ethiopia)

The long stratigraphic sequence of the Shungura Formation in the Lower Omo Valley documents 3 million years of hominin evolution, which, when combined with detailed paleo-depositional environmental data, provide a unique window onto the complex interactions between hominin landscape use and the development of stone tool mediated behaviors. It remains to be seen whether this behavior was related to a unique brief occupation event or the expression of an emerging long-term tradition. The hominins, Paranthropus aethiopicus and/or early member of the genus Homo , who occupied the Lower Omo Valley developed tool assisted behaviors from ~ 2.3 Ma in the stable riverine environments of the ancestral Omo River. This new technological behavior is concomitant in the Shungura Formation with the emergent ability of the toolmakers to deal with an environment poor in lithic resources. Here we report on the newly investigated site complex of OMO 79, which produced the first evidence for multiple phases of hominin settlement dedicated to non-ephemeral mixed activities. The development of this long-lasting techno-economic tradition could relate to a more generalized cognitive tipping point around 2.3 Ma marked by hominin increased capacities in resource processing.