This is a chopping tool / core from the lower Omo Valley in Ethiopia made from a quartz pebble (maximal diameter: 7 cm).
All studies from this location, published so far, point out that the early lithic artifacts, found in situ, are mainly flakes, made from quartz pebbles, similar to the example shown here, in an overwhelming majority of cases.
Pioneering research in the Lower Omo Valley was early initiated by Arambourg in 1933, and was continued by the International Omo Research Expedition between 1967 and 1976. These expeditions have produced one of the best-documented bio-environmental and chronostratigraphic Plio-Pleistocene records for the study of human and faunal evolution. Fortunately, the transdisciplinary Omo Group Research Expedition project is continuing.
Beginning with the 1970ies, very old lithic ensembles (“Oldowan”) were found in the Omo area. These findings placed the first appearance of stone tools prior to 2 Ma, some hundreds of thousands of years before those found at Olduvai Bed I, which until then were thought to be the oldest human artifacts anywhere.
The Shungura Formation in the Lower Omo Valley is currently the most complete sequence of sediments from the Plio-Pleistocene in Africa, dated from 3.6 Ma and ca. 1 Ma. Within the Omo Group, all early documented archaeological material comes from the Shungura Formation, (Member F deposits) dating from 2,32 Ma to 2,23 Ma.
While the discovery in the late 1970s of artefacts dated to ca. 2,6 Ma in the Hadar Formation demonstrated that the Omo lithic record is not the oldest-known lithic industry, it still represents an exceptional cultural heritage for assessing Early Pleistocene hominin behaviors. Nowadays we have several industries from the time horizon between 2,4-2,3 Ma (Gona, Hadar, Lokalalei and Kanjera) which are far from being techno-typological uniform.
The earliest Omo assemblages share a number of features with Gona, Hadar, Lokalalei and Kanjera and indicate the mastery of basic principles of stone knapping by our ancestors. With regard to assemblage composition, all these sites show similar percentages in which cores and flakes predominate, standardized forms are absent and retouched tools are not abundant.
Recurrent reduction of the same exploitation surfaces of cores is well attested, although there is substantial inter-assemblage variation regarding the use of unifacial, bifacial and multifacial methods. Core striking platforms are usually unprepared and rejuvenation products aimed to reactive flaking, although some- times documented (e.g. Lokalalei 2C), are not abundant; once knapping surfaces lose the necessary convexities, cores are discarded.
Raw material selectivity has been reported in most of the early sites , and it is likely that raw material factors played a major role in the length of reduction sequences; the quality, large size and abundance of cobbles in areas such as Gona , West Turkana and Hadar could have facilitated long sequences of core exploitation, whereas the smaller size of raw materials available in Omo and Kanjera conditioned the number of flaking series.
In sum, even the the earliest assemblages show a well- reasoned technological process which began with the preferential selection of suitable raw materials, continued with an understanding of the volumetric concepts required to exploit such raw materials and a successful application of that know-how in the reduction of cores, followed by an optimal production of flakes.
Until recently there was general agreement in positioning the earliest Oldowan evidence at ca. 2,6 Ma, hypothetically related to climatic changes, the living of our ancestors in savannah grassland environments, new hominin species (Homo sp.) and dietary shifts.
Nonetheless, the discovery of cut-marked fossils in Dikika that could be older than 3, 39 Ma and discovery of the earliest known stone tools at Lomekwi 3 (LOM3) from West Turkana, Kenya, dated to 3, 3 Ma, raises new questions about the mode and tempo of key adaptations in the hominin lineage.
If we still define Homo as stone tool making creature, it must have existed earlier that currently substantiated by the Paleoanthropological record. Anyhow, fossils dating to before 2, 8 Ma have not yet been found.
Alternatively we could say goodby to the “Homo the toolmaker” -paradigm and attribute the first stone artifacts from LOM3 to an earlier hominin like Australopithecus or even to an extinct large ape.