The Oldowan stones are believed to be the oldest known examples of stone tool industry in the world. Their development around 2-3 million years ago represents a significant moment in our evolutionary history as it demonstrates the first evidence of cultural behaviour. But while the stone tools themselves are well known among archaeologists and other researchers, their creators’ exact identity remains a mystery. Now, a new study has assessed the evidence to help narrow down the possible candidates.
The first examples of these tools were discovered at Olduvai Gorge in Tanzania in the 1930s, but others have been recovered from other locations in eastern, central, and southern Africa. The oldest comes from an archaeological site at Gona, in Ethiopia. The stones are generally characterized by hand-held cores that have sharp edges created when flakes were knapped off their surfaces. This leaves the stones with an edge that can be used for cutting, chopping, or scraping activities.
Given their significance, these tools are among the most well-known and most intensively researched lithic (stone) technologies and have been the subject of decades of research. However, the scientific community is still unsure as to who created them. Generally speaking, the stone tools have often been associated with a particular hominin, but the Oldowan assemblages are considered too varied to be linked to a single genus. In particular, sites in southern Africa and Algeria suggest that more than one hominin genus may have produced the Oldowan tools found there.
Stone “choppers” found in Ethiopia dating back to 1.7 million years ago.
Image credit: Didier Descouens
Before an early Homo genius was suspected, researchers believed Paranthropus boisei, a species of australopithecine from the Early Pleistocene era were the most likely manufacturers. But now it is accepted that someone like Homo habilis – the “handy man” – may have created them. This genus of extinct hominids is known for their larger brains and more dexterous hands, which made them a more likely candidate than the more “primitive” Paranthropus. However, more recent excavations have identified evidence of Oldowan tools that push back the known age of their creation to around 3.3 millions years ago, indicating that the tool-making behaviour may well have been present in species that predate the genus Homo.
As such, Paranthropus boisei is a contender again, alone with species like Homo rudolfensis, Homo erectus, Australopithecus garhi, and Australopithecus africanus, among others. There are even some who maintain that both Homo species and Paranthropus may have made and used the tools at different sites.
It’s a complex mess of a problem, but new research has helped narrow down the options. In their study, an international team of researchers examined the long-standing debate by reviewing the hominin taxa that overlap with the Oldowan tools across time. Using a process known as optimal linear estimation modeling, a statistical technique used to assess the potential relationship between variables, the team was able to estimate when the first and last appearances of each candidate species and the Oldowan tools.
The model indicated that the Oldowan technology first appeared around 3.25 million years ago and lasted until 1.6 or 1.2 million years ago, which makes it the longest-lived human cultural tradition ever known. Moreover, the results showed that the emergency of certain Homo species and the extinction of the earlier species, like Australopithecus coincided with the first and last appearances of the stone tools.
“Australopithecus afarensis is also excluded from having made Oldowan tools throughout its entire temporal range, as there is currently no temporal overlap between known Au. afarensis fossils and Oldowan sites,” the team write in their paper.
The authors also suggest that the evidence for Australopithecus africanus and Paranthropus robustus, is also too limited for their temporal overlap with these technologies to be considered the main candidates.
“This does not preclude either Au. africanus or P. robustus from having produced Oldowan tools—there is clear temporal overlap in the known fossil sites for each taxon and the Oldowan, with room for substantial date-range error—but it does mean the resolution of our understanding is limited and greater weight should be given to alternative sources of tool-use evidence.”
Ultimately, the team concluded that no one species or genus was responsible for creating the stones, given their vast distribution across different hominin fossil sites. It is likely, they argue, that a mix of hominin species as well as Paranthropus boisei made them, a conclusion other studies have also come to.
“Potentially, cultural information was transferred between early Homo and P. boisei, whereby P. boisei acquired Oldowan capabilities, but this need not be direct social learning (imitation, emulation or teaching), for other possibilities exist (e.g., reverse engineering, cultural convergence),” the team explain.
It is possible that, when Homo species, like Homo Erectus, developed Acheulean tools – more sophisticated stone tools that included axe and cleaving implements – P. boisei continued making and using the Oldowan tools.
The paper is published in the Journal of Anthropological Archaeology.
Source Link: We're A Step Closer To Knowing Who Made The Earliest Known Stone Tools
