Medical News Tool-use became widespread 10,000 years earlier than we thought
3 June 2019
A large stone tool from different angles recovered from sediments in the Ledi-Geraru region of EthiopiaDavid Braun
By Michael MarshallOur hominin ancestors had started making stone tools on a regular basis around 2.61 million years ago – 10,000 years earlier than thought. The find hints that early humans invented stone tool manufacture several times.
David Braun of the George Washington University in Washington, DC and his colleagues reached the conclusion after discovering a collection of ancient tools at Ledi-Geraru in Ethiopia.
They were found just 5 kilometres from a second site where the oldest known fossil of our genus Homo, a jawbone from 2.8 million years ago, was discovered in 2013. “We think it makes the most sense that early Homo made those stone tools,” says Braun. However, he says we cannot rule out the possibility that a more ape-like hominin like Australopithecus was responsible.
The style of the artefacts classifies them as Oldowan stone tools, which were widely used by hominins over the next million years. Previously, the oldest known examples were 2.6-million-year-old tools from Gona, Ethiopia. Those from Ledi-Geraru are up to 2.61 million years old.
The team compared the Ledi-Geraru tools with other collections, including those from Gona, and found they were crude. The tools had “significantly lower numbers of actual pieces chipped off a cobble than we see in any other assemblage later on,” says Braun. The toolmakers may have been less skilled, or they may not have needed their tools to be particularly sharp yet.
But while the Ledi-Geraru tools are broadly similar to later Oldowan tools, they are drastically different to the oldest known stone tools, which were found at Lomekwi in Kenya and are 3.3 million years old. “Those have nothing to do whatsoever with what we see later on,” says Braun. “It’s possible there are multiple independent inventions of stone as a tool.”
Braun points out that some chimpanzees and monkeys regularly use stone tools. They are cruder than even the simplest Oldowan tools: chimps use blunt stones to smash things, whereas hominins used sharp rocks to cut. But the tendency is there.
The trouble is, that still leaves a gap of several million years between the common ancestor we share with chimps – which probably lived at least 7 million years ago and may well have used tools, including stone ones – and the first evidence of stone tool use in the hominin fossil record.
Braun suspects that we just haven’t found the older hominin tools yet. “Watching modern primates, you realise there’s probably no way that a large primate existed that wasn’t using tools,” he says. “I’m almost positive that early hominins were using tools at some point.” It may be that they only used tools made of wood and other materials, which have either perished or been overlooked.
Journal reference: PNAS, DOI: 10.1073/pnas.1820177116
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