The earliest evidence of stone tools which were used as instruments has been found at an archaeological site in Ethiopia.
Previously, the oldest evidence for systematic stone tool production and use was 2.58 to 2.55 million years ago.
However, the new find shows that the origins of stone tool production are not only older than 2.58 million years, but also suggest that stone tools may have been invented many times by different groups at roughly the same time.
Early humans are believed to have created tools by shearing flakes of stone from larger rocks to make weapons, hunting and scrapping animals and chopping wood.
The production technology suggests our primitive ancestors were much more intelligent than previously believed.
The tools were dug up at a site known as Bokol Dora 1 or BD 1 in the Afar region of north-eastern Ethiopia.
It is near where the oldest fossilised jaw bone of our genus Homo dating to about 2.78 million years ago was found five years ago, some 200,000 years before the then oldest flaked stone tools.
The team of from has been working ever since to find out if there is a connection with the origins of systematic stone tool manufacture.
Geologist Professor Christopher Campisano, of Arizona State University in the US, saw the sharp-edged stone tools sticking out of the sediments on a steep, eroded slope.
He said: ‘At first we found several artifacts lying on the surface, but we didn’t know what sediments they were coming from.
‘But when I peered over the edge of a small cliff, I saw rocks sticking out from the mudstone face.
‘I scaled up from the bottom using my rock hammer and found two nice stone tools starting to weather out.’
It took years to excavate through metres of rocks by hand before exposing an archaeological layer of animal bones and hundreds of small pieces of chipped stone.
The site records a wealth of information about how and when humans began to use stone tools.
Preservation of the artifacts comes from originally being buried close to a water source.
Archaeologist Vera Aldeias, of the University of Algarve in Portugal, said: ‘Looking at the sediments under a microscope, we could see the site was exposed only for a very short time.
‘These tools were dropped by early humans at the edge of a water source and then quickly buried.’
The animals found with these tools were similar to those found only a couple of miles away with the earliest Homo fossils.
Professor Kaye Reed, who studies the site’s ecology at Arizona State, said: ‘The early humans that made these stone tools lived in a totally different habitat than ‘Lucy’ did.’
‘Lucy is the nickname for an older species of hominin known as Australopithecus afarensis, which was discovered at Hadar about 20 miles from BD 1.
Professor Reed said: ‘The habitat changed from one of shrubland with occasional trees and riverine forests to open grasslands with few trees. Even the fossil giraffes were eating grass!’
Our technology and biology were intimately intertwined even as early as 2.6 million years ago.
Lead author Dr David Braun, an archaeologist with George Washington University in Washington DC, added: ‘Primate species throughout the world routinely use stone hammers to forage for new resources.
‘It seems very possible throughout Africa many different human ancestors found new ways of using stone artifacts to extract resources from their environment.
‘If our hypothesis is correct then we would expect to find some type of continuity in artifact form after 2.6 million years ago, but not prior to this time period. We need to find more sites.’
The work was published in the journal Proceedings of the National Academy of Sciences.