London: Scientists claim to have discovered the world`s earliest sophisticated stone tools that are 1.76 million years old, suggesting that ancient humans were using advanced tool-making methods about 300,000 years earlier than previously thought.
The teardrop-shaped hand-axes that would have been used for a range of tasks from chopping wood to cutting up meat were unearthed near Lake Turkana in northwest Kenya.
They would have been so useful that scientists described them as the "Swiss army knife" of the Stone Age, the BBC reported.
Researchers believe that the tools were probably made by the human ancestor Homo erectus, tall and slender early humans who appeared about 2 million years ago and disappeared about 70,000 years ago.
Palaeolithic stone tools can be grouped into a number of different styles. The type found at Kokiselei archaeological site is called Acheulian technology.
These are larger and heavier than the pebble-choppers (Oldowan technology) that were used previously and which are associated with a more primitive human known as Homo habilis.
The Acheulian hand-axes also have distinctive chiseled edges and manufacturing them would have required forethought in design and the careful selection of rocks.
The study reported in Nature shows the tools were in use some 350,000 years earlier than all previous Acheulian finds.
This dating places them closer to the origins of Homo erectus, and suggests the Acheulian was the proprietary technology of this specific human species, said lead author Dr Christopher Lepre from Rutgers University in the US.
"Our finding does suggest that the Acheulian was indeed invented nouveau by Homo erectus," he said.
"There probably wasn`t that period of borrowing from Homo habilis, meaning that once Homo erectus had originated, they invented this new tool technology -- the Acheulian hand-axe," Dr Lepre added.
If Homo erectus originated in Africa and then spread out across Asia, the puzzle, the researchers said, is why the species did not take the more advanced Acheulian capability
with it immediately -- it`s hundreds of thousands of years before the technology became widespread elsewhere in the world.
"If Homo erectus has the technology and has evolved the behaviour this early, why not see it right away (out of Africa)?" pondered Rhonda Quinn from Rutgers University.
"Why didn`t this advanced technology aid the dispersal, to tap into new environments? she said.