A recently published study reveals that stone tools found almost by accident on the shore of Lake Turkana, in Kenya, in 2011, are by far the oldest known.
     The discovery challenges the notion that the things that made humans unique among primates all evolved around the same time, and suggests that other, more distant relatives knew how to fashion their own tools out of stone at least 3.3 million years ago.
     Lead study author Sonia Harmand, of Stony Brook University and the Universite Paris Ouest Nanterre, says: "Our discovery instantly pushed back the beginning of the archaeological record by 700,000 years, or over a quarter of humanity's previously known material cultural history."
     Many primates use items like sticks as tools, and other species even use rocks as tools, but actually making a tool was thought to be something exclusive to members of the genus Homo, which is believed to have appeared roughly 2.8 million years ago, and includes modern humans. The traditional view was that stone tool making, along with other key human traits such as language and meat-eating, evolved at that time.
     It remains unknown what species made these stone tools. They could have been created by an undiscovered extinct human species, or by Australopithecus, which is currently the leading contender for the ancestor of the human lineage, or by Kenyanthropus, a 3.3-million-year-old skull of which was discovered in 1999 about 1 kilometre from where the tools were later found.
     Analysis of carbon isotopes in the soil and animal fossils at the site revealed a partially wooded, shrubby palaeo-environment.
     Replicating the toolmaking process, the researchers conclude the techniques used may represent a stage between the pounding used by earlier hominins and the knapping of later toolmakers. This discovery also has implications for understanding the evolution of the human brain.
     Scientists are now looking at the surfaces and edges of the tools and studying the sediment in which they were found to try to reconstruct how they were used.

Edited from LiveScience (20 May 2015), CNBC (21 May 2015)