Stone tools unearthed in Kenya's Lake Turkana date back 3.3 million years ago and are now the oldest such artifacts ever discovered.
According to BBC News, the discovery pushes back the first known appearance of stone tools by about 700,000 years. A team of scientists detailed their findings in a study published in the journal Nature.
"The whole site's surprising, it just rewrites the book on a lot of things that we thought were true," study co-author Chris Lepre, a geologist at the Lamont-Doherty Earth Observatory and Rutgers University, said in a press release.
Dubbed Lomekwi 3, the first set of tools was discovered at the site in 2011 and, through the end of the 2012, archaeologists had found 149 in all.
"The very largest one we have weighs 15kg, which is massive," study co-author Nick Taylor, of the National Centre of Scientific Research (CNRS) in France and the University of Leiden in the Netherlands, told BBC News. "On this piece, it doesn't show the signs of actually having been flaked to produce other artifacts... rather, it was probably used as an anvil.
"It probably rested in the soil and the other cobbles brought to the site, which were intended to be smashed apart to make tools, were struck against this large anvil."
The researchers were not able to determine who crafted these tools, as they predated Homo habilis, the species believed to have first used such instruments.
"There are a number of possible candidates at present," Taylor said. "There was a hominin called Kenyanthropus platyops, which has been found very close to where the Lomekwi 3 tools are being excavated. And that hominin was around at the time the tools were being made.
"More widely in the East African region there is another hominin, Australopithecus afarensis, which is famously known from the fossil Lucy, which is another candidate."
