3.3-million-year-old stone tools discovery in Kenya

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3.3-Million-Year-Old Stone Tools Found in Kenya

23 May 2015

Archaeologists find stone tools used by early human ancestors in Kenya that predate the oldest known tools found in Ethiopia by some 700,000 years.

From daily The Guardian in Britain:

Stone tool discovery pushes back dawn of culture by 700,000 years

Finding overturns idea that tool-making ability was unique to our own ancestors and is hailed as a “new beginning to the known archaeological record”

Hannah Devlin, science correspondent

Wednesday 20 May 2015 18.00 BST

The oldest known stone tools, dating to long before the emergence of modern humans, have been discovered in Africa.

The roughly-hewn stones, which are around 3.3 million years old, have been hailed by scientists as a “new beginning to the known archaeological record” and push back the dawn of culture by 700,000 years.

The discovery overturns the mainstream view that the ability to make stone tools was unique to our own ancestors and that it was one of a handful of traits that made early humans so special.

The new artefacts, found in Kenya’s Turkana basin, suggest that a variety [of] ancient apes were making similar advances in parallel across the African continent.

“It just rewrites the book on a lot of things that we thought were true,” said Chris Lepre, a geologist at the Lamont-Doherty Earth Observatory and Rutgers University, who precisely dated the tools.

The Homo genus, from which modern humans descend, only emerged around 2.5 million years ago, when forests gave way to open grassland environments in Africa. Until now, it was widely assumed that environmental changes around this time triggered the shift towards a bipedal hunter-gatherer life style.

Jason Lewis, of Stony Brook University in New York and a co-author, said: “The idea was that our lineage alone took the cognitive leap of hitting stones together to strike off sharp flakes and that this was the foundation of our evolutionary success. This discovery challenges the idea that the main characters that make us human, such as making stone tools, eating more meat, maybe using language, all evolved at once in a punctuated way, near the origins of the genus Homo.”

The question of what, or whom, might have made the tools remains a mystery, but fossils from around the same period found at the site provide some clues.

The skull of a 3.3-million-year-old hominin, Kenyanthropus platytops [sic; K. platyops] , was found in 1999 about a kilometre from the tool site and a skull fragment and tooth from the same species were found just a few hundred metres away.

Other species from the same era include Australopithecus afarensis, which the famous Lucy fossil belongs to.

Professor Fred Spoor, a palaeontologist at University College London and part of the team that discovered K. platytops [sic; platyops], said the tools were “a very important find”. “Until now the thinking’s been that if you want to be part of this special club ‘Homo’, you need to be a tool-maker,” he said. “The period before three million years ago was seen as a rather boring period of evolution, but now we know there was stuff happening.”

Until now, hominins such as Australopithecus, from the earlier time period have been caricatured as “upright, bipedal chimpanzees that were just grazing the landscape with not much else going on,” he added.

To the untrained eye, the tools look unremarkable – barely distinguishable from ordinary rocks. But to scientists familiar with early humans, the hallmarks of tool-making were obvious. “I could immediately see the scars and features characteristic of a knapped stone,” said Sonia Harmand, of Stony Brook, who made the discovery.

Professor Spoor and others who have examined the collection of tools have been impressed by the quality of the evidence.

“This is a momentous and well-researched discovery,” said paleoanthropologist Bernard Wood of George Washington University, who was not involved in the study. “I have seen some of these artefacts in the flesh, and I am convinced they were fashioned deliberately.”

The collection of several dozen tools appears to have been made by two different techniques. In one case, a core stone was held on an anvil and hit from above with a hammer stone to chip off sharp flakes, which the scientists believe could have been used to slice meat and plants. Other stones appear to have been held in two hands and struck against the anvil, again producing slices of stone.

Although the end results appear primitive, they demonstrate a degree of mental sophistication that is unexpected for such early hominins. Modern chimpanzees use natural stones as “tools” to crack nuts, for instance, but they stop short of actively fashioning their own tools.

The researchers relied on a layer of volcanic ash below the tools, which matched ash elsewhere that had been dated to 3.3 million years ago, to set a “floor” on the site’s age. The date was then refined by analysing magnetic minerals at the site, which contain a record of the Earth’s periodically switching magnetic field.

The findings are published today in the journal Nature.