Scientists discovered the oldest stone tools known to science while working in the desert badlands of northwestern Kenya. These fascinating tools date back 3.3 million years, which is well before the advent of modern humans.
The makers of the tools are believed to have been some form of human ancestor, and push the oldest-known tools back 700,000 years, the Earth Institute at Columbia University. They also challenge the idea that our most direct ancestors were the first to start using simple tools, and could change the way we perceive the thinking ability of these ancient beings.
"[The tools] shed light on an unexpected and previously unknown period of hominin behavior and can tell us a lot about cognitive development in our ancestors that we can't understand from fossils alone," said lead author Sonia Harmand, of the Turkana Basin Institute at Stony Brook University and the Universite Paris Ouest Nanterre.
In the past, researchers thought the Homo species that led directly to modern Homo sapiens, were the first to create stone tools, but this finding suggests the credit should actually go to a much more distant cousin. The discovery of a skull from a hominin called Kenyanthropus platytops on the site suggests this group may have been the great innovators. Kenyanthropus predates the earliest known Homo species by about half a million years. The tools may have also been created by Australopithecus afarensis or an unknown type of Homo.
The ratio of argon isotopes in the volcanic ash below the tool site suggests the artifacts are around 3.3 million years old. The researchers also looked at magnetic minerals around where the tools were found to back up their findings; the Earth's magnetic field has reversed itself several times throughout history, and these changes are well-documented over the past several million years. These measurements came to the same conclusion as the isotope analysis.
"We essentially have a magnetic tape recorder that records the magnetic field ... the music of the outer core," Kent said.
In another surprising finding, the researchers noticed local carbon isotopes indicated the area was partially wooded and contained shrubs at the time that the tools were made. Many scientists believed tools were first created to cut meat, but the markings on the recently-discovered artifacts suggest they were actually used to break open nuts and tubers, or break logs to gain access to insects.
"Researchers have thought there must be some way of flaking stone that preceded the simplest tools known until now," said Richard Potts, director of the Human Origins Program at the Smithsonian's National Museum of Natural History, who was not involved in the research. "Harmand's team shows us just what this even simpler altering of rocks looked like before technology became a fundamental part of early human behavior."
The tools were described in a recent edition of the journal Nature.