2.9m-year-old stone tools found at Kenyan site

An international team of archaeologists – including researchers from La Trobe University – have found what’s likely to be the oldest examples of a stone-age innovation, in the form of a stone toolkit, as well as the oldest evidence of hominins consuming very large animals.

Researchers previously assumed that only the genus Homo, to which humans belong, was capable of making stone tools. However, along the shores of Lake Victoria in Kenya, Paranthropus (meaning beside man) fossils were discovered next to these stone tools at a time period when Homo is not present, opening up fascinating possibilities of another hominin species using tools.

New research published in Science reveals the stone tools were used hundreds of thousands of years earlier than previously thought, and over a larger geographic area.

Researcher at La Trobe University, and Head of The Australian Archaeomagnetism Laboratory, Professor Andy Herries completed the palaeomagnetic dating on the rocks found at the African site. This is a method that identifies magnetic changes and reversals in the Earth’s magnetic field fossilised in rocks to work out their age.

Professor Herries identified two magnetic reversals at Nyayanga with the Paranthropus fossils and stone tools lying in a layer just above one of these that dates to ~3 million years

“The magnetic minerals in layers in which the Paranthropus fossils and stone tools occur are pointing towards the north, as they do today, but just below this they are pointing in random directions that show the Earth’s magnetic field was going through a change from pointing south to pointing north,” said Professor Herries.

“When combined with other dating methods this suggests the fossils and stone tools date to just after three million years old, making them the oldest known of this species and industry.”

Professor Herries said the toolkit, known as ‘Oldowan’, was first found in the 1950s in 1.8 million year old layers at the famous Olduvai Gorge, also in association with Paranthropus, but the discovery of the early human species Homo habilis (Handy Man) soon after relegated Paranthropus to a non stone tool user.

“This discovery shows that the earliest Oldowan toolkit was more geographically widespread than previously known, and again centres Paranthropus as the potential originator of this industry, around a million years prior to the discoveries at Olduvai Gorge”.

Before this discovery the oldest known example of Oldowan tools were 2.6 million year-old tools unearthed in Ledi-Geraru, Ethiopia.

The Oldowan toolkit includes three types of stone tools: hammerstones, cores and flakes. Hammerstones can be used for hitting other rocks to create tools or for pounding other materials.

Through analysis of the wear patterns on the stone tools and animal bones discovered at Nyayanga, Kenya, the team behind this latest discovery shows that these stone tools were used by early human ancestors to process a wide range of materials and foods, including plants, meat and even bone marrow.

These stone toolmakers would have eaten everything raw, perhaps pounding the meat into something like a hippo tartare to make it easier to chew.

The site featured at least three individual hippos. Two of these incomplete skeletons included bones that showed signs of butchery.

Lead study author Professor Thomas W. Plummer, Queens College and research associate in the scientific team of the Smithsonian’s Human Origins Program, said it’s a very early example of the technology.

“It is one of the oldest if not the oldest example of Oldowan technology,” Plummer said.

“This shows the toolkit was more widely distributed at an earlier date than people realized, and that it was used to process a wide variety of plant and animal tissues. We don’t know for sure what the adaptive significance was but the variety of uses suggests it was important to these hominins.”

Rick Potts, senior author of the study and the National Museum of Natural History’s Peter Buck Chair of Human Origins, said that 3 million years ago in the dig location would not have been a comfortable place for our ancestors.

“East Africa wasn’t a stable cradle for our species’ ancestors,” Rick Potts said.

“It was more of a boiling cauldron of environmental change, with downpours and droughts and a diverse, ever-changing menu of foods.

The research was led by scientists from the Smithsonian’s National Museum of Natural History and Queens College, CUNY, as well as the National Museums of Kenya, Liverpool John Moores University and the Cleveland Museum of Natural History.

Authors of the paper would also like to acknowledge the National Museums of Kenya for the support and partnership.

Media: Courtney Carthy, +61 487 448 734, c.carthy-oneill@latrobe.edu.au