2.9-million-year-old toolkit in Kenya raises new questions

New, exciting research has revealed some of the oldest stone tools ever found — as old as 2.9 million years — to butcher hippos and pound plant material. The study unveils what could likely be the oldest examples of a significant stone-age innovation known as the Oldowan toolkit. 

Led by an international group of scientists, the excavations related to the study were carried out at the site named Nyayanga, located on the Homa Peninsula in western Kenya.

"Though multiple lines of evidence suggest the artifacts are likely to be about 2.9 million years old, the artifacts can be more conservatively dated to between 2.6 and 3 million years old," lead study author Thomas Plummer of Queens College, research associate in the scientific team of the Smithsonian’s Human Origins Program, said in a statement.

The excavations began in 2015

Additionally, a pair of gigantic molars belonging to the human species’ close evolutionary relative Paranthropus was also found at the site. According to Rick Potts, senior author of the study and the National Museum of Natural History’s Peter Buck Chair of Human Origins, the teeth are the oldest fossilized Paranthropus remains yet found. 

And their presence at a site with stone tools raises "intriguing questions" about which human ancestors can be credited.

"The assumption among researchers has long been that only the genus Homo, to which humans belong, was capable of making stone tools,” Potts said. "But finding Paranthropus alongside these stone tools opens up a fascinating whodunnit."

The site also featured at least three individual hippos, two of which were incomplete skeletons that showed signs of butchery.

The series of excavations, which began in 2015, returned 330 artifacts, 1,776 animal bones, and two hominin molars.

What does the Oldowan toolkit contain?

The Oldowan toolkit includes three types of stone tools: hammerstones that can be used to hit other rocks to make tools, cores that can help split a piece, and flakes that can be used as a cutting or scraping edge or further refined using a hammerstone.

"With these tools, you can crush better than an elephant’s molar can and cut better than a lion’s canine can," Potts said. "Oldowan technology was like suddenly evolving a brand-new set of teeth outside your body, and it opened up a new variety of foods on the African savannah to our ancestors."

The Oldowan toolkit is said to have spread as far as modern-day Georgia and China and was not replaced or amended until some 1.7 million years ago.

The research team was able to date the items recovered using "a combination of dating techniques, including the rate of decay of radioactive elements, reversals of Earth’s magnetic field and the presence of certain fossil animals whose timing in the fossil record is well established".

Significance of the discovery

The study gives a glimpse of the world inhabited by our ancestors and describes the ways that stone technology helped early hominins adapt to different environments.

"East Africa wasn’t a stable cradle for our species’ ancestors," Potts said. "It was more of a boiling cauldron of environmental change, with downpours and droughts and a diverse, ever-changing menu of foods. Oldowan stone tools could have cut and pounded through it all and helped early toolmakers adapt to new places and new opportunities, whether it’s a dead hippo or a starchy root."

The study was published on February 9 in the journal Science.