Researchers have found tools in Kenya that are 3 million years old, showing the development of human ancestors

On a peninsula by a lake in East Africa, archaeologists have found evidence of a society that lived there more than 3 million years ago.

Kenya’s Homa Peninsula is part of the East African Rift Valley, a part of the world often referred to as the “cradle of mankind.” So many oldest traces of the earliest days of mankind are preserved beneath the fertile, human soil of the valley, including the remains of “Lucy”, an ancient human relative who lived more than 3 million years ago.

Tom Plummer and his team are the latest to make a discovery in the area, working at a location on a peninsula called Nyanga. The team found flakes, or small knives, at the excavation site. Blades are believed to be some of the first tools ever used on Earth – and even after more than 3 million years, they still have a sharp edge.

Plummer, an archaeologist at the City University of New York, said the blades were made by striking one stone against another. The knives would have been used to peel and cut fruits and vegetables, and to cut meat from prey like hippos, Plummer said. The meat would then be pounded between stones to soften it. The knife and stones are known as the Oldowan tool set and probably laid the foundation for further technological advances.

“I think Oldowan technology is probably the most important technological innovation that has ever happened in human history,” Plummer told “CBS Saturday Morning.”

“It gave (pre-human ancestors) access to a whole range of foods that they would never have had access to before.”

Plummer said the new diet would stimulate body and brain growth, setting off a “feedback loop” that created more sophisticated creatures that “start doing more with technology.” A similar, even older cutting tool was also found in Kenya, but this technology has apparently died out, so Plummer believes that this very tool is responsible for this development.

“I think it all starts with Oldowan,” Plummer said.

Who made the tools is another surprise. Along with the tool, Plummer’s team found a tooth from Paranthropus, an early hominin that is not a direct ancestor of humans. This suggests that the first tool-making was not a human legacy, but an idea that human ancestors copied and then used to dominate other hominins, who eventually died out.

Rick Potts, director of the Smithsonian’s Human Origins Program and head of research on the peninsula, said the discovery could help shape human existence on the planet.

“We’re the last biped in existence, as I call it,” Potts said. “All these other ways of life have died out. It gives us something to think about and draws attention to the fragility of life, even in our own time travel.”

Searching for prehuman history

The search for these early artifacts has the look and intrigue of an “Indiana Jones” movie. Finding chipped stones that showed evidence of being used as tools was one thing, but the archaeological team then had to find cut marks on animal bones that confirmed how the knives were used.

Blasto Onyango, a local archaeological legend who helped uncover the Turkana boy, the most complete early hominin skeleton ever discovered, said his impressive discovery took “four or five years”. As time passed, he and other archaeologists found “different parts” of the skeleton, working slowly but surely to uncover the remains of a boy who lived more than a million and a half years ago.

Paleontologist Rose Nyaboke said that kind of painstaking, slow research is what makes up the day-to-day work of an archaeological dig. Sometimes, she and other researchers find small pieces of bone, but they have to leave those fragments where they are found.

“We don’t just pick anything. It has to have paleontological significance,” Nyaboke explained. “We say ‘We’re sorry. We can’t pick you today’.”

The bones that are important are the ones that can give context to the area, like pig teeth. Pigs evolved so quickly that their skeletons help determine the age of the surrounding area. The site is too old for carbon dating, and the ancient volcanic ash that preserved the artifacts makes other dating methods too difficult to use. Explorers actually largely abandoned the area after artifacts from the Homa Peninsula led to inaccurate claims of human origins. Despite everything, Potts started digging on the peninsula almost 40 years ago.

“We found a spot that was hard to track, but we didn’t leave because science takes persistence,” Potts said.

That persistence has been rewarded with discoveries like Plummer’s. New technologies have made it easier to date sites, and new discoveries across East Africa have refined researchers’ understanding of human roots. Researchers knew that modern homo sapiens appeared in Africa about 300,000 years ago, but only recently realized that their hominin ancestors began walking on two legs at least 6 million years ago.

“Some of the things that we thought happened in a very short period of time, within the last million years, now span a period of 6 million years,” Potts said. “It involves making tools.”