Researchers have found 3 million-year-old tools in Kenya that show the development of human ancestors

Archaeologists have found clues about a society that lived there more than 3 million years ago on a lakeside peninsula in East Africa.

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 of the oldest clues about the first days of mankind were preserved beneath the fertile human soil of the valley, including the remains of “Lucy”, an ancient relative of man who lived more than 3 million years ago.

Tom Plummer and his team are the latest to make discoveries in this area, working at a place on a peninsula called Nyango. At the excavation site, the team found flakes, or small knives. Blades are believed to be among 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 were used for peeling and slicing fruits and vegetables, as well as for cutting off the meat of prey like hippos, Plummer said. The meat was then pounded between stones to make it soft. The knife and stones are known as the Oldowan toolkit and probably laid the foundation for further technological development.

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

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

Plummer said the new diet would have spurred body and brain growth, setting off a “feedback loop” that produced more advanced creatures that “started doing more with technology.” A similar, even older cutting tool was also found in Kenya, but the technology appears to have died out, so Plummer believes that this tool can be credited with these developments.

“I think it all started with Oldawan,” Plummer said.

Who made the tools is another surprise. Along with the tools, Plummer's team found a tooth from a paranthropus, an early hominin that is not a direct human ancestor. This suggests that the making of the first tools is not a human legacy, but an idea that human ancestors copied and then used to dominate other hominids that 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 bipeds, 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 time travel.”

Searching for prehuman history

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

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

Paleontology researcher Rose Nyaboke said the day-to-day work of an archaeological dig consists of painstaking, slow research. Sometimes she and other researchers find small pieces of bone, but have to leave the pieces where they are found.

“We're not picking anything. It has to have paleontological significance,” Nyaboke explained. “We say, 'I'm sorry. We can't pick you up today.''

Bones that matter are those that can give context to an area, such as pig teeth. Pigs evolved so quickly that their skeletons help date their surroundings. The site is too old for carbon dating, and the ancient volcanic ash that preserved the artifacts makes it too difficult to use other dating methods. Researchers largely abandoned the area after artifacts from the Homa Peninsula led to inaccurate claims about human origins. Despite all this, Potts began excavations on the peninsula almost 40 years ago.

“We found a place that is difficult to date, but we didn't leave it because science requires persistence,” Potts said.

This persistence has been rewarded with discoveries such as those made by Plummer. New technologies have made it easier to date sites, and new discoveries in eastern Africa have refined researchers' understanding of human roots. Researchers knew that modern humans appeared in Africa about 300,000 years ago, but only recently did they realize that their hominin ancestors began walking on two legs at least 6 million years ago.

“Some things that we thought happened in a very short period of time, within the last million years, are now stretched over a period of 6 million years,” Potts said. “This includes making tools.”