Flints, hammers, anvils, and more found on the western edge of Lake Turkana in Kenya indicate that human relatives have been making and using tools for even longer than we thought. Tool use dates back to 3.3 million years ago, according to a new study in the journal Nature, moving the timeline for when human ancestors began using tools back by 700,000 years. Previous estimates put the development of tools at approximately 2.6 million years ago.

Making and using tools has long been considered a key factor in higher cognition and intelligence, and prehistoric tools provide important insight into how humans evolved. While it’s unclear who made these tools, these artifacts are more than a half-million years older than the earliest fossils scientists have discovered of Homo, the genus that includes the human species and their immediate ancestors. 

Stony Brook University archaeologist Sonia Harmand with a prehistoric tool. Image Credit: MPK-WTAP

The stone tools excavated in Kenya are more primitive than the 2.6-million-year-old evidence of tools found in Ethiopia, but they still indicate that those early human ancestors had decent enough motor control to wield a stone hammer. Markings on the stones suggest that the stones were used to pound things, and some, called cores, were shaved to produce sharp flakes that could have been used for cutting plants or animal material. 

Tools aren’t just the purview of humankind. Several other animals use tools, including a few primates, dolphins, and crows. But unlike humans, they don’t make the tools themselves. While the ability to fashion complex tools has been important to the evolution and survival of the human species, this finding suggests that manufacturing tools was an important part of life even before the earliest humans appeared on the scene. 

A tool found at the excavation site in Kenya. Image Credit: MPK-WTAP

“We know now that at least one group of ancient hominin [humans and their close ancestors] started intentionally knapping stones to make tools long before previously thought,” says study author Sonia Harmand of Stony Brook University in New York. “They show that the knappers already had an understanding of how stones can be intentionally broken, 3.3 million years ago, beyond what the first hominin who accidentally hit two stones together and produced a sharp flake would have had.”