A 3 Million-Year-Old Discovery May Rewrite the History of Intelligent Life on Earth

For years, researchers have believed that human ancestors in Ethiopia were the first beings to use crude stone tools, about 2.6 million years ago. But a recently-published study introduces new findings that suggest tool-making occurred over 300,000 years prior, in a completely different location, and by a species that isn't even an ancestor to modern humans.

So-called Oldowan tool-making is often portrayed as something of a landmark in history, allowing for efficient processing of food. The advent of these advanced (at the time) tools is widely seen as a milestone in the development of culture, and has remained a touchstone in scientists’ investigations into the timeline of the emergence of human intelligence. 

The paper in Science—which was co-authored by researchers spanning various institutions—describes a site in Nyayanga, Kenya that dates to 3.032 to 2.581 million years ago. Archeologists have been excavating the site since 2015 and discovered 330 artifacts (including tools), 1776 bones, and two hominin molars—but not belonging to any direct human ancestors. 

“With these tools you can crush better than an elephant’s molar can and cut better than a lion’s canine can,” Rick Potts, senior author of the study and the National Museum of Natural History’s Peter Buck Chair of Human Origins said in a press release. “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 researchers were able to date the tools back to about 2.9 million years ago, much earlier than previous records of stone tool use.

“This is one of the oldest if not the oldest example of Oldowan technology,” Thomas Plummer, an anthropology professor at Queen’s College and the study’s lead author, wrote in a press release. “This shows the toolkit was more widely distributed at an earlier date than people realized.”

While it’s an impressive feat that the tools were made so long ago to begin with, they were also fully functional. Alongside the tools, researchers discovered the bones of two hippos, demonstrating that the hominins were able to utilize the tools to process and eat large animals. 

Most incredibly, the paper also chronicles the team’s discovery of Paranthropus molars. The Paranthropus genus is not an ancestor to modern Homo sapiens, but rather a kind of evolutionary cousin. The molars are the oldest fossilized Paranthropus remains ever found. 

While it is widely believed that Oldowan tools were first used by human ancestors in the Homo genus, the discovery of the tools in conjunction with the molars suggest that our evolutionary relatives may have also wielded these stone tools—and that the real history of the early hominins is more nuanced than we thought. 

“The association of these Nyayanga tools with Paranthropus may reopen the case as to who made the oldest Oldowan tools,” Plummer said in a press release. “Perhaps not only Homo, but other kinds of hominins were processing food with Oldowan technology.”

"We are going to continue collecting dating samples, work on vegetation reconstruction through phytolith analysis (the soils have lots of ancient phytoliths), and continue behavioral studies by investigating a broader range of archaeological sites, including in the vicinity of the freshwater spring," Plummer wrote in an email to Motherboard. “And of course if we found more hominin fossils in the process that would not be bad!"

Update: This article was updated with comment from study lead author Thomas Plummer.