Some of the First Humans Used Tools Continuously

A newly uncovered trove of ancient stone tools in northwest Kenya suggests early humans didn't use them sporadically but routinely over hundreds of thousands of years, at the very emergence of humanity. Archaeologists at the Namorotukunan site in the Turkana Basin uncovered 1,300 stone flakes, hammerstones, and cores that show evidence of continuous toolmaking over a 300,000-year span, starting around 2.75 million years ago. This challenges earlier assumptions that continuous tool use only came later, when larger brains evolved in humans between 2.4 and 2.2 million years ago, the BBC reports. In fact, tool use "is probably much earlier and more continuous than we thought it was," says David Braun, lead author of a study published Tuesday in Nature Communications.

The findings reveal a long tradition of craftsmanship and knowledge-sharing among some of the first humans. They were "extremely astute geologists" who "knew how to find the best raw materials," Dan Palcu Rolier, a senior geoscientist on the team that uncovered stone tools so sharp they could still cut flesh, tells the BBC. The tools, made using the Oldowan technique—the earliest widespread stone tool technology—appear in three distinct soil layers, each representing a different period in prehistory. Researchers say the quality of the materials and the consistency of the craftsmanship suggest that these ancient toolmakers were highly skilled, carefully selecting rocks from riverbeds and passing their techniques down through generations.

Geological evidence from the site shows that the region's environment shifted dramatically over time, from wetlands to dry grasslands and semideserts, per a release. Researchers believe that rather than adapting biologically to these changes, early humans used their tools to adapt their behavior, giving them a survival edge over other species. Cut marks on animal bones at the site indicate that meat was an important part of their diet, made more accessible by these tools. The region was populated by some of the first humans around 2.75 million years ago, but also human ancestors, the australopithecines. Researchers note the tool users could be a mix of both of these groups, perhaps hinting at a transfer of knowledge across species, per the BBC.