(CN) – A newly discovered archaeological site in Ethiopia shows modern humans began incorporating stone tools into daily life about 60,000 years earlier than previously thought, suggesting our ancestors independently invented stone tools many times before then, according to a new study published Monday.
The flaked stone cutting tools at the Bokol Dora 1 excavation site in Ledi-Geraru in Ethiopia show modern humans began regularly making and using stone tools around 2.6 million years ago, according to the study published in Proceedings of the National Academy of Sciences. Previously, regular stone tool production was believed to have appeared between 2.55 million and 2.58 million years ago.
The organized manufacture of flaked stone tools is a major milestone in human technology and "appears to mark a systematic shift in tool manufacture that occurs at a time of major environmental changes," according to the paper.
The earliest stone tools – found in Lomekwi, Kenya, and used to hammer food items like nuts – are 3.3 million years old and predate our genus, Homo. The find at Bokol Dora 1, or BD 1, consisting of animal bones and hundreds of small pieces of chipped, sharp-edged stone, have been classified as Oldowan, a newer technology emphasizing cutting.
No one knows who made either the Lomekwian or the Oldowan tools, though archaeologists have ventured some guesses. According to David Braun, the paper's lead author and an archaeologist at George Washington University, the only hominin known to have lived in the Lomekwi region was Kenyanthropus Platyops. The Oldowan tools may have been made by a hominin referred to simply as "Early Homo."
Hominins are primates characterized by bipedalism, smaller canine teeth and bigger brains. Modern humans are the only hominins alive today.
Researchers believe that about 2.6 million years ago, our direct ancestors got better at striking the edge of larger stones to make sharp-edged knives like those at BD 1. The shift to using knives to cut up food before eating it coincided with a reduction in the size of their teeth, and the BD 1 artifacts capture it, they say.
"The BD 1 assemblage, near the origin of our genus, provides a link between behavioral adaptations – in the form of flaked stone artifacts – and the biological evolution of our ancestors," the paper said.
Braun and his colleagues had expected to see an evolution between the earliest Oldowan tools at BD 1 and the older Lomekwian tools, which are similar to those used by modern primates.
But they didn't find one. This suggests our ancestors invented stone tools multiple times before incorporating them into everyday life 2.6 million years ago, they say. New evidence may bear this out.
"We have already identified further archaeological sites in the region," Braun said by email. "These sites preserve exciting new evidence of this behavior in the past."
Braun said he and his team hope to publish this research soon.
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