In a discovery that could rewrite the early human history, archaeologists have found the world’s oldest handmade stone tools in Kenya, dating back 3.3 million years, long before the advent of modern humans.

The tools, whose makers may or may not have been some sort of human ancestor, push the known date of such tools back by 700,000 years. They also may challenge the notion that our own most direct ancestors were the first to bang two rocks together to create a new technology, researchers said.

The discovery is the first evidence that an even earlier group of proto-humans may have had the thinking abilities needed to figure out how to make sharp-edged tools.

The stone tools mark “a new beginning to the known archaeological record,” say the authors of a new paper about the discovery, published in the journal Nature.

“The whole site’s surprising, it just rewrites the book on a lot of things that we thought were true,” said geologist Chris Lepre of the Lamont-Doherty Earth Observatory and Rutgers University, a co-author of the paper who precisely dated the artifacts. The tools “shed light on an unexpected and previously unknown period of hominin behaviour and can tell us a lot about cognitive development in our ancestors that we can’t understand from fossils alone,” said lead author Sonia Harmand, of the Turkana Basin Institute at Stony Brook University.

Hominins are a group of species that includes modern humans, Homo sapiens, and our closest evolutionary ancestors.

Anthropologists long thought that our relatives in the genus Homo – the line leading directly to Homo sapiens – were the first to craft such stone tools.

But researchers have been uncovering tantalising clues that some other, earlier species of hominin, distant cousins, might have figured it out.

The researchers do not know who made these oldest of tools. But earlier finds suggest a possible answer: The skull of a 3.3-million-year-old hominin, Kenyanthropus platytops, was found in 1999 about a kilometre from the tool site.

A K platyops tooth and a bone from a skull were discovered a few hundred meters away, and an as-yet unidentified tooth has been found about 100 meters away.

Kenyanthropus predates the earliest known Homo species by a half a million years.

This species could have made the tools; or, the toolmaker could have been some other species from the same era, such as Australopithecus afarensis, or an as-yet undiscovered early type of Homo, researchers said.

The find also has implications for understanding the evolution of the human brain. The toolmaking required a level of hand motor control that suggests that changes in the brain and spinal tract needed for such activity could have occurred before 3.3 million years ago, the authors said.

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