Scientists working in the desert badlands of northwestern Kenya have found stone tools dating back 3.3 million years, long before the advent1 of modern humans, and by far the oldest such artifacts yet discovered. The tools, whose makers2 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. 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 today in the leading scientific journal Nature.The whole sites surprising, it just rewrites the book on a lot of things that we thought were true, said geologist3 Chris Lepre of the Lamont-Doherty Earth Observatory4 and Rutgers University, a co-author of the paper who precisely5 dated the artifacts.The tools shed light on an unexpected and previously6 unknown period of hominin behavior and can tell us a lot about cognitive7 development in our ancestors that we cant understand from fossils alone, said lead author Sonia Harmand, of the Turkana Basin Institute at Stony8 Brook9 University and the Universite Paris Ouest Nanterre.Hominins are a group of species that includes modern humans, Homo sapiens, and our closest evolutionary10 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 tantalizing11 clues that some other, earlier species of hominin, distant cousins, if you will, might have figured it out.The researchers do not know who made these oldest of tools. But earlier finds suggest a possible answer: The skull12 of a 3.3-million-year-old hominin, Kenyanthropus platyTOPs, was found in 1999 about a kilometer 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.The precise family tree of modern humans is contentious13, and so far, no one knows exactly how K. platyops relates to other hominin species. 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.
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1 advent n.到来，到来 参考例句： Swallows come by groups at the advent of spring. 春季到来时燕子成群飞来。 The advent of the Euro will redefine Europe.欧元的出现将重新概念欧洲。
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