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The stone tools of an archaeological site in China are as old as 2.1 million years old. Credit: Zhu et al. / Nature 2018
Hominins At least 2.1 million years ago, researchers say in an article on July 11 Nature 1 ]. The stone tools they found in central China represent the earliest known evidence of humans or their ancestors living outside of Africa.
Other scientists are convinced that the tools were made by hominids and that they are as old as claimed. And although the tool makers are unknown, the discovery could force researchers to reconsider what species of hominid left Africa – and when. William Jungers, paleoanthropologist at Stony Brook University, New York
Most researchers say that hominids – the lineage of human evolution – have left their African homeland for the first time there is about 1.85 million years old. since. It is the age of the oldest hominid fossils discovered beyond Africa – in Dmanisi, Georgia, in the region of Caucasian Eurasia. The oldest remains of East Asian hominids, two incisors of southwestern China, date from about 1.7 million years ago (see Hominids). itinerant). The archaeological discoveries made between 2004 and 2017 on a site called Shangchen in central China defy this orthodoxy. By studying and dating a succession of ancient soils and wind dust deposits, a team of Chinese and British geologists and archaeologists led by Zhaoyu Zhu at the Institute of Geochemistry of the Chinese Academy of Sciences discovered dozens of relatively simple stone tools. The youngest tools date back 1.26 million years and the oldest date back to 2.12 million years
. The 2.12-million-year-old geological strata may not even represent the first hominid occupation of the region. John Kappelman, an anthropologist and geologist at the University of Texas at Austin and one of the newspaper's referees, points out that the deepest layers of the site are currently inaccessible because the region is actively exploited 2 ] Research should be a priority, he says
Polarity pattern
The deposits have been dated using a method called paleomagnetism, which uses well-documented flips in the Earth's magnetic field to date the rock established between these events. The structure of geomagnetic flips between 1.26 and 2.12 million years ago is recorded in magnetic minerals enclosed in sediments of Shangchen
Jan-Pieter Buylaert, a geologist at the University of New York. Aarhus in Denmark, who worked on sediments in this region of China, calls the dating "robust".
Archaeologists are also convinced that the tools are authentic. Co-head of the study, Robin Dennell, an archaeologist at the University of Exeter, UK, says his team has ruled out any natural process, such as churning. a river, which can make the rocks look like tools. The ancient rivers are not known on the site of Shangchen, and the proposed tools are the only big stones present.
The lack of alternative explanations of the fractures seen on the stones is sufficient to persuade Zeljko Rezek, archaeologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. "The bottom line: I think they are real stone tools," he says.
Michael Petraglia, archaeologist at the Max Planck Institute for the Science of Human History in Jena, Germany, and another criticism the tools are compelling. They are relatively simple, but it is a feature common to all stone tools that are so early in the archaeological history, he says
Hidden Identity
The identity of their authors is, unclear: no hominin bones have been recovered in Shangchen. "We would all like to find a hominin – preferably one with a tool in his hand," says Dennell. Homo erectus is a possibility, as some of the earliest members of this species have been found in Dmanisi. But Dennell thinks Shangchen toolmakers belonged to an earlier species of the genus Homo .
Petraglia and Rezek both say that the age of the tools – not to mention the possibility that hominins arrived in China even earlier than the 2.12 million mark – suggests that the The toolmaker was a species such as Homo habilis . It is thought that this relatively small hominid was confined to Africa between 2.4 million and 1.4 million years ago.
Jungers maintains the possibility that the Shangchen toolmaker was a species of Australopithecus a group of more homonymous monkeys to whom belongs the iconic fossil Lucy. Up to here, all Australopithecus fossils have been discovered in Africa.
New discoveries imply that hominins covered vast distances before 2 million years – Shangchen is 14,000 kilometers from the nearest sites in East Africa. of this age have been found. According to Vivek Venkataraman, an evolutionary ecologist from Harvard University in Cambridge, Mbadachusetts, Shangchen tool makers, the hunter-gatherers, simply followed their food.
Shangchen Findings Will Probably Encourage Other Researchers to Look for Other Signs According to Kappelman, two million years ago, hominids lived in Eurasia.
Some claims of this kind concerning the first Eurasian hominids have already been made. In 2016, for example, researchers presented traces of stone tools dating back 2.6 million years in a site near the Indo-Pakistan border 3 .
Dennell, who worked in this area, is sympathetic to the idea of an early hominin presence there, but he says the evidence is not as clear as his team found in Shangchen. To prove a hominian presence on any archaeological site, he explains, requires establishing that the tools are real and that their geological context and dating are solid. "It means you have to kiss a lot of frogs before finding a princess."
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