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Earliest evidence of our human ancestors outside of Africa found

One of the artifacts being excavated from a layer which is 2.1 million years old. The artifact here is a stone from which three flakes were removed. Credit: Zhaoyu Zhu

Our ancient human relatives were more than scientists had previously thought. Researchers in China have unearthed stone tools that were probably made by our human ancestors some 2.12 million years ago — the earliest evidence ever discovered of the human lineage out of Africa.

“It suggests a way earlier migration from Africa than we ever could have imagined,” said Michael Petraglia, a paleoanthropologist at the Max-Planck-Institute for the Science of the Human History, who was not involved in the study. “It is very exciting.”

Archaeologists from China and the United Kingdom discovered dozens of quartz and quartzite stones on Shangchen, China, on the loess steppic grasslands Plateau, with the name for the yellowish-gray sediment (the so-called loess steppic grasslands) dominates the landscape. The site is geologically unique in that it contains several layers of loess steppic grasslands: a fine, windblown sediment stacked in layers dating from 1.26 million to 2.12 million years ago in the area where the artifacts were found. [See Photos of Our Closest Human Ancestor]

Hominins, which have their origin in Africa to 6 million years ago, are the species that arose after the human lineage, or the Homo – genus, and split from that of chimpanzees. To date, scientists have discovered hominin artifacts and fossils from 1.5 million to 1.7 million years ago at various places outside of Africa. Until now, the earliest evidence of hominins outside of Africa came from a skeleton and artifactslinked to Homo erectus and dated to 1.85 million years ago. These were found in Dmanisi, in the Republic of Georgia, in 2000.

Several pieces of evidence, a strong case for the researchers’ interpretation and dating of these stone tools, the scientists said.

“On the one hand, you feel happy, because you do not often place objects in their original context,” said study co-author Robin Dennell, a paleoanthropologist at the University of Exeter in the United Kingdom, referring to the fact that the artifacts were in the original layer of the sediment. But on the other hand, he said, it is important to be skeptical and careful when analyzing such ancient pieces.

“The most important point to establish is that they are real artifacts,” Dennell told Science in an e-mail.

For an untrained eye, the stones may seem to be the product of natural processes, micro-chipped and cut in the time. But the experienced researchers in Dennell’s team noticed how the flaking of the stone was repeated to create lines in various directions.

The other big sign that the stone tools: The are loess Plateau, is a stone-free landscape. “There are no natural processes that might have flakes of these items, so that you know, that it flaked object could only have been flaked by an early human,” Dennell told Live Science.

The presence of these stone tools suggesting that human ancestors left Arica roughly 10,000 generations earlier than previous estimates suggested. But the experts are not yet sure which species of hominin was actually making the tools, said Petraglia.

“It could have been Homo erectus, but since it’s so early, it is also possible it is a still older ancestor,” Petraglia said. “It really opens all kinds of questions with regard to the migrations from Africa and the ability of these people to adapt to the different ecological conditions.”

Their study was published today (11 July) in the journal Nature.

Original article on Live Science.

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