A new discovery reveals that hominins left Africa considerably earlier than we imagined and settled in China some 2.1 million years ago, reports Science Magazine.
This conclusion comes from an expedition into the Loess Plateau in north-central China, where archaeologists led by Prof. Zhaoyu Zhu of the Chinese Academy of Sciences uncovered dozens of ancient stone tools — the oldest hominin artifacts to ever be discovered outside Africa.
These precious artifacts were unearthed in the Shangchen site, a sedimentary area lying in the south of the 250,000-square-mile (640,000 square kilometers) plateau which, according to a new study describing the find, “is a newly discovered Palaeolithic locality […] near Gongwangling in Lantian county.”
In total, the archaeologists dug up 96 stone points, flakes, and cores, buried within 17 layers of sediment, which the team estimates to be as much as 2.1 million years old, notes the New York Times.
Since the sediments at Shangchen don’t contain volcanic minerals, which are necessary for radiometric dating, the researchers had to turn to paleomagnetic dating, which studies ancient rocks to pick up known reversal events of our planet’s magnetic field.
The investigation concluded that the stone tools found at Shangchen — which include a notch, scrapers, cobble, hammer stones, and pointed pieces, states Phys.org — are between 1.26- and 2.12-million-years-old.
Before this incredible find, the earliest hominin evidence to be found outside of Africa was discovered in Dmanisi, Georgia, and consisted of human fossils and stone tool fragments dating back to 1.85 million years ago.
The oldest of the newfound stone stools unearthed in China precede the Dmanisi skeletal remains and artifacts by 250,000 years, notes Phys.org, citing the University of Exeter in the U.K.
“This discovery implies that hominins left Africa earlier than indicated by the evidence from Dmanisi,” the authors wrote in their paper, published today in the journal Nature.
In fact, they seem to have gotten out of Africa about a quarter of a million years earlier, which forces researchers “to reconsider the timing of when early humans left Africa,” says study co-author Prof. Robin Dennell, an archaeologist at Exeter University.
Given the age of the Shangchen artifacts, now the oldest remnants of early human occupation in a territory found outside Africa’s borders, the hominins who built them were very primitive and may have actually been small bipedal apes, whose brain size was comparable to that of chimpanzees.
Found buried alongside 2.1-million-year-old animal bones, the stone tools speak to the importance of this new skill in the evolution of mankind, Dennell points out.
“Suddenly you had a primate that could obtain meat from a carcass, and it opened up a new world for them. That simple technology was enough to get them out of Africa and right across Asia.”
This seems to support the theory shared by a minority of researchers who claim that Homo erectus wasn’t the first hominin to leave Africa and was actually beaten to the punch by a more primitive hominin species. According to this theory, this ancient hominin ancestor left Africa and settled in Asia, where it later gave rise to Homo erectus.
Considering that the earliest evidence of Homo erectus in Africa dates back to 1.8 million years ago, a few hundred years after the Shangchen artifacts were left behind in China, this key human ancestor “may have evolved in Eurasia and migrated to Africa,” says geoarchaeologist Reid Ferring of the University of North Texas in Denton, who dated the Dmanisi site.
While the identity of the early humans that left behind the Shangchen stone tools hasn’t been established yet, there’s still more to learn about them just by looking at the artifacts.
Made primarily out of quartzite and quartz, the earliest hominin stone to hail from China probably came from the foothills of the Qinling Mountains found some six miles (10 kilometers) south of Shangchen.
The sediments that have held the stone tools for so long yielded a second discovery, namely that — although primitive — the early humans that lived in Shangchen for roughly 850,000 years were already very adaptable to different climate conditions.
This is because, of the 96 stone tools, 80 were found in 11 sediment layers that deposited in a warm and wet climate, whereas the remaining 16 were unearthed from six sediment layers that formed under cold and dry weather conditions.
“Already before 2 million years, hominins were able to cope with a range of environmental conditions,” says archaeologist Wil Roebroeks of Leiden University in the Netherlands, who was not involved in the study.