Our ancestors may have been on the move out of Africa 300,000 years earlier than we originally thought.
A recently published study has the anthropological community abuzz. Artifacts recovered from Shangchen in the Loess Plateau, which is located about 750 miles south of Beijing, have been dated to 2.1 million years ago. These findings challenge the previously established evidence for the oldest human ancestors outside of Africa which came from a cave in Dmanisi, Georgia. Fossilized remains, including skulls, dated those finds to 1.8 million years old; the delta between the artifacts from the Loess Plateau and Dmanisi places human activity in the Asia 300,000 years earlier.
The artifacts from the Loess Plateau include stone tools—96 stone points, flakes, and cores—but no human remains. For some researchers, this may present a challenge, as human remains are taken to certify that artifacts are manufactured rather than formed through natural processes, and provide an established and recognizable basis for dating. However, given all that we know about stone tool manufacturing this seems to be a tenuous challenge at best.
Aside from the serration that suggests the pieces were shaped, there is also the very simple reality that human remains are rare. Conditions need to be just right for human remains to be preserved in nature. However, material evidence can be more readily available. A hominin could have potentially created hundreds of stone tools in a lifetime, which can be preserved through a variety of contexts. It is more likely that we can find material evidence of occupation before we find actual remains. As our ancestors moved throughout the landscape, they would have left traces like this. Not every significant find will be ceremoniously arranged around human remains.
The absence of human remains, however, means it's not immediately clear who is responsible for the tools. The hominin species found at Dmanisi is Homo erectus and is known for its toolmaking abilities. But the oldest H. erectus dates to 1.8 million years old, and is roughly 300,000 years younger than the oldest tools found at Shangchen. This opens the door for the possibility that an earlier member of the genus Homo left Africa and migrated to China. We don't yet know if it's a species we already know, or if it is perhaps a species deserving of it's own classification, but perhaps some of the Asian specimens assigned to the grouping of H. erectus deserve a second assessment.
The hominin migration out of Africa was not a singular event. Homo erectus migrated out of Africa into Eurasia, dispersing throughout the Old World and reaching as far as Southeast Asia around 1.9 million years ago. But H. heidelbergensis, the ancestors to Neanderthals and Denisovans left Africa for Eurasia about 500,000 years ago. Modern humans are descendants of a group of Homo sapiens who left Africa about 70,000-60,000 years ago. There were also likely periodic migrations back to Africa with travel being dictated by any number of factors ranging from food and climate. H. erectus is attributed with the physical ability to have traveled this distance, but we don't fully understand the factors that could have prompted such a migration or why they may have been limited to only this group.
The beauty of science is that it is testable and revisable. This find challenges what we have known but also reveals something about our evolutionary history, creating a greater understanding of the hominin population of the planet. As greater analytical processes become available to us, we may wind up rewriting our understanding of Old World cultural development, and undoing some established assumptions, which can only make us a better society overall.
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