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(The Conversation is an independent, non-profit source of news, analysis and commentary from academic experts.)
Ben Marwick, University of Washington; Bo Li, Wollongong University, and Hu Yue, Wollongong University
(THE CONVERSATION) You probably think of new technologies as electronic that you can carry in a pocket or wrist. But some of the deepest technological innovations of human evolution have been made of stone. Most of the time, humans have been on Earth, they have cut the stone into useful shapes to create tools for all kinds of jobs.
In a study that we have just published in Nature, we have attributed to a distinct and complex method of making stone tools a much older period in China than it had been previously accepted. Archaeologists had thought that such artifacts had been transported to China by migrating groups from Europe and Africa. But our new discovery, dated 170,000 to 80,000 years ago, suggests that they could have been invented locally without the input of other sources, or come from other sources. a much older cultural transmission or human migration.
Many different human species lived on Earth at that time, including modern species like us. But we did not find any human bones on this site, so we do not know what kind of man made these tools.
These Chinese artifacts provide additional evidence that changes the way we think about the origin and spread of new stone tool technologies. And, curiously, we made our discovery on the basis of objects found in excavations decades ago.
New technology among old stones
Archaeologists have identified five methods used by humans to make stone tools over the last 3 million years. Each mode is represented by a new type of stone tool that is radically different from what was before. The appearance of each new mode is also marked by a sharp increase in the number of steps needed to create the new type of tool.
One of these modes, Mode III, also called Levallois, is at the center of several major debates on human evolution. The Levallois tools are the defining features of the Middle Paleolithic or Middle Stone Age archaeological period of Africa. They are the result of a series of very specific steps of chipping a stone to create tools of similar size that can be shaped for various purposes. These steps are remarkable because they are a much more efficient way to produce many useful cutting tools, with a minimum of wasted stone, compared to previous technologies.
One of these debates is whether Mode III tools were invented in one place and then expanded, or independently invented in several different places. Since the oldest, most secure, dated tools from Levallois were discovered in North Africa about 300,000 years ago, it is possible that they will depart from there, carried away by groups of young men migrating across Europe. and Asia. On the other hand, discoveries of Levallois tools of the same period in Armenia and India are in line with the idea of independent inventions of the technology outside the. Africa.
Change the chronology in China
In China, it was difficult to find evidence of the Mode III tools until relatively late in the Paleolithic, about 30,000 to 40,000 years ago. This is what happens when Mode IV (blade tools) appears there. In China, the ancient peoples seemed to go from mode II (stone axes) to modes III and IV at the same time. This suggests that Levallois tools appeared in China when modern humans emigrated and brought these new technologies with them about 30,000 to 40,000 years ago.
Our results corroborate the different story of the origin of Levallois tools in China. In Guanyindong Cave, Guizhou Province, south-central China, we found Mode III tools in layers of about 170,000 and about 80,000 years ago. This puts them well before the tools of Mode IV and around the same time as Levallois were the main tools used in Europe and Africa.
One of the major consequences of our beginnings in the Guanyindong cave is that the appearance of Levallois tools in China is no longer linked to the arrival of modern humans and Mode IV tools 30,000 to 40,000 years ago. Instead, Levallois tools could have been invented locally in China – perhaps by a different human species. Another possibility is that they were introduced by a much older migration, perhaps by people whose teeth were found in a cave in Daoxian, Hunan Province, who lived between 80,000 and 120 000 years.
Back to Guanyindong Cave
Our discovery is a little unusual because we have not made new major excavations. All of the stone tools we studied were excavated in the Guanyindong Cave in the 1960s and 1970s. Since that time, Guanyindong has been known as one of the most important Palaeolithic sites in southern China because of relatively large number of stone tools found in this region.
Most of them are stored at the Institute of Paleontology and Paleoanthropology of Vertebrates in Beijing, and our team spent a lot of time thoroughly inspecting each tool to identify the traces that reveal its manufacture. It is during this careful analysis of museum specimens that we encountered a few dozen Levallois tools among the thousands of artifacts in the collection.
During previous excavations in the Guanyindong Cave, researchers had used uranium series methods to date the fossils found in sediments. This technique relies on the radioactive decay of tiny amounts of uranium that accumulate in the bone shortly after burial, allowing an age interval to be set for burial. But it is difficult to accurately determine the true age of the bones with this method. In Guanyindong, these ages of the uranium series span a wide range from 50,000 to 240,000 years ago. In addition, the association between dated fossilized coins and stone artifacts has not been recorded in detail. These problems meant that we could not know which layers came from the dated fossils and whether they were close to one of the Levallois stone tools.
Using only the information available during previous excavations, we can not be sure of the exact age of Levallois tools in the museum. It was important to set dates, because if they were more than 30,000 to 40,000 years old, they could then be the first Levallois tools found in China.
To discover the true age of these tools Levallois, we made several trips in the cave to collect new samples for dating. It was difficult to find a suitable place to collect the samples because the previous excavations left little behind and much of the site was covered with thick vegetation.
We collected our new sediment samples at locations where artifacts were still visible in the wall of the excavation, so we could be sure of a close connection between our samples and the stone tools. Essentially, we were trying to collect new dirt where the artifacts of the museum had been exhumed. The plan was then to test the samples with more advanced dating techniques than those initially available.
Analyze new samples to date ancient artifacts
Back in the laboratory, we analyzed the samples using luminescence methods stimulated optically by a single grain. This technique allows to identify the elapsed time since the last exposure of each grain to the sun. The dating of many individual grains in a sample is important because it can tell us whether the roots of trees, animals or insects have mixed younger sediments into older sediments. After identifying and eliminating the intrusive young grains, we discovered that a layer of artifacts dated back about 80,000 years ago. We dated from a layer less than about 170,000 years ago. Our work at the museum had identified the Levallois tools in these two layers.
Through a combination of careful inspection of the museum's collection, new fieldwork for sample collection and a new laboratory dating method, we have discovered a surprising and important result. These Levallois tools are much older than those of any other site in East Asia. This suggests a wider geographical distribution of Levallois before the dispersal of modern humans outside of Africa and Europe in Asia.
One of the reasons why it was so difficult to find evidence of the technique in China until now is that the number of people in East Asia during the Paleolithic could have been much smaller than in the West. Small populations with low population density, characterized by weak and irregular patterns of social activity, could hinder the spread and persistence of new technologies.
We do not know what kind of man made the tools in Guanyindong because we did not find any bones. Whatever they were, they had similar skills to those living in the West at the same time. They seem to have independently discovered the Levallois strategy in China at a time when it was widely used in Europe and Africa.
This article is republished from The Conversation under a Creative Commons license. Read the original article here: http://theconversation.com/new-dates-for-ancient-stone-tools-in-china-point-to-local-invention-of-complex-technology-106914.
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