How old are the stone hand axes found in Bose in southern China in the 1970s and 1980s? About 800,000 years, many researchers think. That would mean that ancient Chinese man made tools with an advanced technique previously thought to be only found in more western areas. According to archaeologist Marco Langbroek, however, it is not at all certain that the carved stones are that old.
Our ancestors from the Aucheuléen, a period of the Old Stone Age, were particularly adept at making tools from stone. With a special technique they chopped off shards of stone fragments, until a hand ax, scraper or knife remained. Characteristic of the technique was that the rock fragments were processed on both sides (bifacially). In this way, prehistoric man created a sharp edge, which could be used, for example, to cut or scrape animal skins. A fine example of craftsmanship, for early hunter-gatherers such as the Homo erectus and the Homo heidelbergensis .
The Acheuleen lasted approximately from 1.75 to 0.1 million years ago, but not all prehistoric humans mastered the technique at the same time. The oldest bifacial implements come from Africa, where the Homo erectus made them 1.75 million years ago. On the other continents, the tools made using this technique are considerably younger. For example, bifacial tools older than 500,000 to 600,000 years have never been found in Europe, and the oldest bifacial tool from China has long been estimated to be about 200,000 years old. To the east of the imaginary 'Movius line', which runs through Europe and Eurasia and China, the tools of the Aucheuléen industry were not even present at all, was the idea.
Find
But perhaps that picture needs to be adjusted, Chinese researchers wrote in 2000 in the scientific journal Science. They dated bifacial-made bifacial axes from the Bose Base in Guangxi in southern China to about 800,000 years ago. The tools were found in a soil layer that also contained tektites – solidified droplets of glass that fall to Earth when a meteorite hits. A beautiful and especially useful coincidence, because tektites can be dated very accurately. And since the stone tools were found in the same layer as the tektites, they must be the same age, the researchers wrote.
However, the latter is not true, says Marco Langbroek this month in the Journal of Human Evolution. The layer in which the tektites occur probably consists of material of all kinds of ages. The soil layer containing the tektites shows great similarities with soil layers in nearby Vietnam, Laos and Thailand, where tektites from the same meteorite impact have ended up. These layers are known to consist of a mix of materials of different ages, says Langbroek.
Such layers are created by a process called 'vertical reworking', which boils down to the deflation and collapse of soil layers:The wind blows light particles from the surface, water washes away the fine sand under the solidified glass droplets, and only the heavier material remains. lying down. Even if the bifaces and tektites were originally at different depths, they will all eventually remain in the same layer on the Earth's surface in this way. And that probably happened in Bose, Langbroek thinks.
Intelligence or environment?
The fact that some prehistoric humans made hand axes of stone and others did not, does not automatically say anything about their intelligence or development. It might as well have to do with the material that was in stock to make tools. In China, for example, many tools were probably made of bamboo, which have long since decayed.
In addition, it was decisive which tools our predecessors needed at a given moment, explains Langbroek. Did they have to hunt themselves, or did they live in areas where the leftovers of predators and scavengers could make do? And how far had the carcasses they could possibly find already been eaten? Those kinds of things determine whether you need tools to skin and cut up animals.
Premature
So it cannot be ruled out that the tektites and the hand axes are of the same age, but it has not been proven either. And since the Chinese researchers base their dating solely on these tektites, the conclusion that the hand axes are 800,000 years old is rather premature. Langbroek therefore argues for additional research, in which other material from the soil layer in which the processed stones occur is also dated.
The Chinese researchers do not agree with Langbroek, and already wrote in the same issue of the Journal of Human Evolution a response to his article. They write that there are no indications of the vertical displacement of material in the relevant soil layer. In fact, the fact that you can still see ablation traces on the tektites – damage that occurred when the glass grains traveled through the atmosphere – and that they have not worn off, proves that there was hardly any movement in the soil.
“But there are fallacies in their reasoning,” Langbroek says in turn. For example, the damages to the tektites are not ablation marks at all, but caused by soil acids and groundwater. Bose's tektites consist of material from the Earth's top layer that was melted by the impact, thrown into the air, and immediately solidified in the atmosphere. "Such damage does not occur, the speed is not high enough for that." Langbroek is thus again writing a response to the response of the Chinese scientists. The discussion will probably continue for a while…