Capuchin monkeys often use stones to crack nuts. Again and again the stones splinter, so that sharp -edged fragments are created. These discounts often have an amazing similarity to early human stone tools, as a study shows. The results suggest that our ancestors could initially have to generate sharp -edged stone offspring until they noticed that they can be used as blades.
When archaeologists discover stones with characteristic fracture edges in Stone Age sites, they usually assume that our ancestors have consciously made them. The oldest evidence for such early human stone tools comes from the East African Oldowan culture and are up to 3.3 million years old. “The development of stone tool technology is an important milestone in the development of the hominins, which enabled early people to influence their environment,” explains a team around Tomos Proffitt from the Max Planck Institute for Evolutionary Anthropology in Leipzig.
Sound as by -products
But how did our ancestors come up with the idea of working on stones to go for a throat, sounding or scraping? In order to get to the bottom of the origins of the Stone Age tools, Proffitt and his team have observed living monkeys today, which also deal with stones. “Our results question the previous assumption that all sharp -edged discounts have been deliberately manufactured in archaeological finds,” says ProFitt’s colleague Lydia Luncz. “Instead, they indicate that some early stone tools were more by -products from strokes than testimonials of deliberate acts.”
The research team observed yellow breast capuchin monkeys in the Brazilian Fazenda Matos, which hit nuts with stones to crack the hard shell. Due to the impact, parts of the stones always splinter. The monkeys gave no further attention to these fragments, but the researchers took a closer look. “Our analysis of this finds shows many archaeological features that were previously associated with the deliberate production of stone discounts,” reports the research team. “This includes hammer stones with considerable impact damage and a number of cutting and separated pieces.”
Parallels to make the tools of our ancestors
Pruffitt and his team have already observed a similar behavior in other primate species. For example, Makaks in the Thai National Park Phang-NGA also use stones for nuts and create similar stone tools as a by-product. “Our observations at various primate types indicate that stone material that has been unintentionally overturned when using tools should be viewed as a universal by -product when using key tools,” says Pruffitt.
From the researchers’ point of view, the results also provide possible insights into the evolutionary roots of human tool production. “Similar behaviors of the early hominins could also have led to stone discounts, although these artifacts could have been very variable,” explains the team. Maybe our ancestors only came up with the idea of using the splintered parts after a long phase of the unintentional manufacture of such discounts – and consciously producing them in the next step. “By involving the entire spectrum of the documented primate and hominine finds, we can better understand the processes that led to the development of stone tool technology,” says Pruffitt.
Source: Tomos Proffitt (Max Planck Institute for Evolutionary Anthropology, Leipzig) et al., Proceedings of the National Academy of Sciences, DOI: 10.1073/PNAS.2420067122