In a remote valley of the Brazilian Serra da Capivara National Park, a group of bearded Capuchin monkeys uses round quartz stones to crack cashew nuts on tree roots or other rocks. Archaeologists have found at least 3000 years old tools under their feet.
The Côte d'Ivoire chimpanzees have been using such stone tools for more than 4,000 years. Therefore, the new discovery is not the oldest known evidence of the use of nonhuman tools. Nevertheless, these Capuchins have something special ( Sapajus libidinosus ).
For about 450 generations, the monkeys visiting this site seem to have adapted their tools to the times. The latest archaeological excavation found 122 capuchin-stone artifacts of varying sizes believed to be related to a different hardness or type of food.
The authors claim that it is the first example of a long-term tool variation that has ever been discovered outside of humans.
"What is really interesting about the ability to perform archaeological excavations in places where primate tools are used is that we as a species are not unique in having a truly fine-grained and detailed archaeological record," he said Study co-author, archaeologist Tomos Proffitt, tells National Geographic .
"This excavation of Capuchins shows that this primate species in Brazil has its own archaeological records, and they have their own antiquity for tool use." [1
Then, about 300 years ago, something changed. At this time, the bricks that the capuchin used to hammer appear much larger than those currently used – suggesting that the monkeys still were not targeting cashew nuts. The evidence suggests that the percussive activity of the Capuchins is at this time The authors suggest that the focus was less on cashew nuts than on the opening of harder foods.
It did not take more than a century Several years ago, the Capuchins in this area used rocks prepared for pounding these tough cashews.
According to the findings to date, the authors can not determine whether the same Capuchin population is responsible for this tool history from the Stone Age, or whether the archaeological records belong to several different populations that settle in this area at different times.
Es i It is also unclear why these changes were made at all. Could it be that cashew nuts used to be less common in the region in the past, or the older tools simply lost their cashews over time?
Reading in these results is difficult, especially as the monkeys have barely changed their hammering technique, just the size of the hammer. Without further context, the authors only need to conclude that "Capuchins who operated within the same basic stone tool tradition for at least 3,000 years have implemented this technology for different purposes."
The study was published in Nature Ecology and Evolution .