Even without prior training, orangutans may be able to use stone tools and apply stone carving techniques, suggests a study published this Wednesday by a team of German and Spanish researchers in the scientific journal Plos One.
In order to reconstruct the emergence and evolution of lithic technologies and the behavior of early hominids in this regard, the scientists analyzed the individual and collective learning capacities of orangutans, as close relatives of humans, in relation to the production and use of stone tools.
In a first experiment, two male orangutans at the Kristiansand Zoo in Norway, who had no prior experience with stone tools, were given a concrete hammer to see if they were capable of hammering the core of a stone to thus open two boxes with pieces of fruit. Although both orangutans spontaneously hit the hammer against the walls and floor, none he used the instrument against the stone.
The scientists also tested the orangutans’ abilities to use ready-made tools by leaving a flake on them. During the experiment, one of the primates managed to open the box with the instrument provided.
In another experiment, to find out if primates could learn stone carving by watching others, scientists studied the behavior of three female orangutans at Twycross Zoo in England, UK. As a result of the carving demonstrations, one of the animals used the hammer to hit successfully the core of a stone.
the first evidence
The authors note that the study shows that while orangutans in the wild do not use stone tools, in captivity they are able to use them when provided. “Our study presents the first evidence that untrained primates also can identify and use a stone sharp-edged like a cutting tool […] even in the absence of proof,” the scientists write.
“Overall, our findings suggest that two prerequisites for the emergence of lithic technologies—lithic percussion and the recognition of sharp-edged stones as cutting tools—could be deeply rooted in our evolutionary past,” they conclude.
