Capuchins are indubitably clever monkeys. Researchers have long observed them using stones as hand-held hammers and anvils to break open hard, shelled food like cashews and seeds, while younglings watch their elders hammer away and learn from observation.
Their geological knowledge was found to be quite astute – anvils were four times heavier than the hammers, and the hammers were four times heavier than the average stones nearby. The anvils tended to be made of layered, flat sandstones, whereas the hammers were forged from pointed, angular quartzite.
Whenever a capuchin is full of delicious nuts, it tends to leave its stone tools by a cache of discarded shells, which over time gets buried by sand and soil. After waiting for the capuchins to scuttle off, the researchers sauntered over to these sites and dug into the ground to see if they could find any older tools.
Using distinctive identifying marks on the tools made by the grinding, slamming, hammering action of long-gone capuchins, 69 tools were successfully excavated from a depth of up to 0.7 meters (2.3 feet), and radiocarbon dated using small pieces of charcoal. The oldest tools were 600 to 700 years of age, which means that 100 generations of capuchins – at least – have been using stone tools. They think it’s only a matter of time until older tools are found.
There is an even more tantalizing prospect to this discovery. The European invasion didn’t occur until the year 1500, so the capuchin Stone Age predates this by around 200 years. The indigenous populations of Brazil, therefore, may have come across capuchins breaking open cashew nuts native to this particular area.
“It is possible,” Haslam notes, “that the first humans to arrive here learned about this unknown food through watching the monkeys and their primate cashew-processing industry.” So instead of monkeys or apes mimicking humans, in this case, it may have been the other way around.
Humans living in the Amazon may have educated themselves about certain stone tools from monkeys once upon a time. ANDRE DIB/Shutterstock