Monkeys Have Used Stone Tools For At Least Seven Centuries

The researchers discovered that Brazilian Capuchins have used stone tools to crack open the cashew nuts for at least seven hundred years.

The study was printed in Current Biology. It was led by Dr. Michael Haslam of the University of Oxford. The study raises questions about the origins and spread of tool use in New World monkeys. This also prompts the researchers to look whether the early human behavior was motivated by their observations of monkeys using stones as tools, according to Science Daily.

In the previous studies of Dr. Haslam, they showed that wild macaques in coastal Thailand used stone tools for decades to open nuts and shellfish. In the recent study, the researchers watched wild capuchins use stones as hand-held hammers and anvils to pound open hard foods such as cashew nuts and seeds. The young monkeys are learning from older ones how to use the tools and open the nuts. The capuchins select stones that are lying around. They picked certain materials, using smooth, hard quartzite stones as hammers, while flat sandstones became anvils. The stones that are used as anvils were over four times heavier than hammer stones. On the other hand, the hammers were four times heavier than average natural stones.

The researchers mined a total of 69 stones and dug a depth of 0.7 meters at a site close to cashew trees where they had seen modern capuchins often using their stone tools. They examined the tools. This includes the size and the shape of the stones and the distinctive damage on the stone surface caused by capuchin pounding. The researchers confirmed that the dark-colored residues on the tools were specifically from cashew nuts using the spectrometry. They also carbon dated small pieces of charcoal found with the stones to form the oldest were least 600 to 700 years old. This means the tools preexist the arrival of Europeans in the New World.

The study suggests that capuchins went through the Stone Age centuries ago and passed that knowledge down from generation to generation. The behavior of the capuchins follows that of the West African chimps, which they did the same with their technology, according to a 2007 study.

Lydia Luncz, the co-author of the study said that it's just handful of primates living today out of 350 that show this kind of behavior. She further said that they need to look back at other species that used tools as noted by Washington Post.