Our bigger brains are certainly a big factor why humans have reached the top of the food chain and there is no sign we are going to be threatened in that position, unless it is by our own hubris. But there is another big differentiator between our species and most of the rest of the primates: Humans are proficient at using tools.

However, there is increasing evidence that other species of primates have also been using tools for their own purposes for hundreds or thousands of years. Chimpanzees in Africa were using tools that were dated back to between 4,300 and 1,300 years old. A recent study, “Archaeological excavation of wild macaque stone tools,” published in the Journal of Human Evolution discussed the use of stone tools by wild macaques in coastal Thailand.

And now, a new paper published Monday in the Current Biology journal demonstrates the use of tools by the Brazilian bearded capuchin monkey, popularly known as organ-grinder monkeys, who “use stones to pound open defended food, including locally indigenous cashew nuts.” The paper adds “that this activity dates back at least 600 to 700 years,” making the “capuchin stone hammers and anvils … the oldest non-human tools known outside of Africa.”

Michael Haslam, lead author of the study, titled “Pre-Columbian monkey tools,” told the Christian Science Monitor: “From a human perspective, capuchin stone tool use appears quite simple. The capuchins are carefully selecting their hammer and anvil stones, and adjusting their striking behaviour, to efficiently open the nuts. It takes the monkeys years to learn how to do this properly, so even though it appears simple, there are actually a lot of parts to the process that need to be learned and practiced.”

In another statement, Haslam suggested the study could throw some light on the possible influence of monkeys’ use of tools on human behavior.

“For example, cashew nuts are native to this area of Brazil, and it is possible that the first humans to arrive here learned about this unknown food through watching the monkeys and their primate cashew-processing industry,” Haslam said.

The findings are important because “a greater understanding of how our primate relatives also use tools in their daily lives gives us a better appreciation both of the way we currently fit into the natural world, and some idea of how our own ancestors may have reached the extraordinary position that we find ourselves in today,” he added.

So when you next see a monkey hitting a big rock with a smaller one, it may not be just plain old monkey business.