As humans, we might think that we are the first ones to adapt or use tools, but new evidence is showing that primates have been using tiny hammers and other tools to open cashews for over 700 years. In their paper published in the journal Current Biology, scientists at the University of Oxford have even suggested that people knew cashews were safe to eat by observing monkeys crack them open with their primitive tools and eating them. 
Lydia V. Luncz, one of the authors on the study, said:
“We think we’re just at the beginning. We definitely expect this to go beyond 700 years.” 
Researchers say that the 1300’s just happen to be the time the tools were dated, but they have asserted that it now prompts archaeologists to look at whether early humans were inspired by monkeys and other primates to begin their use of tools.
Dr. Michael Haslam, lead author of the study, echoes Luncz’s sentiments that we have much more to learn when it comes to studying the tools of both our ancient ancestors and the ancestors of our primate cousins.
“We definitely don’t think we have the oldest activity.
We only began this project in the last few years and we have to imagine we’re in the same situation as human archaeology was when they started to find the first evidence of stone tools. That [evidence] now goes back more than three million years in Africa.
So we think we’re at the tip of the iceberg.”
Others on the study, such as Dr. Catherine Hobaiter from the University of St Andrews, says that humans may have been underestimating the intelligence of primates for many years. Previously, when researchers have found a tool, they have assumed it was used by humans, however, researchers are learning that this may not be the case.
“Either you don’t have to be smart to make a tool, or we’ve been underestimating other species by a long way.”