A handful of primate species use tools to hunt and perform other tasks, as research has shown since Jane Goodall first witnessed a chimp “fishing” for food in a termite mound in the 1960s.

But now, a new group of white-faced capuchin monkeys have been spotted using heavy stones to bash open certain sources of food, using pieces of wood as a kind of anvil, on an island off the coast of Panama.

The new discovery of an enterprising group of monkeys is reported on the pre-print website run by Cold Spring Harbor Laboratory bioRxiv.

“We then report the first case of habitual stone-tool use in a gracile capuchin: a population of white-faced capuchins (Cebus capucinus imitator) in Coiba National Park,” the scientists, from the Max Planck Institutes for Ornithology and Evolutionary Anthropology and other institutions, wrote.

The gracile capuchin monkey, which is classified as the genus Cebus, has been distinct from its wild robust counterparts genus Sapajus) since 2012. The Sapajus variety have been documented to use a variety of tools but for some reason, their slender counterparts had not.

But on the island of Jicaron (about 2,000 hectares), which was part of the former penal colony for violent criminals and political dissidents, the Cebus groups had been anecdotally seen using tools.

The scientists set up 35 video-camera traps that would record for 30 seconds once triggered. The vast majority, 30, were focused on Jicaron. The scientists also placed experimental hammerstones and wood anvils to capture the behaviors.

The results: over half of the capuchins were observed using tools over an observational period from March 2017 to March 2018.

At the most active sites, 83.2 percent of days captured some kind of tool use. However, only male individuals were seen using the tools.

Primarily, the monkeys collected cobbles collected from streams. They used those rocks to great effects, opening foods such as Teminalia catappa endocarps (otherwise known as sea almonds), hermit crabs, Halloween crabs, coconuts and sea snails.

The three conditions considered important for tool use—high terrestrial behavior, decreased predation pressure, and resource limitations—were all in effect at the Coiba National Park sites.

The other species which have shown ingenuity in using tools are bonobos, chimps, gorillas, Sumatran orangutans and mandrills.

But, recently baboons devised some creative use of obstacles at a Texas facility to escape a pen.

Chimpanzees have also shown dexterity in using leaves to drink a natural palm wine, and get a little drunk, in West Africa.