Experts Says “Another non-human primate has entered the Stone Age…”

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According to  Colin Barras New Scientists, “Another non-human primate has entered the Stone Age – the fourth type known to have done so. One population of white-faced capuchins living in Panama routinely use stones to smash open nuts and shellfish. Other nearby populations don’t make use of stone tools, which might suggest that primates – perhaps including our ancestors – stumble into the stone age by chance.”

It already been shown that chimpanzees in west Africa and macaques in Thailand and several species of tufted, strongly built capuchin monkeys living in South America use stone tools to improve the quality of their lives by making everyday task easy to do. Now researchers are looking at a population of white-faced capuchin monkeys in Panama who have entered the Stone Age by using stone tools to break nuts and shellfish – just as our earliest ancestors did ages ago.

In an abstract on BioArXiv entitled: 

Habitual stone-tool aided extractive foraging in white-faced capuchins, Cebus capucinus

Habitual reliance on tool use is a marked behavioral difference between wild robust (genus Sapajus) and gracile (genus Cebus) capuchin monkeys. Despite being well studied and having a rich repertoire of social and extractive foraging traditions, Cebus sp have rarely been observed engaging in tool use and have never been reported to use stone tools. In contrast, habitual tool use and stone-tool use by Sapajus is widespread. We discuss factors which might explain these differences in patterns of tool use between Cebus and Sapajus. 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, Panama who habitually rely on hammerstone and anvil tool use to access structurally protected food items in coastal areas including Terminalia catappa} seeds, hermit crabs, marine snails, terrestrial crabs, and other items

New Scientist says the monkey inhabit Jicarón island, a small island off the coast of Panama and part of the Coiba National Park. They also report that only the males in a particular region of the island use them raising question as to why? Is there an evolutionary bias at work?  A paper with the findings is currently available on BioArXiv. says that:

This behavior has persisted on one island in Coiba National Park since at least 2004. From one year of camera trapping, we found that stone tool use is strongly male-biased. Of the 205 unique camera-trap-days where tool use was recorded, adult females were never observed to use stone-tools, although they were frequently recorded at the sites and engaged in scrounging behavior. Stone-tool use occurs year-round in this population, and over half of all identifiable individuals were observed participating. At the most active tool use site, 83.2% of days where capuchins were sighted corresponded with tool use. 

“We were surprised that this behaviour appears to be geographically localised,” lead author Brendan Barrett at the Max Planck Institute for Ornithology told New Scientist.

IFLS says, “The first report of this behavior in the park’s monkeys dates back to 2004, when co-author Alicia Ibáñez noticed the monkeys using stone tools. Researchers went back in March 2017 and placed camera traps across the three islands to catch the monkeys in the act.

The team witnessed the male monkeys break coconuts, crabs, and snails. However, it is unclear why this behavior is not more spread out to other groups on the island. The researchers note that individual monkeys move between groups, so in theory the innovation should spread.

The team suggest that it is possible that entering the Stone Age has a chance component to it, rather than being an expected trajectory for primates. Perhaps, for example, a smarter-than-average individual began using the tools and the others copied him. Given limited food options, tools can increase their chance of survival.

The team hope that more research and further observations of these monkeys will help explain what is going on.

The white-faced capuchins are the second American species to enter the Stone Age. Another group of capuchins, found in South America, use stone tools and may have done so for 700 years. The other two species are macaques in Thailand and chimpanzees in West Africa.”