Ecological Opportunity Prompts Tool Use Among Primates

Scientists had assumed that like humans, primates would use tools in times of hardship, for instance when food was scarce. But a surprising new finding indicates that that's not the case. Only does ecological opportunity, rather than necessity, prompt tool use among these non-humans, according to recent research.

Primates use all kinds of tools in the wild to acquire food resources. For example, chimpanzees use stones to crack open nuts and sticks to harvest aggressive army ants. Orangutans also use stick tools to prey on insects, as well as to extract seeds from fruits. Bearded capuchin monkeys that live in savannah-like environments also use a variety of tools also employ the stone method for nuts while utilizing sticks to dig for tubers.

But these primates did not invent such tools because they needed to - a realization that seemed counterintuitive to researchers. Rather than prompted by food scarcity like they previously thought, tool use is simply determined by the local environment. When chimps, orangutans and bearded capuchin monkeys alike encounter calorie-rich but hard-to-reach foodstuffs, such as nuts and honey, it seems to act as an incentive for an ingenious use of materials.

"By ecological opportunity, we mean the likelihood of encountering tool materials and resources whose exploitation requires the use of tools. We showed that these ecological opportunities influence the occurrence of tool use. The resources extracted using tools, such as nuts and honey, are among the richest in primate habitats. Hence, extraction pays off, and not just during times of food scarcity," Dr. Kathelijne Koops of the University of Cambridge said in a statement.

The idea that the environment is a bigger influence on primates than originally believed changes the "method of exclusion" argument - the theory that simple ecological and genetic differences alone cannot account for the variation in behavior between humans and non-human primates - such as tool use.

"Given our close genetic links to our primate cousins, their tool use may provide valuable insights into how humans developed their extraordinary material culture and technology," Koops added.

The findings are published in the journal Biology Letters.