US: Hyenas prove value of team work

In the animal world, chimpanzees are regarded as the brainboxes. But new research shows that they can't touch spotted hyenas when it comes to cooperative problem-solving.

In fact, the hyenas were so quick at finding solutions to tasks for which primates usually require extensive training that researchers from Duke University and the University of California, Berkeley, were left open-mouthed with amazement.

Researcher Christine Drea, an evolutionary anthropologist at Duke, said social carnivores that hunt in packs like spotted hyenas might be good models for investigating cooperative problem-solving and the evolution of social intelligence.

"What this study shows is that spotted hyenas are more adept at these sorts of cooperation and problem-solving studies in the lab than chimps are. There is a natural parallel of working together for food in the laboratory and group hunting in the wild."

The research saw captive pairs of spotted hyenas (Crocuta crocuta) presented with two ropes, which they needed to tug in unison in order to produce a food reward. The animals figured out how to do the task quickly and with no training.

"The first pair walked in to the pen and figured it out in less than two minutes," Drea said. "My jaw literally dropped."

The research, conducted at Berkeley, also examined how social factors affected the hyenas' performance. When an audience of hyenas was present, experienced animals solved the task faster. But when dominant animals were paired, they performed poorly, even if they had been successful in previous trials with a subordinate partner.

"When the dominant females were paired, they didn't play nicely together," Drea said. "Their aggression toward each other led to a failure to cooperate."

When an animal unfamiliar with the feeding task was paired with a dominant, experienced animal, the hyenas would switch social roles with the dominant animal submissively following the lower-ranking animal. Once the lower-ranked hyena became experienced, they switched back.

Drea said researchers had focused on primates for decades with an assumption that higher cognitive functioning in large-brained animals should enable organised teamwork. But the hyena study demonstrates that social carnivores, including dogs, may be very good at cooperative problem solving, even though their brains are comparatively smaller.

"I'm not saying that spotted hyenas are smarter than chimps," Drea said. "I'm saying that these experiments show that they are more hard-wired for social cooperation than chimpanzees."

The research is published online in the October issue of Animal Behaviour. The co-author of the study is Allisa N Carter of the University of California, Berkeley.