Research hints gorillas smarter than previously thought

CHICAGO — When the frozen blueberry rolled out of a tube near a 42-inch touch-screen computer in the Lincoln Park Zoo's great ape house, a lowland gorilla named Rollie popped the berry into her mouth, gleefully stomped her feet and let out a celebratory hoot.

Rollie had correctly solved a seven-step number puzzle on the screen, winning a treat and an enthusiastic cheer from a keeper. But her skills are also being noticed outside the confines of the zoo.

Conventional wisdom has it that gorillas are somewhat less intelligent than their great ape cousins. Rollie's surprising success at her morning research routine is challenging those assumptions, suggesting she might in fact be faster on the uptake than chimpanzees and orangutans. A report on her work recently caused a stir at the biennial meeting of the International Primatological Society Congress in Scotland.

"Gorillas have always had a reputation of being a little bit slower-witted than other great apes," said Steve Ross, who supervises cognitive and behavioral research for the zoo's primate research arm, the Lester E. Fisher Center for the Study and Conservation of Apes. "They aren't as dynamic as chimps socially, and they don't show the mechanical cleverness that orangutans display."

Ross admits he subscribed to the theory himself.

"This study can't generalize for all gorillas, but because (Rollie) has been such a quick learner, it suggests that gorillas in general are smarter than we have given them credit for," he said.

Ross' immediate aim in studying primate cognition and intelligence is to devise preference tests that allow animals to "talk" to keepers, expressing what foods they like and don't like and reporting on good and bad features of their habitats. But exploring animal cognition also is a way of looking at the history of human intellect and language, giving insights into how they evolved.

Chimpanzees and orangutans are studied often at primate and medical research laboratories worldwide. But captive gorillas — perhaps too temperamental as adults to be used as research subjects — aren't often kept outside of zoos, so they are far less studied.

Lincoln Park, in fact, is the only place in the world that is doing touch-screen testing with both chimps and gorillas.

"It is exciting to see that (Rollie's) performance is comparable with other great apes," said Tara Stoinski, a Zoo Atlanta primatologist. "What is really exciting is to see this kind of work being done with gorillas because so little research is being done on gorilla cognition."