Ayumu the chimpanzee didn’t hesitate. Shown the numbers one through nine on a computer touch screen, he tapped the numerals in order, even after two through eight had disappeared behind white squares within a fraction of a second. The human audience watching a video of this performance began to murmur as they tried and failed to keep up with the fast-fingered chimp.
“Don’t worry, no one can do it,” Kyoto University researcher Tetsuro Matsuzawa reassured them with a laugh. “It’s impossible for you.”
New studies of the brainpower of our closest primate cousins reveal how chimpanzee cognition mirrors—and in some cases surpasses—the capabilities of the human brain, researchers said at the 2013 AAAS Annual Meeting.
At the same time, the knowledge that chimpanzee minds are much like ours has led to some darker discoveries, such as occurrence of depression, post-traumatic stress disorder and anxiety disorders in captive great apes. Faced with a growing understanding that chimpanzee brains operate and break down much like human brains, the scientific community is also taking a closer look at studies involving these animals.
The new research, said Neal Barnard, president of the advocacy group Physicians Committee for Responsible Medicine, is “leading us to a seismic change in our relationship with our research subjects, who used to be resources and are now living beings showing psychopathology and in some cases outstripping our cognitive capacities.”
Demonstrations like the Ayumu video, Matsuzawa said, can convince people that chimpanzees are more capable than humans on some cognitive tasks—a finding that has been difficult for some humans to accept.It would be extremely rare to find a human with the “extraordinary working memory” of a chimpanzee, he said, but the reasons for this may stem from a tradeoff between memory and language. Human language makes memory portable over time and space, making it less essential for us to hold items in mind at a precise moment.
“Chimps are living in the world of here and now,” Matsuzawa said. “We are living in the world, thinking about the past, thinking about the future, trying to understand the meaning of what we see, and bringing the information back to friends and families and colleagues to share the experience.”
At the same time, chimpanzees and bonobos seem to engage in some of the same kinds of decision making, risk management and problem solving long considered “human-only” behavior, said Harvard University researcher Victoria Wobber. She studies chimpanzees and bonobos at African ape sanctuaries set up to save great apes orphaned by the bushmeat trade.
Several studies show, for instance, that chimpanzees know when they need a partner to solve a task, and they recruit likely helpers. And, like any human who has ever worked on a team project, the apes know how to “track who in their environment is the better collaborator, and they actually choose those individuals as collaborative partners,” she said.
Tetsuro Matsuzawa working with chimpanzees. | Credit: Primate Research Institute, Kyoto University
Wobber also has found cooperative and cognitive differences between chimpanzees and the famously physically affectionate bonobos. “Bonobos may be able to better express their cooperative capacities,” she said, “because they are more tolerant of one another.”
These discoveries and many others have contributed to a building movement to stop using chimpanzees as research subjects, or to at least put new ethical guidelines in place for the animals’ participation, said Barnard, who also serves as an associate professor of medicine at George Washington University.
He cited an influential 2011 Institute of Medicine report concluding that chimpanzees are not essential to most ongoing biomedical research, and subsequent efforts by the U.S. National Institutes of Health to retire its research chimpanzees.
Some researchers have suggested that veterans of this research, who show signs of human-like post-traumatic stress disorder or depression, should be treated like human psychiatric patients, perhaps even with psychiatric drugs. It’s a controversial notion, Barnard acknowledged, saying there needs to be “some kind of behavioral method of assessment to see if this actually can be helpful.”