The Primate Research Institute sits on a hill in Inuyama, Japan, a quiet city that rambles along the Kiso River and is renowned for a 16th-century castle. Handsome homes with traditional curved roofs line Inuyama’s winding streets. The primate facility consists mostly of drab, institutional boxes from the 1960s, but it has one stunning architectural feature: an outdoor facility that includes a five-story-high climbing tower for the 14 chimpanzees currently in residence. Chimps frequently scamper to the top of the tower and take in the view; they tightrope across wires connecting different parts of the tower and chase each other in battle and play.
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When I walked out onto a balcony overlooking the tower with Tetsuro Matsuzawa, the head of the institute, the chimpanzees spotted us immediately and began to chatter.
“Woo-ooo-woo-ooo-WOO-ooo-WOOOOOOO!” Matsuzawa sang out, voicing a chimp call known as a pant-hoot.
A half-dozen chimps yelled back.
“I am sort of a member of the community,” he told me. “When I pant-hoot, they have to reply because Matsuzawa is coming.”
Matsuzawa and the dozen scientists and graduate students who work with him are peering into the minds of our closest relatives, whose common ancestor with humans lived some six million years ago, to understand what separates them from us. He and his co-workers probe how chimpanzees remember, learn numbers, perceive and categorize objects and match voices with faces. It’s a tricky business that requires intimate relationships with the animals as well as cleverly designed studies to test the range and limitations of the chimpanzees’ cognition.
To move them from the outdoor structure to the laboratories inside, researchers lead the animals along a network of catwalks. As I ambled under the catwalks, the chimps going into various laboratories for the morning’s experiments spit on me repeatedly—the standard greeting offered to unfamiliar humans.
The lab rooms are about the size of a studio apartment, with humans separated from chimpanzees by Plexiglas walls. Following Japanese tradition, I removed my shoes, put on slippers, and took a seat with Matsuzawa and his team of researchers. The human side of the room was crowded with computer monitors, TVs, video cameras, food dishes and machines that dispense treats to the chimps. The chimp enclosures, which look like oversize soundproof booths from an old TV game show, were empty, but slots cut into the Plexiglas allowed the chimps to access touch-screen computers.
Matsuzawa’s star research subject is a chimp named Ai, which means “love” in Japanese. Ai arrived at the institute, part of Kyoto University, in 1977, when she was 1 year old and Matsuzawa was 27. Matsuzawa had done some basic studies with rats and monkeys, but he knew little about chimpanzees. He was given the job of training her. Years later, he wrote an account of their first meeting: “When I looked into this chimpanzee’s eyes, she looked back into mine. This amazed me—the monkeys I had known and worked with never looked into my eyes.” Monkeys, separated from humans by more than 20 million years, differ from chimpanzees and other apes in many ways, including having tails and relatively limited mental capacities. “I had simply thought that chimpanzees would be big black monkeys,” Matsuzawa wrote. “This, however, was no monkey. It was something mysterious.”
Now, one of the researchers pushed a button, gates clanged and Ai entered the enclosure. Her son Ayumu (which means “walk”) went into an enclosure next-door, which was connected to his mother’s room by a partition that could be opened and closed. The institute makes a point of studying mothers and their children together, following the procedures under which researchers conduct developmental experiments with human children. Ai sauntered over to a computer screen.