The first time Fu Manchu broke out, zookeepers chalked it up to human error. On a balmy day, the orangutans at the Omaha Zoo had been playing in their big outdoor enclosure. Not long thereafter, shocked keepers looked up and saw Fu and his family hanging out in some trees near the elephant barn. Later investigation revealed that the door that connects the furnace room to the orangutan enclosure was open. Head keeper Jerry Stones chewed out his staff, and the incident was forgotten. But the next time the weather was nice, Fu Manchu escaped again. Fuming, Stones recalls, "I was getting ready to fire someone."

The next nice day, alerted by keepers desperate to keep their jobs, Stones finally managed to catch Fu Manchu in the act. First, the young ape climbed down some air-vent louvers into a dry moat. Then, taking hold of the bottom of the furnace door, he used brute force to pull it back just far enough to slide a wire into the gap, slip a latch and pop the door open. The next day, Stones noticed something shiny sticking out of Fu's mouth. It was the wire lock pick, bent to fit between his lip and gum and stowed there between escapes.

Fu Manchu's jailbreaks made headlines in 1968, but his clever tricks didn't make a big impression on the scientists who specialize in looking for signs of higher mental processes in animals. At the time, much of the action in animal intelligence was focused on efforts to teach apes to use human languages. No researcher cared much about ape escape artists.

And neither did I. In 1970, I began following studies of animal intelligence, particularly the early reports of chimpanzees who learned how to use human words. The big breakthrough in these experiments came when two psychologists, R. Allen and Beatrice Gardner, realized their chimps were having trouble forming wordlike sounds and decided to teach a young female named Washoe sign language instead. Washoe eventually learned more than 130 words from the language of the deaf called American Sign Language.

Washoe's success spurred more language studies and created such ape celebrities as Koko the gorilla and Chantek the orangutan. The work also set off a fierce debate in scientific circles about the nature of animal intelligence--one that continues to this day. Indeed, it has been easier to defeat communism than to get scientists to agree on what Washoe meant three decades ago when she saw a swan on a pond and made the signs for "water bird." Was she inventing a phrase to describe waterfowl, or merely generating signs vaguely associated with the scene in front of her?

Over the years I have written several articles and two books on animal-intelligence experiments and the controversy that surrounds them. I have witnessed at close range the problems scientists encounter when they try to examine phenomena as elusive as language and idea formation. Do animals really have thoughts, what we call consciousness? The very question offends some philosophers and scientists, since it cuts so close to what separates men from beasts. Yet, notes Harvard's Donald Griffin, to rule out the study of animal consciousness handicaps our understanding of other species. "If consciousness is important to us and it exists in other creatures," says Griffin, "then it is probably important to them."

Frustrated with what seemed like an endless and barren ideological debate, I began to wonder whether there might be better windows on animal minds than experiments designed to teach them human signs and symbols. When I heard about Fu Manchu, I realized what to me now seems obvious: if animals can think, they will probably do their best thinking when it serves their purposes, not when some scientist asks them to.

And so I started exploring the world of animal intelligence from the other side. I started talking to people who deal with animals professionally: veterinarians, animal researchers, zookeepers--people like Jerry Stones. Most are not studying animal intelligence per se, but they encounter it, and the lack of it, every day.

Get a bunch of keepers together and they will start telling stories about how their charges try to outsmart, beguile or otherwise astonish humans. They tell stories about animals that hoodwink or manipulate their keepers, stories about wheeling and dealing, stories of understanding and trust across the vast gulf that separates different species. And, if the keepers have had a few drinks, they will tell stories about escape.

Each of these narratives reveals another facet of what I have become convinced is a new window on animal intelligence: the kind of mental feats they perform when dealing with captivity and the dominant species on the planet--humanity.

What Do You Want for That Banana? captive animals often become students of the humans who control their lives. The great apes in particular are alert to situations that might temporarily give them the upper hand--for example, when something useful or valuable rolls into their exhibit or is left behind. The more worldly animals recognize the concept of value as meaning "something I have that you want," and they are not above exploiting such opportunities for all they are worth.