But how had this understanding come about? Was it a result of humans choosing dogs that displayed the ability, or was it simply a side effect of the domestication package, as Wrangham suggested?
In Siberia, Hare found the foxes to be "absolutely adorable. They just want to jump in your arms." (But they have a musky stench, are hyperactive and would make "terrible pets," says Hare.) They also performed brilliantly on tests to understand human gestures, while a control group of normal foxes did not. "The fearless foxes hadn't been selected to be smarter," notes Hare. "They were selected for ‘niceness,' for being able to be handled, and that seems to have been the case with dogs too."
Thus, to get a smart dog—a dog that knows how to pull a sled or herd sheep or listen to your commands—you select the ones that aren't afraid or aggressive, that is, those that have evolved to keep their original wolf caution at bay. When fear is not a factor, human and dog can live and work together. "It really has nothing to do with what we think of as major cognitive abilities," Hare says. "It's far more simple and starts with emotional restraint."
Hare and others have speculated that social and emotional skills led to the evolution of intelligence in the great apes and humans. Since the 1970s, some scientists have claimed that animals are more likely to survive and reproduce if they are able to read social cues—to keep track of what other group members are up to and to deceive them if necessary. But Hare focuses on a slightly different type of social intelligence, the ability to work with others, regardless of whether they are strangers or rank lower in the social hierarchy. Hare's quest to find the primate roots of our social tolerance—and hence, according to him, our intelligence—brought him, finally, to living his original dream.
These days Hare, 31, studies chimpanzees and bonobos in sanctuaries in Uganda, the Congo Republic and Congo, when not at his home base at the Max Planck Institute in Leipzig, Germany. He has dozens of experiments underway at the sanctuaries, investigating the apes' social behaviors and how they affect the animals' ability to solve problems.
From these studies, Hare has come to have a better understanding of why chimpanzees fail seemingly simple tests. For instance, one experiment requires two chimps to pull on opposite ends of a rope at the same time. When they do, the rope moves a board and brings some tasty food within reach. "They all understand the problem, and they know what they need to do to solve it," he says. But only some chimpanzees succeed: the ones that—when their food bowls are placed close together—sit next to each other and feed peacefully. In most cases, either a chimp of lower rank won't eat in the presence of its superior, or the higher-ranking one attacks the other. These pairs fail to get the food on the board "because of social tensions. They can't get beyond that to work together," Hare says. "Only those chimps that eat together are able to cooperate to solve this task."
But bonobos, close relatives of chimps, relieve social tensions quickly and enthusiastically: when two or more bonobos, of either gender, encounter each other, they have a quick bout of sex. Then they settle down and work on the problem together. Bonobos ace Hare's tests.
There's a lesson here for us, Hare says. "It's true humans have bigger brains and language, and so forth. But we would not have evolved the kind of intelligence we have—the kind that allows us to use our brains together, to build things, to be mentally flexible—if we hadn't had a shift in temperament." That is, we had to become more like bonobos and less like chimps, which are high-strung, fearful of strangers and generally intolerant of any chimp lower on the social hierarchy. "We had to lose all those traits in order to become who we are," he adds. Controlling one's fears, paying attention to others, finding joy in working with others—that's the path to intelligence, he says, whether for dogs, apes or humans.
Virginia Morell has written about the Zuni, wildebeest migrations and the repair of the ozone hole for Smithsonian.