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Hare suspects that the evolutionary pressures that turned suspicious wolves into outgoing dogs were similar to the ones that turned combative apes into cooperative humans. "Humans are unique. But how did that uniqueness evolve?" asks Hare. "That's where dogs are important."
The first rule for scientists studying dogs is, Don't trust your hunches. Just because a dog looks as if it can count or understand words doesn't mean it can. "We say to owners, Look, you may have intuitions about your dog that are valuable," says Hauser. "But they might be wrong."
Take for instance the kiss a dog gives you when you come home. It looks like love, but it could also be hunger. Wolves also lick one another's mouths, particularly when one wolf returns to the pack. They can use their sense of taste and smell to see if the returnee has caught some prey on its journey. If it did, the licking often prompts it to vomit up some of that kill for the other members of the pack to share. The kiss dogs give us probably evolved from this inspection. "If we happened to spit up whatever we just ate," says Horowitz, "I don't think our dogs would be upset at all."
Horowitz and other scientists are now running experiments to determine what a behavior, like a kiss, really means. In some cases, their research suggests that our pets are manipulating us rather than welling up with human-like feeling. "They could be the ultimate charlatans," says Hauser.
We've all seen guilty dogs slinking away with lowered tails, for example. Horowitz wondered if they behave this way because they truly recognize they've done something wrong, so she devised an experiment. First she observed how dogs behaved when they did something they weren't supposed to do and were scolded by their owners. Then she tricked the owners into believing the dogs had misbehaved when they hadn't. When the humans scolded the dogs, the dogs were just as likely to look guilty, even though they were innocent of any misbehavior. What's at play here, she concluded, is not some inner sense of right and wrong but a learned ability to act submissive when an owner gets angry. "It's a white-flag response," Horowitz says.
While this kind of manipulation may be unsettling to us, it reveals how carefully dogs pay attention to humans and learn from what they observe. That same attentiveness also gives dogs--or at least certain dogs--a skill with words that seems eerily human.
Juliane Kaminski of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, began exploring the verbal gifts of dogs when she saw a television show about a border collie named Rico--an animal that to all appearances could fetch dozens of different objects in response to their names. Kaminski put Rico to a rigorous test and confirmed that the dog could learn names for more than 200 toys, balls and other items. "I think Rico is a highly talented dog," says Kaminski, "but we've also found new dogs that do what Rico did."
That doesn't mean that the dogs understand the words the way we think they do. When they hear "Frisbee," they may think only, Get the Frisbee. Unlike us, they may not be able to recognize that Frisbee is a word for a distinct object that can be combined with other words to create sentences like "Run away from the Frisbee."