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As humans became better at hunting, they left scraps around their gathering spots. When they departed, the ancestors of dogs could move in. At first, when humans and wolves came into contact, many of the animals ran away. Others lashed out and were killed. Only the affable animals had the temperament to become camp followers, and their new supply of food let them produce affable puppies. "They selected themselves," says Horowitz.
Once dogs became comfortable in our company, humans began to speed up dogs' social evolution. They may have started by giving extra food to helpful dogs--ones that barked to warn of danger, say. Dogs that paid close attention to humans got more rewards and eventually became partners with humans, helping with hunts or herding other animals. Along the way, the dogs' social intelligence became eerily like ours, and not just in their ability to follow a pointed finger. Indeed, they even started to make very human mistakes.
A team led by cognitive scientist Josef Topál of the Research Institute for Psychology in Hungary recently ran an experiment to study how 10-month-old babies pay attention to people. The scientists put a toy under one of two cups and then let the children choose which cup to pick up. The children, of course, picked the right cup--no surprise since they saw the toy being hidden. Topál and his colleagues repeated the trial several times, always hiding the toy under the same cup, until finally they hid it under the other one. Despite the evidence of their eyes, the kids picked the original cup--the one that had hidden the toy before but did not now.
To investigate why the kids made this counterintuitive mistake, the scientists rigged the cups to wires and then lowered them over the toy. Without the distraction of a human being, the babies were far more likely to pick the right cup. Small children, it seems, are hardwired to pay such close attention to people that they disregard their other observations. Topál and his colleagues ran the same experiment on dogs--and the results were the same. When they administered the test to wolves, however, the animals did not make the mistake the babies and dogs did. They relied on their own observations rather than focusing on a human.
One question the research of Topál, Hare and others raises is why chimpanzees--who are in most ways much smarter than dogs--lack the ability to read gestures. Hare believes that the chimps' poor performance is one more piece of proof that the talent is rooted not in raw intelligence but in personality. Our ape cousins are simply too distracted by their aggression and competitiveness to fathom gestures easily. Chimps can cooperate to get food that they can't get on their own, but if there's the slightest chance for them to fight over it, they will. For humans to evolve as we did, Hare says, "We had to not get freaked out about sharing."
Deeper understanding of the mind of the dog will come with more testing, and Hare and other researchers are planning it--on a grand scale. They're designing new experiments to compare different breeds and to search for genes that were transformed as the animals' social intelligence evolved. Plenty of dog owners are signing up for the studies Hare will be launching this fall. "We'd be happy with thousands," he says.
The biggest challenge to the new experiments, Hare says, will be not the giant pack of dogs he'll be studying but their anxious owners. "When a puppy does badly, people get upset," says Hare. "You have to emphasize that this is not the SATs."
Perhaps that's the most telling sign of just how evolved dogs are. They have us very well trained.