Scientific American presents The Dog Trainer by Quick & Dirty Tips. Scientific American and Quick & Dirty Tips are both Macmillan companies.

Can dogs tell which people are generous and which ones are stingy? I can hear you now: “Of course they can – why else has Zippy spent every family dinner gazing wistfully up at Aunt Trudy ever since the first time she accidentally-on-purpose dropped a piece of roast in front of him?”

But it’s one thing to learn that someone who shares their food with you once may do it again. An animal needs a different set of skills to figure out whether a complete stranger is generous, just by watching how she acts toward yet another stranger. In testing whether dogs can judge a person’s generosity this way, we can learn something about their ability to read human social behavior.

The Experiment
“Eavesdropping” – how animals observe and take advantage of other animals’ behavior – is a hot scientific topic. Animals of all kinds eavesdrop in various ways. They observe when others have used up all the resources in a particular spot; they notice where competitors have stored food, and then they steal it; they flee when they hear alarm calls from a different species. That last kind of eavesdropping, in which animals of one species “read” the social signals passed between members of another species, is especially remarkable. We know that dogs are sensitive to human body language when it’s directed toward them; can they also learn from the signals we humans pass to each other?

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