In 1995, Brian Hare began to wonder what his dog Oreo was thinking.

At the time, he was a sophomore at Emory University, where he was studying animal psychology with Michael Tomasello. Dr. Tomasello was comparing the social intelligence of humans and other animals.

Humans, it was known at the time, are exquisitely sensitive to signals from other humans. We use that information to solve problems that we might struggle to figure out on our own.

Dr. Tomasello discovered that chimpanzees, our closest living relatives, typically fail to notice much of this social information. Pointing to the location of a hidden banana will usually not help a chimp find the banana, for example. Perhaps the pointing test revealed something important about how the human mind evolved.

But Mr. Hare had his doubts. “I think my dog can do that,” he declared.

To persuade his mentor, he videotaped Oreo chasing after tennis balls. And indeed, when he pointed left or right, off the dog would run, in the indicated direction, to find a ball.