Dogs are born with an innate ability to read human gestures that is not apparent in their closest relative, wolves.
Even when wolf puppies are carefully raised by humans and hand-fed for weeks, researchers say the animals act skittish around strangers, make little eye contact, and don't respond to basic gestures.
In a round of hidden treat experiments, for instance, none of the 26 wolves in the study was able to consistently figure out what it meant when a human in the room pointed their finger, or indicated a treat's location with an object.
On the other hand, 17 out of 31 retriever puppies, who were raised with far less human contact, had a better idea what the finger was trying to say. More than half the group consistently went to the bowl being pointed at. Some even got it right on the first round.
"Dogs are born with this innate ability to understand that we're communicating with them and we're trying to cooperate with them," says Hannah Salomons, who studies cognition at Duke University.
Only last month, a similar study found up to 40 percent of a puppy's ability to communicate with us is genetic, not learned.
The new findings among wolves provide more evidence suggesting that human domestication of dogs has sculpted their genes in ways that suit our purposes.
Our domestication of dogs is thought to have begun at least 12,000 years ago, and in all that time, we've selected the traits seen in wild wolves we deem most advantageous. In short: we have sculpted our perfect companion out of the wilderness.
"This study really solidifies the evidence that the social genius of dogs is a product of domestication," says evolutionary anthropologist Brian Hare from Duke University.
That's not to say some human communication can't be learned. Dogs can become more skilled at learning human gestures as they age, in the same way that wolf pups can learn to trust humans over time.
Dogs are just far less fearful of our species from an early age.
"With the dog puppies we worked with, if you walk into their enclosure they gather around and want to climb on you and lick your face, whereas most of the wolf puppies run to the corner and hide," says Salomons.
In fact, in the study, which involved 37 wolves and 44 dog pups in total, researchers found dog puppies were five times more likely to approach a familiar caretaker in a room and 30 times more likely to approach a stranger compared to the wolf pups.
During the experiments, the dogs also looked to humans in the room more often than wolves, making eye contact when they couldn't figure out certain parts of the experiments.
The stark differences in behavior hint at a long history of evolutionary changes. Over the course of thousands of years, it seems, we have taken the shy wolf and turned it into an affectionate companion.
"Before this selection, any human-wolf interaction was constrained by the flight response of wolves," the researchers propose.
"Once attraction replaced fear, inherited social skills were applied toward humans in a new way and early in development."
The study was published in Current Biology.