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Millennia of Human Contact Linked to Unusual Canine Cognition
Cambridge, Mass. - February 13, 2004 - Living with humans for hundreds of generations has altered the cognitive abilities of domesticated dogs, according to new research by Harvard University anthropologist Brian Hare. He will report these findings in Seattle this week at the annual meeting of the American Association for the Advancement of Science.
Our new work provides direct evidence that dogs' lengthy contact with humans has served as a selection factor, leading to distinct evolutionary changes," says Hare, who recently completed his Ph.D. in anthropology in Harvard's Faculty of Arts and Sciences. "This is the first demonstration that humans play an ongoing role in the evolution of canine cognition."
Hare has shown previously that domesticated dogs are far more skillful at reading human communicative signals -- such as glances or pointing -- than either a close human relative, the chimpanzee, or a close dog relative, the wolf.
Hare's latest research involved New Guinea Singing Dogs, a subspecies that shows strong indications of domestication at some time in the past but now exists as feral, reclusive individuals in the highlands of New Guinea. These dogs, related to dingoes, have gone without significant human contact for at least the past 6,000 years, and little is known about their behavior in the wild.
When New Guinea Singing Dogs watched a human place food under one of two cups and then gesture toward the cup hiding the food, few approached the cup concealing the food more than half the time, as would be expected by chance. By comparison, among domesticated dogs with an unbroken history of human contact, Hare found that all individuals were able to interpret the same human gestures to locate the food.
"Domesticated dogs are strikingly similar to young children in their ability to perceive and interpret human gestures, and they show this propensity from a few weeks of age," Hare says. "Given our results with the New Guinea Singing Dogs, it now appears that ongoing human contact during dog domestication caused the unusual ability for reading human communicative signals to evolve in modern dog breeds."
After first realizing several years ago that dogs possessed this unusual capacity to interpret human gestures, Hare developed several possible explanations. One hypothesis, that dogs had inherited this ability from wolves, was not supported by Hare's subsequent finding that wolves are not skilled at reading human signals. Another theory, which held that individual dogs learn to interpret human cues over the course of living with people, was compromised by the finding that puppies reared with and without human contact showed equal proficiency in these skills.
Hare's research is supported by the New Guinea Singing Dog Conservation Society. He was joined in this research by Harvard undergraduate Victoria Wobber and by Janice Koler-Matznik, director of the New Guinea Singing Dog Conservation Society.
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