Photograph by Alex Saberi, Nat Geo Image Collection
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A stray dog rests in Brazil's Chapada Diamantina National Park. There are up to 300 million stray dogs worldwide.

Photograph by Alex Saberi, Nat Geo Image Collection

Stray dogs have the natural ability to understand human gestures

The research could lead to a more peaceful co-existence between free-roaming canines—which number hundreds of millions worldwide—and people.

Humans domesticated dogs, and over our 15,000-year relationship, we’ve bred canines to be friendly and eager companions—as well as skilled at interpreting our emotions.

Now, a new study reveals even stray dogs—animals that have never lived with people—can still understand our gestures.

Up to 300 million stray dogs roam the planet, with about 30 million in India alone. These free-ranging canines often come into conflict with people, and, particularly in India, pose a public health risk as carriers of rabies, a fatal virus that kills up to 20,000 people a year in India, most of them children, according to the World Health Organization.

This has made the management of stray dogs a polarizing subject, with some people killing the animals inhumanely, says Anindita Bhadra, animal behaviorist at the Indian Institute of Science Education and Research Kolkata. Stray dogs, she adds, are never sure whether people want to feed and pet them—or hurt them.

That's why learning more about stray dogs and their behavior is crucial to resolving problems with people, says Bhadra, who has studied the animals for a decade. (Read about the many human signals dogs can understand.)

In recent experiments, she discovered that most stray dogs knew where to look when a human was pointing to an object, suggesting their ability to read humans is innate.

The study’s findings could help educate adults and children—who are often bitten and infected with rabies while sharing food with stray dogs—how to interact with them, leading to “a more peaceful co-existence,” she says. (Take National Geographic's dog quiz.)

Getting to the point

In the study, published January 17 in the journal Frontiers in Psychology, Bhadra and colleagues approached 160 solitary stray dogs in several Indian cities. An experimenter placed two covered bowls on the ground near them, one containing raw chicken, the other empty with just the scent of food. A second experimenter, who didn’t know which bowl was which, would then stand and point at one of the bowls, sometimes for just one second, sometimes for the length of the experiment. The hands of the second experimenter were never near the bowls.

About half of the dogs wouldn’t come close to the experimenters; many appeared anxious and had likely had negative encounters with people, Bhadra says. (Related: how your dog knows how you feel.)

Evolution Of Dogs

Of the half that did approach, about 80 percent went to the bowl to which the second experimenter had pointed, meaning they understood the human’s gesture. If the dogs discovered that bowl was empty, they were less likely to follow the pointing cue again.

In previous studies, experimenters had been much closer to the bowls. Having the person farther away allows the canine to “judge what the humans intention is and then make a decision,” Bhadra says, as well as process new information based on whether following that cue was rewarding or not.

Overall, the study suggests that untrained dogs can relate to humans, despite likely having had traumatic experiences with them.

“This is more evidence that free-ranging dogs are just as good as any other dog at using basic human gestures, and that free-ranging dogs are as smart as people often imagine,” says Brian Hare, founder and director of the Duke Canine Cognition Center at Duke University, via email. (Read how dogs changed humans over time, too.)

Understanding stray dogs

Stray dogs are also not a recent phenomenon. The ancient Indian text The Vedas advises giving leftovers to scavengers, including stray dogs, as part of being a good householder.

While they lead tougher lives than those of house pets, strays have nonetheless adapted to us, "through the Industrial Revolution to highways, everything," Bhadra says. (Learn how dogs know the meaning of a human smile.)

Such adaptability and resilience, as well as psychological sophistication, means free-roaming canines are not much different than any other dog, adds Hare—"and that they deserve our respect."