What’s bred in the bone will out in the dog: study
On the whole, dogs are smart. They get it. Point to the hidden treat, the dog can find it. It seems normal, but the fact that dogs have an instinct to understand human gesture is also deeply mysterious, as new research shows.
Dogs evolved from domesticated wolves. That much is known. But they did so while living with humans, who imposed an evolutionary selection pressure towards dogs that get along with people.
Wolves are social and communicative when they need to be, such as hunting in packs, but even if they are raised by humans, wolves just do not seem to get human gesture in the same way dogs do.
Dogs are more skilled with human gestures than even our closest genetic relative, chimpanzees. Great apes perform poorly with novel and arbitrary gestures. They can learn pointing and other gestures with practice, but not intuitively from an early age like dogs do.
Even without intense training, dogs share a “communicative flexibility” with human beings, according to a new research study. They can understand and use human gestures, which says nearly as much about humans as it does about dogs.
“It’s not only about dogs,” said Hannah Salomons, lead author on the paper in Current Biology and a PHD candidate in the Department of Evolutionary Anthropology at Duke University in North Carolina. Gesture comprehension is an important part of human development that precedes the ability to use and understand language. It has some deep evolutionary roots.
Dogs were certainly selected for friendly behaviour, from among wolves in the orbit of early human settlement, probably as scavengers, most of whom would have reacted to humans with fear and flight.
This latest research tests the idea that selection for friendly temper leads to early emerging co-operating skill, evidenced by gesture use.
One theory is that domestication changed the way dogs mature socially by selecting for attraction to humans. Dogs became more flexible in using inherited skills to co-operatively communicate with a new social partner. The effect, on this view, is that modern dogs express these unusual skills as the youngest puppies, even without intensive exposure to humans, but modern wolves, who were never social with humans, do not.
One recent study at the University of Arizona showed that nearly half of the variation in dogs’ abilities to follow human pointing was accounted for by genetic factors. By its very DNA, on this theory, canis familiaris really is Homo sapiens’ best friend.
An alternative theory is that dogs inherited these skills from wolves, their ancestor. Again, there is evidence. Wolves are obviously social, hunting in packs. Some adult wolves can learn human gestures. But even if they are raised by humans, wolf pups rarely show spontaneous use of gestures like dogs do.
To test this, Salomons ran an experiment with 44 dog puppies and 37 wolf puppies between five and 18 weeks old. All the dogs were retrievers bred and raised for assistance work at Canine Companions for Independence in Santa Rosa, Calif., and at this early stage received little human contact, only during routine caretaking tasks.
The wolves were first or second generation bred in captivity at a rescue centre in Minnesota and received human care such as feeding and co-sleeping for either 24 hours or 12 hours a day.
The pups were made to perform tasks to test their temperament and cognition, such as whether they would approach a familiar or unfamiliar human to retrieve a toy, and their memory for where they had seen food hidden.
The key task was a variation on this treat-finding problem in which the puppy would know food has been hidden in a bowl, but could not see which one, and had to find it based on a human’s gesture. The experimenter would either point with a straight arm and look with a constant gaze, or place a marker, a wooden block.
A control experiment did the same task with no pointing to account for the effect of smell, which was negligible.
Both dogs and wolves performed better than chance, but dog puppies chose correctly 78 per cent of the time for both pointing and the marker, while wolves chose correctly 62 per cent of the time for pointing and 57 per cent for the marker.
Even though the wolf puppies had much more exposure to humans, the dog puppies were better at understanding them. Salomons said dog puppies have something in them that makes them more likely to interpret a human gesture as attractive. On the other hand, she said, it does not seem to occur to the wolf puppies that a human might be trying to help them.
“Our results support the predictions of the domestication hypothesis,” reads the paper. “Dog but not wolf puppies are attracted to humans and show early emerging skills for reading human gestures, even though the wolf puppies received more intense human socialization. Dog puppies’ odds of using each human gesture correctly were more than twice those of wolf puppies. Half of the dog puppies were successful at the individual level, whereas no wolf puppy was. Dog puppies also spontaneously used both gestures on their first test trial and there was no evidence for increasing success within test sessions or in older puppies.”
Asked by the National Post about cats, Salomons said they evolved from solitary hunters, without even the social character of wolves. If they understand human gestures, or indeed care about them, it is probably not in the same way as dogs do, she said.