What the experiment revealed
An ability that predates domestication?
Dogs are capable of picking up on chemical signals associated with human emotions; however, as scientists have discovered, this ability may be far older than the process of domestication. In an experiment, wolves raised in captivity alongside humans responded to the scent of human fear in much the same way that dogs do.
Wolves can also sense human fear through scent—and they react to it
Dogs can perceive our emotions through more than just facial expressions or tone of voice; they also detect chemical signals released by the human body. Previous research has shown that the sweat of a frightened person can alter a dog’s behavior and even increase its heart rate. Since this reaction is also observed in puppies, scientists hypothesize that it may be innate rather than something acquired through training.
But when exactly did this ability emerge—was it present in the wild ancestors of dogs, or did it develop during the process of domestication? To find out, researchers compared how dogs and wolves react to the scent of human fear.
What the experiment revealed
In a new study published in the journal Animal Cognition, researchers collected sweat samples from ten women after they watched two different types of videos: a relaxing nature film and a horror movie. These samples were then presented to 11 dogs and eight wolves. All the animals had been born and raised in captivity and were socialized with humans.
The subjects were presented with pairs of samples—one containing chemical signals associated with fear, and the other without. Neither the dogs nor the wolves showed a clear preference for either scent. However, when presented with a sample containing “fear-related” sweat, the animals behaved in a similar way: they spent less time near it and looked more frequently at the human accompanying them.
An ability that predates domestication?
The similarity in these reactions suggests that sensitivity to human chemical signals may have emerged in canids even before humans began domesticating dogs. In other words, domestication might not have created this ability from scratch, but rather enhanced or preserved a trait that already existed.
Nevertheless, it is too early to draw conclusions about the behavior of wild wolves. All the subjects in the study were raised in contact with humans, so it remains unknown whether animals that had never lived alongside humans would respond in the same way.
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