Humans and dogs have been best friends for perhaps 30,000 years, according to anthropological and DNA evidence. So it would make sense that dogs are particularly suited to express human emotions. They have evolved to read verbal and visual cues from their owners, and previous studies have shown that with their strong sense of smell, they can even detect the scent of stress in human sweat. Now researchers have found that not only can dogs smell stress – in this case it is represented by high levels of the hormone cortisol – they also react to it emotionally.
For a new study, published on Monday in Scientific reports, scientists at the University of Bristol in England recruited 18 dogs of different breeds, along with their owners. Eleven volunteers who were not familiar with the dogs were put through a stress test involving public speaking and mathematics while samples of their armpit sweat were collected on a pieces of cloth. Next, participants performed an exercise that involved watching a natural video on a bean bag chair under dim lighting, after which fresh sweat samples were taken. . Sweat samples from three of these volunteers were used in the study.
Participating canines were placed in groups of three and sniffed sweat samples from one of the three volunteers. Before doing so, the dogs were trained to know that the food bowl in one location contained tasty food and that the bowl in the other location did not. During the test, bowls that were not treated were sometimes placed in one of the three “ambiguous” locations. In another test session, when dogs smelled a sample from a stressed volunteer, compared to a cloth odor without the sample, they were less likely to approach the bowl in an ambiguous location, suggesting that they think this bowl didn’t do that. it has fun. Previous studies have shown that the anticipation of negative consequences shows low mood in dogs.
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The results suggest that when dogs are around stressful people, they are less optimistic about uncertain situations, while being around people with soothing scents does not have this effect. says Zoe Parr-Cortes, lead author of the study and Ph.D. student at the Bristol Veterinary School at the University of Bristol. “Over thousands of years, dogs have learned to live with us, and a lot of their evolution has been around us,” he says. “Being able to hear stress from another pack member would be useful because it alerted them to a threat that another pack member had noticed.”
The fact that the scent came from a person unfamiliar with dogs speaks to the importance of smell to animals and the way it affects emotions in such active situations, says Katherine A. Houpt, senior professor in behavioral medicine at Cornell. University College of Veterinary Medicine. Houpt, who was not involved in the new study, suggests that the scent of stress may have reduced the dogs’ hunger because it is known to affect appetite. “It may not be that it changes their decisions but more that it changes their food intentions,” he says. “It makes sense because when you’re stressed, you’re not interested in that candy.”
This research, Houpt adds, shows that dogs have empathy based on smell in addition to pictures and words. And when you’re stressed, that can translate into behaviors your dog isn’t showing, she says. Furthermore, it leaves us wondering if stress affects animals under the severe burden of their owner. “If dogs respond to mild stress like this, I’d be interested to see how they respond to something serious like an impending storm, losing a job or failing an exam,” says Houpt. “One would expect a dog to be more responsive to a real threat.”
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