Horses can smell fear in humans, according to researchers who found that the animals reacted more strongly to body odour from people who had watched horror films. The study, published in the journal Plos One, suggests that fear can be transmitted between species through chemical signals in sweat.
In a series of experiments, scientists at the University of Tours in France collected sweat samples from volunteers who watched either a horror movie, such as Sinister, or joyful scenes from films like Singin’ in the Rain. Cotton pads worn in the armpits were then stapled to the muzzles of horses to expose them to the odours.
The horses exposed to sweat from frightened people showed greater startle responses when an umbrella suddenly opened, had higher peak heart rates, and spent less time approaching or touching their handlers compared with when they smelled sweat from happy individuals. However, levels of the stress hormone cortisol did not differ between the two conditions.
Dr Léa Lansade, who led the research, said: “This study shows how closely connected animals and humans are. Unconsciously, we can transmit our emotions to animals, with quite important effects on their own emotions in return.” The findings have implications for riders, trainers and anyone working with horses.
Dr Plotine Jardat, first author of the study, advised: “Arriving relaxed and in a positive mood can foster a better interaction with the horse, whereas if you are afraid yourself, the horse can feel afraid in response and react more strongly to a potentially scary situation.”
Professor Biagio D’Aniello of the University of Naples Federico II, who has shown similar effects in dogs and horses, commented: “The findings add to growing evidence that emotional signals can cross species boundaries, with horses reacting to human fear via smell. This raises intriguing questions about how human stress or calmness might shape everyday human-horse interactions.”
