Horses may join dogs as human emotional companions, study finds

Researchers at the University of Tours found that horses exposed to sweat from fearful humans showed higher heart rates and more hesitant, startled behaviour than when exposed to neutral or happy scents.

A French research team report that horses can detect human fear through smell and respond with measurable behavioural and physiological changes. Scientists collected sweat samples from people who watched frightening or happy videos and presented those samples to horses while recording heart rate and behaviour. Tests included suddenness reactions, responses to unfamiliar objects and interactions with handlers. The work follows prior studies showing animals, including dogs, can perceive human emotional chemosignals. Key findings: - Sweat samples were gathered on cotton pads from people viewing fearful or happy videos and placed near the nostrils of 43 female horses, with clean pads used as controls. - Horses exposed to scents from fearful humans showed higher heart rates, were more easily startled, stared longer at unfamiliar objects and were less likely to approach or touch handlers than when exposed to happy or neutral scents. - The researchers link these responses to changes in volatile organic compounds in fear-related sweat, such as aldehydes, ketones, fatty acids and steroid-related molecules. - The team notes that horses’ sensitivity to human chemosignals may be tied to survival instincts rather than the domestication pathway suggested for dogs, and that emotional signals can cross species boundaries. - The article also references earlier research reporting similarities between horses and humans in skin pain-detection structures. Summary: The study indicates that horses can perceive chemical signatures of human fear and adjust their behaviour and physiology accordingly. These results suggest chemosignals may play a role in interactions between humans and domestic mammals. Undetermined at this time.