For centuries, dogs have been lauded as humanity's most emotionally attuned companions, famously able to sense our moods. However, pioneering new research reveals they are not alone in this remarkable ability. A scientific study has discovered that horses possess the same capacity to detect human emotions, specifically by smelling our fear.
The Science of Sensing Fear
Researchers from the University of Tours in France conducted a meticulous experiment to test whether horses could pick up on the chemical signals, or chemosignals, humans release when afraid. The team collected scent samples by placing cotton pads in the armpits of human volunteers as they watched either frightening or happy videos. These pads, now carrying the distinct odour signatures of different emotional states, were then presented to 43 female horses.
The results were striking. Horses exposed to the scent of frightened humans displayed significantly heightened reactivity. Their heart rates elevated, they became more easily startled, and they showed greater hesitation in approaching handlers. In contrast, horses presented with scents from happy humans or clean pads remained noticeably calmer.
An Evolutionary Survival Tool
While dogs likely developed their emotional intelligence through millennia of domestication, the study suggests horses' ability is rooted in a primal need for survival. As prey animals, they are neurologically wired to be hyper-vigilant to signs of danger in their environment. Detecting fear in another creature—even a human—could signal a nearby threat, triggering their fight-or-flight response.
Dr Léa Lansade from the University of Tours explained the profound implication: "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 mechanism hinges on volatile organic compounds in human sweat. When we feel fear, stress hormones like adrenaline and cortisol alter our sweat's chemical makeup, creating a scent signature imperceptible to us but detectable by animals with highly sensitive olfactory systems.
Broader Implications for Animal Welfare
This discovery adds a crucial layer to our understanding of human-equine interaction. It demonstrates that fear can be transmitted from people to horses silently, without a single word or gesture, potentially affecting their wellbeing and performance. This insight is particularly relevant in contexts like equine therapy, racing, and recreational riding, where a handler's emotional state could directly influence the animal.
The findings also resonate with earlier research into equine physiology. A 2020 study from the University of Sydney established that horses feel cutaneous pain similarly to humans, finding no significant difference in nerve ending concentration in the skin's outer layer. This challenged long-held assumptions within industries like horse racing, where the ethics of whipping have been debated.
Together, these studies paint a picture of the horse as a deeply sensitive creature, exquisitely tuned to both physical and emotional stimuli from humans. The French team concluded that the ability of chemosignals to transcend species boundaries suggests they play a vital role in interspecific interactions, especially between humans and the domestic mammals we live and work alongside.
