Think back to your first encounter with a horse. Were you warned that if you were afraid, the horse could smell your fear? It turns out that was good advice.
People emit a particular chemosignal while experiencing a specific emotion that induces the same emotion in another person who smells that odor. Chemosignals are chemical signals the human body gives off, primarily through sweat. Now researchers have found that horses also can smell human emotions.
Dr. Antonio Lanatá and his colleagues at the University of Pisa, Italy, have found that horses can smell fear and happiness. While these are just two emotions the researchers identified, further studies may reveal horses can pick up additional emotions from the body odors humans emit.
The researchers theorized, “We know that horses perform unexpected reactions when being ridden by a nervous person. This research background led us to suspect that the olfactory system of horses is likely to enable them to read human emotional states by means of the axial chemosignals humans emit.”
Human participants in the horse study watched scary movies or happy movies while wearing armpit pads to collect their sweat. The research team asked the subjects to observe a strict protocol for two days prior to the sweat collection that eliminated exposure to odorous foods, alcohol, tobacco, or external odors that could compromise the results. They also were asked not to exercise excessively.
Seven study horses of different breeds were fitted with wearable telemetry devices that measured their heart rate variability. When they were allowed to sniff the armpit pads that contained fear sweat or happy sweat, their autonomic nervous systems reacted. The autonomic system controls heart rate and breathing.
The study used sophisticated telemetry instrumentation that showed a marked difference between the horses' physiological responses to human fear and to human happiness.
“Our results revealed that human body odors induce sympathetic and parasympathetic changes and stimulate horses emotionally, suggesting interspecies transfer of emotions via body odors,” Lanatá concluded.
Learned or Instinct?
Lanatá explained via e-mail that when a horse sniffs a person introduced to it, the horse is sizing up the individual to detect his or her emotion, among other things. This information tells the horse how to react to that person.
This study found that horses react to the smell of human fear and happiness, but are those learned responses or instinct? For example, if the individual most often handling a specific horse acts aggressively when fearful, perhaps striking the horse, does the horse expect to be struck when it smells fear from any human? Conversely, if the horse's experience with fearful humans has been that they retreat or otherwise allow the horse to have its own way, will the horse take advantage by bullying every human who smells of fear?
Happiness is less complicated. We all know that particular individual whose cheerful presence makes everyone feel good. Science has shown that horses also recognize facial expressions of happiness, and a happiness odor could reinforce that perception.
Armed with the knowledge that horses can smell human emotions, would it be possible to trick the horse by wearing a scent that masks the natural human odor?
“What an interesting question,” Lanatá said. “To be honest, I do not know, but it would be possible if we were able to produce an odor of positive emotion. Indeed, we are working on that to produce real emotional odors. But it is another work.”
In his novel The Horse Tamer, renowned children's author Walter Farley offered what he called the Arabian Secret:
“To make a wild horse approachable or a vicious horse gentle, take two parts of the oil of rhodium and one each of cumin and anise. Put in a bottle and cork tightly until ready for use. A little of this is to be rubbed on the hands, and while held before the horse, approach from the windward side. When near enough, rub a little on the nose and in 10 or 20 minutes the horse will be ready to receive your kindness and plan of teaching.”
Lanatá said his team's study was conducted in a laboratory, where these questions were not answered. He is confident that their results open the door for further exploration of this interesting phenomenon in other fields of horse-human interaction.
“If our results are confirmed by ourselves or other researchers,” Lanatá wrote in his email, “it will make many positive outcomes, first of all in the horse education and training of the animal, because the trainer/educator should keep in mind that his emotions are transparent to the animal, then some unexpected animal reactions could be well understood, and so on. Moreover, in the animal-assisted interventions, these results could improve our ability in managing horses for therapies, especially with people with disability, mental disorders, or for autism-affected people.”
Editor's note: A previous version of this story incorrectly defined oil of rhodium (rosewood oil). That description has been updated.
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