A new study conducted by the French Institute for Horse and Riding (IFCE) and published in the scientific journal PLOS One has scientifically confirmed that horses can detect human fear through smell. The research shows that horses approach fearful humans more cautiously and are more easily startled.
Previously, scientists knew that horses could understand human emotions through facial expressions and tone of voice; however, the idea that they could detect "fear scent" remained theoretical due to the difficulty of studying the olfactory sense.
METHOD AND FINDINGS
Researchers collected sweat samples from volunteers' underarms while they watched videos that induced fear or joy. These samples were then presented to 43 different mares, and their reactions were observed.
Horses exposed to fear scent reacted more intensely to sudden events, like an umbrella opening unexpectedly, and startled more easily.
They were also less willing to approach humans or investigate unfamiliar objects when sensing fear.
The fear scent caused noticeable changes in the horses' heart rate and stress hormone (cortisol) levels.
SIGNIFICANCE FOR RIDERS AND TRAINERS
Co-author Lea Lansade described this as an interspecies "emotional contagion," emphasizing the importance of riders and handlers being aware of their own emotional states.
"Even though humans cannot control the emotional scents they emit, riders should focus on staying calm. When you are relaxed, your horse senses this and reacts less."
The researchers plan to investigate next whether horses respond similarly to other human emotions like sadness or disgust, and whether humans can detect horses' emotions through scent.
