Certainly horses can cause happiness, but can they smell when their humans are happy?

Drs. Gün Semin, Anna Scandurra, Biagio D’Aniello, Paolo Baragli and Antonio Lanatà reviewed multiple studies and concluded that the horses used in the research showed different activation of their autonomic nervous systems depending on if the human they were exposed to was happy or fearful. These findings suggests that emotional chemosignals carry meaning across species and can enable inter-species communications.

Horses may be particularly attuned to human interaction because of their long domestication process, which has caused them to acquire skill that allow them to “communicate” with humans by recognizing gestures, words and even facial expressions. Research has shown that horses are able to synchronize their heart rate and other physiological measures when in contact with humans. The research team wanted to explore if horses had additional means of understanding human emotions and they reviewed several studies.

One study conducted by Antonio Lanata showed that human body odors triggered systematic sympathetic and parasympathetic changes in horses. One possible explanation is that odors produced in emotional contexts contain distinctive chemical compounds that activate the same responses in different species. Another is that the responses are developed as part of the socialization/domestication process and that the horse has become sensitive to the emotion-induced odor.

Collectively, the studies reviewed suggest that there are distinctive chemical fingerprints, independent of the senders’ and the receivers’ cultural community. These findings suggest that there is chemical invariance in the sweat compounds. What remains open is if such invariant compounds activate an automatic emotional response or whether the emotional responses are learned.

What do you think? I’m pretty sure that we send off all kinds of chemosignals to our more sensitive animal friends.