Inter- and Intra-Species Communication of Emotion: Chemosignals as the Neglected Medium

SIMPLE SUMMARY: Human body odors contain chemosignals that make species-specific communication possible. Interspecies communication studies were conducted on dogs and horses subjected to human chemosignals produced in happiness and fear emotional states. Dogs showed behaviors consistent with human emotions, while horses exhibited differential activation of the autonomic nervous system. These results are leading the way for further studies on human–animal communication through emotional chemosignals. ABSTRACT: Human body odors contain chemosignals that make species-specific communication possible. Such communication is without communicative intent and is generally below the threshold of consciousness. Human recipients of these chemosignals produced during emotional conditions display a simulacrum of the emotional state under which the chemosignal was produced. The investigation of an inter-species transfer of emotions via chemosignals was initiated by considerations of the historically anchored interdependence between humans and domesticated species, such as dogs and horses. Indeed, experiments with dogs have demonstrated that human body odors produced under emotional conditions of happiness and fear led dogs to manifest corresponding emotions to those experienced by humans. Preliminary data from horses also show that human body odors collected under fear and happiness conditions activate the autonomic nervous system of horses differentially. These studies indicate the possibility of a road to open our understanding of inter-species emotional communication via chemosignals.