Detection of Environmental Cues by TAAR Family.

The trace amine-associated receptor (TAAR) family is a chemosensory system dedicated to the detection of volatile and water-soluble amine odorants. Unlike canonical odorant receptors (ORs), TAARs function as highly tuned evolutionary sensors that assign innate behavioral valence to critical ecological cues. In this chapter, we examine how TAARs decode the environmental amine landscape to drive survival and social behaviors, focusing on predator avoidance triggered by 2-phenylethylamine, as well as conspecific attraction and social hierarchy formation mediated by trimethylamine. We trace the biophysical adaptations of these receptors from aquatic to terrestrial environments and map the dedicated neural circuits connecting peripheral amine detection to limbic centers. Beyond the olfactory epithelium, we highlight the role of ectopic TAARs as internal biosensors for microbiome- and diet-derived amines across the central nervous, immune, and cardiovascular systems. Finally, we discuss how the contracted human TAAR repertoire continues to influence modern dietary preferences, positioning the TAAR family as a critical interface between environmental sensing and physiological homeostasis.