Bitter taste evolution

Bitter taste perception evolved as a way to detect chemically diverse compounds that can signal toxins, though many bitter substances are harmless or beneficial.

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TAS2R receptors: A family of G protein-coupled receptors that detect many bitter compounds in vertebrates. Their varied ligand sensitivities provide the molecular basis for bitter detection.
Vertebrate evolution: The evolutionary history of animals with backbones, from early aquatic forms to living groups. Comparisons across vertebrates reveal how bitter-sensing systems changed over deep time.
Phytochemicals: Chemical compounds produced by plants that can affect the organisms consuming them. Many plant compounds taste bitter and may influence feeding decisions.
Sweet taste: A taste quality commonly associated with sugars and other compounds that activate sweet receptors. Sweetness can signal energy-rich foods, unlike bitterness's frequent association with deterrence.
Gustducin: A taste-cell G protein that helps transmit signals from bitter and sweet receptors. Bitter-receptor activation can recruit gustducin to initiate intracellular signaling.
Gene duplication: The production of an extra copy of a gene, creating opportunities for divergence or loss. Duplications helped expand bitter-receptor repertoires in some lineages.
Plant-herbivore interactions: Ecological relationships between plants and animals that consume plant tissues. Bitter detection can shape how herbivores choose among defended plants.
Umami: A savory taste quality commonly elicited by glutamate and related compounds. Umami often signals amino-acid-rich foods, providing a distinct feeding cue.
Taste transduction: The cellular processes that convert chemical stimuli in the mouth into neural signals. Bitter perception is one output of this broader sensory signaling system.
Comparative genomics: The comparison of genome sequences across species to identify evolutionary change and shared ancestry. It reveals receptor gains, losses, and sequence changes among species.