是藥三分毒
Most drugs work by interfering with physiological processes within cells, so medicines have the potential to be toxic when ingested in sufficient quantity. Bitter taste is thought to have evolved as a deterrent against ingesting toxic substances,4 which may explain why many drugs taste bitter.
Glendinning JI. Is the bitter rejection response always adaptive? Physiol Behav. 1994;56(6):1217–1227. doi: 10.1016/0031-9384(94)90369-7.
哺乳動物能感知鹹、酸、甜、苦、鮮等口味(註:貓無法感知甜味),這五種味覺感知模式中,苦味感知具有特別重要的作用。因為很多天然有毒物質都具有苦味,這種厭惡的反應有助於演化成為一種防禦機制來避免有害物質的攝入。如果從進化的觀點來看,或許遠古生物無法辨別苦味,但在基因變異的過程中,若有一個生物體由於基因變異而產生能夠識別苦味的 味覺感受器,一旦族群攝食有毒植物時,只有這個生物不吃毒物於是生命就能存留了下來,牠就能把識別苦味的感受器遺傳給了牠的後代。