animals and sweetness is a subject that has not received much systematic attention. Little is known about why and how human animals evolved their sweet tooth from nonhuman animals. Nonetheless, existing data reveal some surprising and very interesting discoveries for the relatively few animals that have been studied, and it turns out that the ability to discriminate sweets is phylogenetically old. For example, chemotaxic responsiveness (orientation or movement toward or away from certain chemicals along a concentration gradient) to sugars and sweetness has been discovered in motile bacteria such as E. coli.
