Sweetness Preferences and Evolution

The evolutionary explanation is that our survival depends on our ability to take in energy from our diet, and one of the major sources of such energy is carbohydrates, which include sugars. See sweets in human evolution. Sweetness, therefore, is an excellent signal for the presence of energy. In order to maximize energy intake, preferences generally rise with sweetness intensity. Human newborns not only respond positively to sugars, they also discriminate among different sugars, consuming more if given free access to those that are more sweet (sucrose and fructose), as compared to less sweet glucose and lactose. Moreover, the fact that sweetness preferences can be observed in very many species across diverse animal classes argues strongly for the importance of sweetness as a nutritive signal. In mammals, the only species that do not respond positively to sweetness are obligate carnivores such as cats. See animals and sweetness. Any mammal species that consumes plants is thought to show sweet preferences—signaling the adaptive importance of plant-derived carbohydrates.