The free time that is permitted humans because they have the ability to use fat stores as energy, on the other hand, has enabled us to build civilizations, DiLorenzo added. Perhaps because taste is so key to our experience of pleasure and well-being, losing it is a terrible drag, both emotionally and physically. Taste disorders, in fact, are linked to a variety of health problems, particularly in infants and the elderly. There is a lot of work being done to enhance tastes as a way of enhancing appetite in infants. Likewise, diminished appetite in the elderly is linked to a reduced ability to taste foods.
Researchers also know that there is a strong link between depression and taste.
Though it isn't certain which comes first, the loss of taste or depression, people who are unable to distinguish tastes are far more likely to be depressed than the average person, and many people with depression experience loss of or impairment in their sense of taste, DiLorenzo said. Though humans don't have a synapse for taste in the parabrachial nucleus of the pons, DiLorenzo thinks the nucleus of the solitary tract in humans does what both structures do in rodents. But like the structures that are responsible for hedonic decisions in rodents, the structure that determines whether humans like or dislike tastes is buried in the brain stem near such basic, primitive functions as heart beat and respiration. They don't actually do the swallowing, but they determine whether the stimulus is wonderful or yucky. In fact, if you cut off the rest of the brain from those sites, you can still make those decisions.