ABSTRACT
“We are what we eat” may have been, originally, social comment. It also reflects biological reality. Without adequate intake of essential nutrients, no living organism grows, matures, or reproduces. Complex multicellular organisms have developed processes by which sources of nutrients are ingested (enter the body) and digested in the gastrointestinal tract (mechanically and chemically reduced to absorbable nutrients). In mammals, that process has come to involve a set of highly integrated behaviors relying on sensory information from the visual and auditory systems. Not only does sensory information lead to a locomotor response, it also activates the autonomic nervous system preparing the mouth and stomach for food intake. The special senses play a vitally important role in the acquisition of food: in identifying food sources, in facilitating food acquisition, and in evaluating its edibility. More than a century ago, Pavlov showed that the conditioned anticipation of food would trigger reflex mechanisms which, by producing saliva, facilitate the conversion of a food source into “digestible material.” As human society has developed, the “sight,” “sound” and “smell/taste” of food has assumed social significance. The psychosociology and psychophysics of sight, sound, and touch, as well as the intraoral perception of taste and texture have, and are, playing a major role in the production of secondary (processed) food sources for consumption by most “developed” populations. While sensory “choices” may be a greater determinant of behavior (selectivity of acquisition) in a “supermarket society,” it appears that the processes and mechanisms by which food is rendered digestible have changed little as mammals have evolved, despite the morphological specializations of jaws and teeth associated with differences in their primary food sources.
