“I used to drink milk all the time when I was young, but now I hardly ever do. Why did I change?”
“Why can my wife never seem to get enough sweet or salty snacks, even though she knows they're bad for her?”
“Five years ago I ate a hot dog and a few hours later got really sick to my stomach. I still can't stand even the thought of hot dogs. Will this ever go away?”
“Our son won't eat vegetables, but the rest of the family eats them. How did this happen? What can we do?”
Do any of these questions sound familiar? It seems that almost everyone has a food preference or food aversion of mysterious origin, or one that he or she would like to change. Parents worry about what their children like to eat and what they refuse to eat, and for good reason. (See Figure 5.1.) Not only is a balanced diet synonymous with good nutrition, but what you eat is known to influence the incidence and course of many diseases. For example, cutting down on saturated fats and increasing the proportion of fiber in our diets may decrease the risk of heart disease and some types of cancer. 1 Food preferences and aversions clearly have medical as well as social consequences.
The previous chapter explained how people and other animals tell one food and drink from another. Given that animals can tell foods and drinks apart, and assuming the foods and drinks are all equally and easily available, which ones do animals prefer and which ones do they dislike and why? This chapter and the next one will tell you what scientists have discovered about the nature and causes of food aversions and food preferences.