The more complex functions of the human brain—social interaction, decision-making and empathy, for example—seem to have evolved from these basic systems controlling food intake. The sensations that control what we decide to eat became the intuitive decisions we call gut instincts. The most highly developed parts of the human frontal cortex that deal with decisions and social interactions are right next to the parts that control taste and smell and movements of the mouth, tongue and gut. There is a reason we kiss potential mates—it’s the most primitive way we know to check something out.
Incidentally, death is life’s invention too.