Eating is one of the fundamental requirements, along with breathing, necessary to sustain life. If a person does not breathe for some minutes death occurs very quickly; for someone not eating, although it may take several weeks, the fact of death is no less inevitable. Perhaps this is why, throughout the animal kingdom, feeding is such a major part of the daily routine and has become in some species a part of ritual. In primates in particular, feeding routines have assumed particular importance, and are regularly used to placate aggressors. In humans mutual feeding has also evolved as a major mechanism for showing affection or sexual interest (Morris 1967).