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Needing and Nourishing
normal actions of the brain very crudely. Thus, the operations of the whole system determine not only how actions are normally related to bodily needs but also, in man, how the rewards are influenced by the activities of certain brain-areas and the chemical substances contained by them. These areas are responsible for the quality of affection, pleasure, satisfaction or the reverse.
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These reward - centers are influenced by signals coming both from outside the body and within it, including, for example, those from the nose and from the taste-buds of the tongue. A specially interesting pathway begins in the cells of the locus coeruleus, lying near the taste-centers of the medulla oblongata showing some relationship between the sensation of taste and the drive to search for food. 4. Selection by Instinct
In ancient times, both men and animal had the instinct to guide them to find whatever they needed to keep them healthy and to detect and reject the poisonous and unhealthy. They made special efforts to meet particular deficiencies. Children, for example, deficient in calcium, will cat plaster. Some of these capacities for selection of taking what is needed and rejecting what is harmful are certainly innate while others are learned. Unfortunately, while the animals have retained the capacity, humans, with progress of civilization, gradually lost the instinct to a great
extent.
