Altruism (biology) most common mechanism of reciprocity in nature, this kind is present in humans, primates, and many other mammals. Also known as, "If you're nice, I'll be nice too." This mechanism of reciprocity is similar to the heuristic of the golden rule, "Treat others how you would like to be treated." Parties mirror one another's attitudes, exchanging favors on the spot. Instant attitudinal reciprocity occurs among monkeys, and people often rely on it with strangers and acquaintances. Also known as, "what have you done for me lately?" Individuals keep track of the benefits they exchange with particular partners, which helps them
Greek letters used in mathematics, science, and engineering as variables in mathematical formulas, a Greek letter appearing similar to the TeX rendering is more likely to be encountered in works involving mathematics. note: a symbol for the empty set, formula_23, resembles Φ but is not Φ Greek letters used in mathematics, science, and engineering Greek letters are used in mathematics, science, engineering, and other areas where mathematical notation is used as symbols for constants, special functions, and also conventionally for variables representing certain quantities. In these contexts, the capital letters and the small letters represent distinct and unrelated entities. Those Greek letters which have the same form as