Aggression and cooperation have been the source of many ethology and sociobiology related discussions which have in turn lead to the development of several important models, such as the hawk-dove, cooperator's dilemma and snow-drift games. As these models rarely act in conjunction however, they are considered "separate" means of explaining each phenomenon. Moreover, many of the parameters used in the models are quite abstract and difficult to adapt to actual organisms. By introducing four

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... able parameters, the cost of aggression, relatedness, mutual helping and one-sided helping effects into the basic hawk-dove game and limiting the situation to a non-repeated (non-learning) game, we could showed a mixed ESS of aggression and cooperation, which must appear continuous variation of aggressiveness with relatedness in nature. Furthermore, the ESS conditions under which aggression, snow-drift, cooperation and 'altruism' occur, can be expressed in a single pay-off matrix.