From the moment that an animal is born it has to make decisions．It has to decide which of the things around it are for eating，and which are to be avoided；when to attack and when to run away．The animal is，in fact，playing a very dangerous game with its environment，a game in which it must make decisions——a matter of life or death．
    Animal’s ability to act reasonably is believed to come partly from what we may call ” genetic(遗传性的)learning”，which is different from七he individual(个体的)learning that an  animal does in the course of its own lifetime. Genetic 1earning is learning by a species—animals of the same kind——as a whole．and it is achieved by selection of those members of each generation that happen to act in the right way．However，the role of genetic learning depends  upon how similar the future environment is to the past The more important individual experience is likely to be．the less important is genetic learning as a means of getting over the problems of the survival game．Because most animals live in ever changing environments from one generation to the next，it is not surprising to find that very few species indeed depend wholly upon genetic learning．
    In the great majority of animals，their particular ways of acting in a new environment are a compound (复合体)of individual experience added to the action patterns animals are born with.    That is why animals can survive．