 Dear students, in this topic we shall discuss altruism or altruistic behavior. Altruism is a selfless behavior in which an individual endangers his own survival or sacrifices some of its own reproductive potential to benefit another individual. It is an innate trait with genetic basis and is developed through the process of evolution in many animal species. Altruism is particularly prevalent in animal species which have complex social structures for example in primates and some other mammals and insects. However, there are wide individual variations in tendencies toward altruism. Dear students, altruism is a different kind of social behavior. It has been hard to explain within the framework of darmanism and natural selection which emphasize on fitness by selfish means. This is a phenomenon which is opposite to this because it reduces the fitness of the altruistic individual. Dear students, the phenomena of altruism has certain significance. In some ethology, posts or benefits of behavioral traits come here in terms of reproductive fitness or expected number of offsprings. When an individual altruistically behaves, it reduces the number of offsprings it is likely to produce itself. But by sacrificing its own favours to save others, an altruist actually indirectly boosts the number of offsprings it is likely to produce. It means that altruism is not a phenomenon which is a waste but it has certain benefits. Dear students, now we shall discuss the examples of altruism. This squirrel on seeing a predator gives an alarm call. This alarm call is to alert other members that the predator has come, you all should escape. But in this case, the squirrel falls asleep and usually falls asleep. Similar alarm calls are also given by crows and monkeys. In social insect colonies, for example ants, wasps, bees, the sterile workers which have no reproductive potential, they devote their whole lives to care for the queen, to construct and protect the hive, foraging for food and tending the larvae. This is a maximally altruistic behaviour in which the individual has no benefit at all and he is not doing anything for himself, he is doing everything for others. Similarly, worker bees show another behaviour, they sting the intruders. This means that it is also an altruistic behaviour, altruistic behaviour is also seen in vampire is also an altruistic behaviour.