 Dear students, in this topic we shall discuss the kin selection and inclusive fitness. Kin selection is an altruistic evolutionary strategy which favours the reproductive success of an animal's close relatives, even at a cost of animal's own survival and reproduction. Kin selection is an instance of inclusive fitness. It combines the number of offspring produced by an individual himself and the number of offspring it can ensure by sporting other close relatives or siblings. This is an behaviour in which an individual does not try to sacrifice himself for close relatives because he knows that he will die, but if he is alive, he will keep on increasing the population. This is kin selection. Dear students, kin selection has genetic basis. Because fitness of an individual is based on the genes it passes on to the next generation. The fitness also means that if the common genes present in an individual are passed on by his close relatives. Genes' perpetuation will be in both cases, so kin selection is a genetically derived trait. Through kin selection, a gene carried by a particular individual passes on to the next generation through a related individual. Kin selection explains how nature selection acting on relatives of an animal can affect the fitness of an individual. For kin selection to be effective, individuals of a group must be able to recognise or identify their relatives. So kin selection is only in those animals or in those animal groups in which the social structure is quite advanced and the members recognise each other's relatives. Such groups are found in primates and in social insects. Dear students, the altruistic kin selection behaviour is most evident in the sacrifice of parents for their offspring. Usually parents sacrifice for their offspring. This is kin selection. Parents sacrifice of their own reproductive potential actually increases their fitness. Because the reproduction by their kin will maximise the spread of their genes in the population. Even the children have their own genes, so if the children are born, they perpetuate the genes. This means that the potential of the genes will maximise and this is the success of the parents. Dear students, now we shall discuss inclusive fitness. Which is a matter of fitness of a group of members of a species. This is not of an individual, but of a group of individuals. This is not a close relative concept, but a group concept. An organism's inclusive fitness is determined by its personal fitness plus its weighted effects on the fitness of every other individual in the population. This weighted effect is determined by relationship coefficient i.e. the related genes. Inclusive fitness is actually a trait which favour natural selection. Because natural selection acts to maximise the genetic and reproductive fitness of a group i.e. population. Natural selection does not think about individuals. The genes of an individual are maximised in the gene pool. In fact, it selects favourable genes in a population and favour them. This is why natural selection favour inclusive fitness more than kin selection. Inclusive fitness behaviour of an animal is when we see that individuals of a species help those individuals who are not close relatives. So this behaviour is inclusive behaviour.