The effect of natural selection on colonies or population favouring one group in preference to other may be referred to as group selection. A group can be the smallest collection of individuals within a population or a colony. Group selection, it must be understood, is distinct from selection among individuals. The fitness of the genotypes between groups may vary within a population. The concept of altruism can be extended to groups as well. A colony consisting of many altruists has better chances of survival than a colony consisting of selfish individuals. Let us take hypothetical situatioii where individuals of a colony, reproduce indiscriminately having no regard for the carrying capacity of the environment. On the other hand, consider a colony of individuals with genes restricting population growth, utilising optimally the food sources of the environment. The selection would essentially favour the latter group and the former may eventually face extinction.