The evolutionary perspective explains the biological behaviour by demonstrating the behavioural and physiological changes that occur as a result of evolution being necessary for the survival of species. For instance, increase in the capacity for cognitive behaviour like perception, memory and use of language for communication among humans is a result of the evolution. Such type of changes have occurred due to the impact of the surrounding environment and is related to abilities like finding food, avoiding predators and protecting the offspring. This is manifested in humans in the following ways: The human brain has evolved from smaller to bigger in size. Human beings can walk upright on their two legs. Human beings have got a free hand with a workable opposing thumb. Neurons transmit information with the help of its dendrites, axon, soma and terminal buttons by converting stimuli into electrical impulses.