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INTRODUCTION
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brain, there are what are called motor regions of the body, some controlling the movements of the hind legs, some controlling the movements of the front legs and so on. When we follow the development of this brain in the mammals, we find the appearance of some brain regions which are not characterised either by sensory functions or motor functions. These areas of the brains were called silent areas, because the physiologists were not able to determine their function accurately by experiment. Later on it was discovered that these silent areas perform a very important function of co-ordinating the different elements of sensory awareness with appropriate mascular reactions controlling the general behaviour of the animal and these serve as the fundamental basis of the origin and development of consciousness. This hypothesis is fully corroborated when we watch the development of these silent areas in the brain surface of the mammals
When we come to the simian type of quadrupeds, we find a critical and interesting turn in the brain development. Probably frightened by the pre-historic giants, certain quadrupeds had to take up to arboreal life by climbing up the trees and living there the major part of the time in order to preserve themselves, from the danger of the enemies below. This necessarily resulted in the liberation of the front legs which were converted into hands capable of grasping at things with the flexible fingers and So on This liberation of the front leg led to immense possibilities of future developments found in man. Beginnings of the human culture and civilisation may be traced to this critical turn in the evolution of life where the front legs changed into hands and which again led to an erect posture of the animal standing on the hind legs alone, thus assuring in the advent of man in the world. We now perceive the subordination of the sensory areas of the brain and the major portion of the surface of the brain assigned to motor functions to the functions of the association of different centres. Thereafter we find that the so-called silent centres otherwise called association centres of the brain becoming the dominant area of the brain, and they are at the maximum in the human brain, thus indicating that they form the functional basis of consciousness which is the fundamental characteristic
