P M V SRINIVASAN Origin of Life on Earth PART ONE IT WAS only in the last century that man began to comprehend scientifically a process that probably occurred between 3500 million and 4500 million years ago: the origin of life on earth. The problem has attracted the human mind from the earliest times. Every religious and philosophical system and many an influential thinker has devoted serious attention to it. At different stages of the development of society and under different material conditions, the question of the origin of life has been answered in different ways. It has always been the focus of a bitter conflict of ideas between the two camps in philosophy: materialism and idealism. India and China, along with Greece, have had a particularly rich historical tradition of struggle between the two camps.' Starting from the earliest times, materialist philosophers in different parts of the world have asserted that life is material in nature like everything else and that there is no need to smuggle in any spiritual force to explain its origin. They based their conclusions on observation of natural phenomena, everyday experience, and proto-materialist and naive materialist conceptions. But at a stage of the development of knowledge where precise and detailed scientific conclusions about man and matter were not possible, they had no way of establishing their belief with scientific conviction.