Origin of life  on the earth:

Man has always wondered  how he came into existence, who created him, and why he was created. Curiosity in this connection has been so strong that every ancient thinker, philosopher or "prophet",  has tried  to give some answer to this question and suggest some mechanism for the creation of  life. According to an ancient Greek idea, life was transferred from "cosmozoa" (life of outer space) to different planets in small units called "spores". These spores had a  thick impenetrable covering which prevented  loss of water and other necessary components. It was assumed that under favourable conditions of  temperature and moisture, thesc spores gave birth  to the initial living organisms on the, as yet uninhabited,  plancts. This idea presumes a universal and eternal store house of  spores of  life, and thus indeed avoids answering the question as to how life anywhere originated  in the first place. The Greeks, or anyone else at that time, of course, did not know that  the travelling spores would encounter destructive radiations like the ultraviolet and gamma rays in space. In addition to  this, various other theories have been put forward from time to time about the origin of  life. Some of  them were mere speculations, whereas others have some scientific basis.