From Soup To Man

The emergence of man from the first forms of life in the primordial soup of the oceans, some 3500 million years ago, cannot be traced completely. Few fossils exist from more than 570 million years ago, and in any case early forms of life were soft-bodied and left little or no trace. The first forms of life were undoubtedly single-celled creatures, perhaps not unlike the primitive amoeba of today. From these single-celled creatures, known as protozoans, evolved the multi-celled animals known as metozoans. And from the metozoans developed the chain of species that culminated in man.