Evolution - A Note II : Organic

In 1857 Charles Darwin published a momentous tome ‘The Origin Of Species’ which gave the Theory of Natural Selection. He also thought that a Struggle for Existence is present in the living world, which we believe should be taken only allegorically. Since the ancient times thinkers have been thinking over the problem of diversity of life on the earth; and also the problem concerning the relationship between the living organisms. Many contributed towards this problem, including Charles’ grandfather Erasmus. Theory of Natural Selection is quite simple if we take it at its face value. Millions of years before a living cell came into existence which started replicating and producing cells of diverse kinds and properties. This eventually led to the creation of diverse forms of life like Bacteria, Fungi, Plants and Animals which kept diversifying into different kinds.

At present we know that the Earth came into existence about 4.5 billion years ago; and living systems started emerging about 2.5 billion years ago – a gap of 2 billion years. During this process the Earth’s surface changed, often dramatically. Comets and other stellar bodies kept bombarding the surface. Inner convulsions further brought about transformations. However during such cataclysmic happenings the living systems survived, diversified and kept evolving.

In 1953 the double helical structure of DNA was discovered. The DNA is present in all the living cells; in prokaryotes (lowly organisms) the DNA is present at a site inside the cell, while in eukaryotes (higher organisms) DNA is stored in chromosomes. Along with DNA living cells also contain RNA, of different varieties. It has been known that chromosomes are involved in the formation of newer cells inside a eukaryote; and there is some difference in the chromosomal sets of human males and females. Further it seems that all the animals have chromosomes which are related to one another both structurally and functionally. The involvement of RNA in the life process is also as important as DNA. The protein synthesizing machinery inside the cell, the Ribosome, made up of RNA and protein. Further the genetic information which flows from genome (the collection of chromosomes) is passed through a particular kind of RNA. The Amino Acids which are used to make protein is also carried by RNA to the Ribosome. Only last year it was discovered that a soup which contained all the necessary atoms and molecules which make RNA, under specific conditions, did produce a small RNA molecule. It is interesting to know this small ‘primitive’ RNA molecule is present in the RNA of all living cells. Which suggests that this RNA initiated the process of cell formation. Further it is estimated that this RNA molecule was produced on Earth some 3 billion years ago, just after the bombardment of the Earth’s surface by the comets etc. for about 200 million years.

All the evidences which have accumulated since the publication of Darwin’s book and which includes fossils of many types and the relationship of various tissues and organs of living systems clearly suggests that the theory of Natural Selection i.e. the Evolution has been active on this planet to produce diverse forms of life which we observe at present.