Evolution and Theory Of Evolution | Information & Facts

Evolution

Evolution is the gradual change occurring in living organisms over a long duration. This is a very slow-going process through which development of organisms is achieved. All the stages in changes occurred in various components ranging from stars and planets in space to the biosphere present on the Earth should be included in the study of evolution. Formation of news pecies due to changes in specific characters of several generations of living organisms as a response to natural selection, is called as evolution.

3.5 billion years ago, life had been non existent on the Earth. At the beginning, there  may have been only simple elements in the  ocean on the Earth and simple type of organic and inorganic compounds may have been  formed from those. Complex compounds like proteins and nucleic acids may have formed over the long period from those simple compounds. First primitive type of cells may  have been formed from the mixture of different types of organic and inorganic compounds.Number of those cells may have increased at the cost of surrounding chemicals. There may had been some differences among those cells and according to the principle of natural selection, some may have shown good growth and some may have perished which could not adjust with the surrounding.

At present, crores of species of plants and animals with huge diversity regarding shape  and complexity are present on the Earth.  Animal diversity ranges from the unicellular  Amoeba and Paramoecium to man and giant  whale. The plant diversity consists of various  species ranging from unicellular Chlorella to  the huge banyan tree. The life exists on Earth  everywhere from equator to both the poles.  Organisms are present at all the places like  air, water, land, rock, etc. Humans have  shown curiosity about origin of life and  reasons for such a great diversity in life present on the Earth since ancient period. Different theories about origin and evolution. of life have been proposed till today of which theory of 'Gradual development of living organisms is accepted.

Theory of Evolution:

According to this theory, first living material (protoplasm) has been formed in ocean.In due course of time, unicellular organism was formed. Gradually, changes occurred in the unicellular organisms from which larger and more complex organisms were formed. All those changes were slow and gradual. Duration  of all these changes is at must 300 crore years. Changes and development in living organisms had been all round and multi-dimensional and this led to evolution of different types of organisms. Hence, this overall process is called as evolution which is organizational. Progressive development of plants and animals  from the ancestors having different structural and functional organization is called evolution.