Charles Darwin’s Theory of Evolution and his Concept of Species

In the beginning of nineteenth century, when the modern biology was initiated, the first clear recognition and demonstration of the fact of evolution was made by the French naturalist Lamarck who proposed his theory of organic evolution in Philosophie Zoologique discussing brilliantly that all life is the product of evolutionary change. His theory is known as inheritance of acquired characters or theory of use and disuse. However, his theory could not stand up scientific tests so it was not accepted and is of historical importance. Charles Darwin proposed his theory to explain the mechanism of evolution. His theory is based on observations and deductions which was published in his book in 1859 ‘Origin of species by means of natural selection’. His theory had great impact on scientific and intellectual worlds and was acceptable by most biologists. His theory has two components: (i) descent with modification-all species have descended from pre existing species and (ii) natural selection acts as a causative agent of evolutionary change. It is considered as the most important contribution in the history of science which was suggested by Darwin that all the organic beings which have ever lived on this planet have descended from some one primordial form. The theory of evolution proposed by Charles Darwin and the concepts of species followed by him which has been severely commented and debated are briefly described.