Darwin's Contribution: The Theory of Evolution

Charles Darwin, an English naturalist of the 19th century made an extensive study of nature for over 20 years. He collected the observations on animal distribution and the relationship between the living and extinct animals and finally found that the present living animals share similarities to some extent not only between them but also with the other species that existed millions of years ago and among which some have become extinct.

Carles Darwin is known as the father of evolution due to his contribution to the establishment of the theory of evolution. His theory helped in removing all the conventional old beliefs which said that the formation of various species was a supernatural phenomenon or act of the Almighty. Darwin’s evolutionary theory of natural selection gave a more rational explanation of the formation of new species. As per natural selection, various species originated from a single species as a result of adaptation to the changing environment.

Also Read: Foster’s Rule

The Theory of Evolution

Darwin had the following ideas regarding the theory of natural selection:

• Species keep on evolving or changing with time. As the environment changes, the requirements of an organism also change and they adapt to the new environment. This phenomenon of changing over a period of time as per the natural requirements is called adaptation.
• As per Darwin’s theory, only the superior changes are naturally selected and the inferior ones are eliminated. Thus, not all adaptations contribute to progressive evolution. For example, people living in tropical countries have more melanin in their bodies to protect them from the sunlight.
• Almost all organisms share common ancestry with some organisms. According to Darwin, all organisms had one common ancestor at some point in time and kept on diverging ever since. His evolutionary theories support the convergent theory and divergent theory of evolution with examples.
• He also studied that the birds of Galapagos Island (Darwin’s finches) developed different beaks as per the availability of the food. This proved adaptive radiation. Similarly, he also observed the Australian Marsupials which showed a number of marsupials emerging from an ancestor.
• According to Charles Darwin, evolution is a very slow and gradual process. He concluded that evolution took place over a very long period of time. As we talk about the time period in evolution we usually refer to billions of years. The generation of a species from another takes a long period of time. It is a very steady process as the changes and adaptation take a long time to stabilize and give rise to a new species.

Natural selection takes place in four different ways as follows:

1. Variation – The changes accumulated over a period of time in an organism usually give rise to a new species.
2. Inheritance – It is the passing on of the variations over generations which ultimately leads to speciation.
3. A high rate of growth of population – This gives rise to more organisms being reproduced by a species than the environment can support.
4. Differential survival and reproduction – The superior variations lead to the survival of a particular organism and the inferior or negative variations lead to extinction. The superior variations are the ones inherited during reproduction.

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