Evolution is the change in heredity adapted by a massive population across the world. It brings the change at each and every level viz. Macroscopic or microscopic. When we talk about the history of the evolutionary process, there are two basic and vital processes. First is speciation which means evolving and formation of new species. The second is extinction which means the end of certain species. Another fact which still remains intact is that species will share similar traits if their head ancestor is common.
History of Evolution: In the mid-19th century, a scientist named Charles Darwin came up with the theory of evolution which was published in his book called “On the Origin of Species.” It stated that offspring which are produced, their chances of surviving life are high.
There have been three observations regarding life:-
1. Traits or behavior vary from person to person. For example, it is quite evident that no two people are same.
2. Different species have a different rate of surviving any hostile condition. Also, their reproduction rate and time also differ.
3. Traits are transferable from generation to generation. For example, the fitness traits of a healthy family are passed on to a younger generation. Although it is observed that the parents are more adaptive and they have better reproduction scale as they are more used to specific biosphere conditions.
The process through which the changes occur from one generation to another is known as Evolutionary Process.
MAIN THEORIES OF EVOLUTION
1. Lamarckism or Theory of Inheritance of Acquired Characters :
It was proposed by Jean Baptiste de Lamarck. This theory tells the comparison between species in relation to fossil records. Lamarck stated that how organs of the organism or the changes in the body are recorded with the changes in the environment. Thus he defined adaptive nature as a function of the evolutionary process. One of the major postulates of this theory was that there are certain organs which are of more use, whereas some are of lesser use. The ones with lesser usage ultimate get vanished and the ones with high usage lead to maximum efficiency. The species evolved in certain climatic conditions and this changes are called as adaptive or acquired characters.
2. Darwinism or Theory of Selection: Charles Darwin is the most dominant figure in the study of evolutionary process. He studied the major population of animal’s species and concluded that there is the struggle for existence. It was later on supported with Survival of the fittest term.
3. Mutation Theory of De Vries: This theory was proposed by Dutch Botanist, Hugo de Vries. He carried experiments on plants and observed their pollination (self). He carried out the experiments on a large number of plants. The maximum was just like its parents. But the minor portion was different. The loss of the character is called a mutation. This mutation forces the development in the different direction leading to new species.
4. Neo-Darwinism or Modern Concept or Synthetic Theory of Darwinism:
The detailed studies of Lamarckism, Darwinism, and Mutation theory of evolution showed that no single theory is fully satisfactory. Neo-Darwinism is a modified version of a theory of Natural Selection and is a sort of reconciliation between Darwin’s and de Vries theories.
After studying three theories, it became evident how these theories were not enough. Thus there was a revised theory by combining all other theories. It said that the mutation and heredity are combinable called as chromosomes which are located in a linear manner.
Read: Human Evolution