The Process of Evolution
The process of evolution was detected in ancient times. Both in India and in Greece, there were important ideas of evolution. In modern times, the theory of evolution is mainly the work of Linnaeus (1707-78), Buffon (1707-88), Erasmus Darwin (1731-1802), Lamarck (1744-1829), Charles Darwin (1809-82) and his followers.
On the Origin of Species written by Charles Darwin (1859) gave details and demonstrations of his scientific theory of evolution, according to which, life on the earth evolved by a gradual and yet continuous process from the earliest forms of living organs to the latest product, man.
Natural selection, variation and heredity are said to be the factors through the operation of which new species arise out of existing ones. When new characters are produced by the variability of organisms, natural selection decides their survival or death. If the characters do not adapt to their environment, they are eliminated in the competition. If, on the other hand, they equip themselves better for the struggle, they tend to survive. The offsprings of the successful tend to resemble the parents in exhibiting the favoured variation to a greater degree than the parents, and a new type becomes established by a continuous piling up of small useful accretions through many generations.
The two original components of Darwin's theory were (I) that evolution is gradual, and (ii)that the nature of the change is dictated by natural, not divine, selection. Both of these are closely interlinked, and both are at the heart of controversy today, as they were in Darwin's time.