Ans. Variations lead to Evolution
Organic Evolution
Organic evolution (biological evolution) is the change in the characteristics of a population or species of organisms over the course of generations. The evolutionary changes are always inheritable. The changes in an individual are not considered .as evolution, because evolution refers to populations and not to individuals. Organic evolution includes two major processes:
• Alteration in genetic characteristics (traits) of a type of organism over time; and
• Creation of new types of organisms from a single type.
Theory of Special Creation
The study of evolution determines the ancestry and relationships among different kinds of organisms. The anti-evolution ideas support that all living things had been created in their current form only a few thousand years ago. It is known as the "Theory of Special Creation". But the scientific work in eighteenth century led to the idea that living things might change as well.
Theory of Natural Selection
Charles Darwin (1809-1882) proposed the mechanism of organic evolution in 1838. It was called as "The Theory of Natural Selection". Darwin proposed this theory after his S-year voyage on the HMS (His Majesty's Ship) Beagle. He also published a book "On the Origin of Species by Means of Natural Selection" in 1859.
Darwin's theory of evolution was not widely accepted because, of lack of sufficient evidence. Modem evolutionary theory began in the late 1920s and early 1930s. Some scientists proved that the theory of natural selection and Mendelian genetics are the same ideas just as Darwin had proposed.