Evidences of Evolution

Evolution is the slow, progressive change that produces complexity from simple and lower organisms over millions of years on earth. This chapter surveys the different lines of evidence that support organic evolution.

Evolution and its types

Evolution can be defined as "a slow and progressive change resulting into complexity from simple and lower organisms which has taken place during millions of years on earth". There are two types of evolution:

1. Inorganic evolution: the gradual change of simpler non-living things into complex non-living things.
2. Organic evolution: the gradual change of simpler living organisms into complex living organisms.

Patterns of organic evolution

1. Divergent evolution (adaptive radiation)
2. Convergent evolution (adaptive convergence)
3. Progressive evolution
4. Retrogressive evolution
5. Parallel evolution

Divergent evolution: the evolution of a variety of species from a single ancestral species, each of which gets adapted in different ways to different environments. It is also known as adaptive radiation.

Convergent evolution: the phenomenon of acquiring similar sets of characteristics in response to adaptation to a similar environment by individuals of two or more totally unrelated groups. As a result the organisms have different body organization but possess superficial similarity. For example, the development of wings in insects, flying birds and mammals.