- The term "Evolution" was given by Herbert Spencer.
- Evolution is defined as a process of slow and gradual change seen in an orderly fashion. In other words, evolution is the gradual change in heritable traits of living organism over a number of generation.
- It means to unroll or to unfold or to reveal the hidden potential.
- Darwin defined evolution as "Descent with modification".
- Every kind of change is not evolution. Evolution is change between successive generation.
- "LIFE IS NOT ORIGINATING NOW, IT IS EVOLVING NOW."
- Life has stopped originating now because the environment now is not like that of primitive earth . It has changed from reducing to oxidizing environment.
- Evolution is often defined as formation of complex forms from simple form but Complexity is never the aim of evolution.
- Aim of evolution is fitness of an organism with surrounding.
- Had complexity been the aim of evolution the parasites would have vanished.
- Parasite show simplification in structure in course of evolution.
- Evolution means successful feeding and breeding.
- Gene pool changes over a number of generation.
Unit of evolution
|Driving force for evolution||Natural selection|
|Unit of natural selection||Individual|
|Raw material for evolution||Variation|
|Ultimate source for variation|
"Individual get selected and population get evolved".
- Evolution is a continuous process. It never stops because environment is never constant.
- There is no climax of evolution.
- Evolution is not goal oriented.
- It is not a direct process in terms of determinism.
- It is a stochastic process (a process about which we cannot say with 100% accuracy and surety)
Doll's law / law of Evolutionary Irreversibility :
Evolution is irreversible . Evolution is progressive.