• 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.

"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.