Q.Define the term: Organic evolution

The word evolution derives from the Latin e (from) and volvere (to roll), meaning the act of unrolling or unfolding — a fitting description of a process that brings about orderly change from one form to another, such that descendants become progressively different from their ancestors. Organic evolution is defined more precisely as the slow, gradual, continuous and irreversible set of changes through which today's complex forms of life developed from simpler, pre-existing ancestral forms. Charles Darwin summarised the idea in his own famous phrase: evolution is 'descent with modification'. Before Darwin's own theory of natural selection, Lamarck had already proposed that traits acquired during an organism's lifetime — in response to internal drives, environmental change, new needs, and the use or disuse of organs — could be passed on to the next generation, eventually giving rise to new species; this theory of inheritance of acquired characters is covered in its own dedicated entry (Lamarckism), and its experimental refutation by August Weismann is covered under the Theory of Continuity of the Germplasm.