Darwin's theory of evolution? In simple …

According to Charles Darwin theory of evolution, there is natural variation within any population and some individuals have more favorable variations than others. The struggle for survival within population eliminates the unfit individuals and those with favorable variations survive and pass on these variations to their progeny to continue. This is also called natural selection.

Summary of Darwin's Theory of Evolution • A species is a population of organisms that interbreeds and has fertile offspring. • Living organisms have descended with modifications from species that lived before them. • Natural selection explains how this evolution has happened: — More organisms are produced than can survive because of limited resources. — Organisms struggle for the necessities of life; there is competition for resources. — Individuals within a population vary in their traits; some of these traits are heritable -- passed on to offspring. — Some variants are better adapted to survive and reproduce under local conditions than others. — Better-adapted individuals (the "fit enough") are more likely to survive and reproduce, thereby passing on copies of their genes to the next generation. — Species whose individuals are best adapted survive; others become extinct.