evolution...in a nut shell.

In biology, evolution is the change of traits in a population of organisms from one generation to the next. There is one major mechanism that drives evolution. That is natural selection, a process causing traits that are helpful for survival and reproduction to become more common in a population, and harmful traits to become more rare. This occurs because individuals with the beneficial traits are more likely to reproduce, so that more individuals in the next generation will inherit these traits. Darwin's Theory of Evolution is the widely held notion that all life is related and has descended from a common ancestor: the birds and the bananas, the fishes and the flowers are all related. Darwin's general theory presumes the development of life from non-life and stresses a purely naturalistic view. That is that complex creatures evolve from more simplistic ancestors naturally over time. In a nutshell, as random genetic mutations occur within an organism's genetic code, the beneficial mutations are preserved because they aid survival -- a process known as "natural selection." These beneficial mutations are passed on to the next generation. Over time, beneficial mutations accumulate and the result is an entirely different organism (not just a variation of the original, but an entirely different creature).