Part 1 of Essay
What is Evolution? Evolution is the process by which all living things have developed from primitive organisms through changes occurring over billions of years, a process that includes all animals and plants. Exactly how evolution occurs is still a matter of debate, but there are many different theories and that it occurs ....

Part 2 of Essay
.... it occurs in a variety of forms differing in hereditary traits, that are passed from parent to offspring. By chance, some varieties prove to be ill adapted to their current environment and thus disappear, whereas others prove to be adaptive, and their numbers increase. The elimination of the unfit, or the "survival of the fittest," is known as Natural Selection because it is nature that discards or favors a particular being. Evolution takes place only when natural selection operates on apopulation of organisms c ....