Evolution How do new and different species develop? How do existing species change over time? The answer to these questions is found through the process of evolution. According to Monroe W. Strickberger, a professor at the University of Missouri in St. Louis, evolution is defined as, "Genetic changes in populations of organisms through time that lead to differences among them" (519). Evolution has many mechanisms through which these genetic changes occur. One of the most important of these mechanisms is natural selection. Before the theory of natural selection was proposed, the most prominent theory on evolution was that of Jean Baptiste de Lamarck. Lamarck's th