ABSTRACT
In the fall of 1959 the centennial of the publication of Darwin’s Origin of Species was celebrated at the University of Chicago. Only recently the proceedings of these meetings, including lectures, papers, panels, and general discussions, have been published in three large volumes. “Species” is defined in various ways. Perhaps the problem is best summarized by Mayr when he points out that there are three different species concepts. Evolution is the general theory that life as we know it on earth today has over a long period of time been developed by differentiation from a single or several primordial cells; descent with modification. In a population of freely interbreeding organisms in nature a change within one organism is likely to affect the population unless something happens to favor the maintainence of this particular change. The population must be so small that mutations will be maintained because the mutant genes form a significant portion of the genes in the gene pool.
