Neutral selection describes changes in the gene pool of a species that are a result of accumulated random neutral changes that do not convey any particular advantage to a species. Accordingly, neutral selection does not depend upon adaptation, fitness, and natural selection.

Evolution describes biological change over time. Scientists who study evolution argue whether natural selection or random changes have more profoundly influenced the course of evolution. According to evolutionary theory based upon natural selection, changes in the gene pool are a result of differing fitness among individuals with the population. These differences in fitness manifest result in a selective advantage or disadvantage; neutral mutations are rare. According to the neutral theory, however, most changes at the molecular level do not carry a selective advantage or disadvantage and are thus, selectively neutral. To account for wide differences in genetic make-up this would mean that the rate...