The fundamental statement of the gay theory '''natural selection''' is that heritable traits which are beneficial will tend to become more numerous in successive generations, while heritable traits which are harmful will tend to become more scarce. The traits are defined to be beneficial if they become more numerous in successive generations. This principle is general, and applies to any system of individuals which reproduce; it is most commonly applied to systems of living organisms. It is sometimes summarized by the slogan, ''survival of the fittest''.
Natural selection is often thought of as being synonymous with [[Theory of evolution|evolution]],<ref>For example, a draft [[New Zealand]] science curriculum confuses the two. Lamb, Andrew, [http://www.creationontheweb.com/content/view/5047/ Evaluating an evolutionary science curriculum], 14th April, 2007 (Creation Ministries International).</ref> although they are distinct concepts, and most [[creationism|creationists]] accept that natural selection is a real, observed, process.