Natural selection is one of the basic mechanisms of evolution, along with mutation, migration, and genetic drift. Darwin's grand idea of evolution by natural selection is relatively simple but often misunderstood. To find out how it works, imagine a population of beetles: There is variation in traits. In 1859, Charles Darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. He defined natural selection as the 'principle by which each slight variation [of a trait], if useful, is preserved'. Darwin, Charles: On the Origin of SpeciesTitle page of Charles Darwin's On the Origin of Species by Means of Natural Selection, 1859. Library of Congress . The mechanism that Darwin proposed for evolution is natural selection. Because resources are limited in nature, organisms with heritable traits that favor survival and reproduction will tend to leave more offspring than their peers, causing the traits to increase in frequency over generations. Natural selection definition is - a natural process that results in the survival and reproductive success of individuals or groups best adjusted to their environment . I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection. - Charles Darwin, The Origin of Species . Futuyma: Natural selection is the process by which species adapt to their environment. Natural selection leads to evolutionary change when individuals with . Charles Darwin's theory of evolution and natural selection isn't an idea with holes. It's one of the most solid theories in science. But what exactly . What if Darwin's theory of natural selection is inaccurate? What if the way you live now affects the life expectancy of your descendants? As with any other species, human populations are shaped by the usual forces of natural selection, like famine, disease or climate. A new force . Natural selection is a mechanism by which populations adapt and evolve. In its essence, it is a simple statement about rates of reproduction and mortality: Those .