Natural selection is the process by which species adapt to their environment. Natural selection leads to evolutionary change when individuals with certain characteristics have a greater survival or reproductive rate than other individuals in a population and pass on these inheritable genetic characteristics to their offspring. Simply put, natural selection is a consistent difference in survival and reproduction between different genotypes, or even different genes, in what we could call reproductive success. A genotype is a group of organisms sharing a specific genetic makeup. The reason that natural selection is important is that it’s the central idea, stemming from Charles Darwin and Alfred Russel Wallace, that explains design in nature. It is the one process that is responsible for the evolution of adaptations of organisms to their environment. Darwin’s book On the Origin of Species by Means of Natural Selection caused quite a stir when it appeared in 1859. Evidence to support evolution and natural selection, of course, has accumulated over time, and now science accepts that evolution is a fact and that natural selection explains very well how adaptive evolution takes place.