The theory of evolution by natural selection is a key concept in the study of biology. It holds that all living things share a common ancestor and that different species are the result of changes to geographically distinct populations over long periods of time caused by the application of natural forces, the inability of populations to grow indefinitely without boundary, the likelihood that only individuals that are 'fit' to survive in a particular environment will live long enough to have offspring, and the fact that all individuals in a population have variations.
Since it was first suggested in the 19th century independently by Charles Darwin and Alfred Russell Wallace, evolution has obtained more and more scientific support and is generally regarded to be true by the scientific community. Among the scientific findings that support evolution were the finding that the earth is very old (on the order of 4-5 billion years), that the mechanism of genetics allows beneficial variations to be passed from generation to generation without being "averaged out", and that DNA from organisms that appear to be closely related (such as gorillas and chimpanzees, or people of the same nationality) have more genes in common than organisms that do not appear to be closely related (such as chimpanzees and bullfrogs, or Australian Aborigines and Native Americans).
In medicine, evolution is used to explain phenomena such as the epidemiology of genetic diseases and bacterial resistance to antibiotics.
House refers to evolution in many episodes. In No More Mr. Nice Guy, he suggests that the patient, who never gets angry, could not be possible if evolution was correct.