Charles Darwin was a British scientist of the 19th century, who first theorized that all species evolved from others. Within his body of work, he proposed ideas which have come to be known as the Theory of Evolution, which is supported by Natural Selection. Darwin first published these theories in a volume called On the Origin of Species in 1859.
In effect, the Theory of Evolution states that all living things have evolved from other living things. All living things can trace their roots to other species that came before them.
"Natural selection" describes the way species adapt to their environment, making them more able to survive - and evolve - as the environment changes. An example of that adaptation would be the way human beings have evolved to be taller or to walk upright. Another example would be that smaller animals considered as food by larger animals, have evolved to run faster than their predators.
"Survival of the fittest" is a phrase also used to describe natural selection. Some people credit Darwin with the phrase. However, while Darwin did adopt that phrase in a later edition of his Origin of Species series, the person who first used the phrase was a colleague of Darwin's, British philosopher Herbert Spencer.
Darwin's theories have stood the test of time, and are used today as the basis for several health and medical explanations:
- Bacteria and viruses which cause people to get sick and die have evolved to adapt to their hosts. Examples are nosocomial infections like MRSA and C.Diff, or illnesses and pandemics like H1N1 swine flu.
- Personalized medicine, and the Human Genome Project, are both partially based on Darwin's theories. The genetic code of human beings is altered by traits acquired by humans over many generations.