SELF STUDY PAGE ON WHAT IS EVOLUTION
The word "evolution" in its broadest sense refers to change or growth that occurs in a particular order.
Greek and medieval references to "evolution" use it as a descriptive term for a state of nature, in which everything in nature has a certain order or purpose. This is a teleological view of nature. For example, Aristotle classified all living organisms hierarchically in his great scala naturae or Great Chain of Being, with plants at the bottom, moving through lesser animals, and on to humans at the pinnacle of creation, each becoming progressively more perfect in form.
Evolution by natural selection is a theory about the process of change.
Evolution by natural selection works on three principles: variation (within a given generation there will be variation in traits, some that aid survival and reproduction and some that don’t, and some that have a genetic basis and some that don’t); competition (there will be limited resources that individuals must compete for, and traits that aid survival and reproduction will help in competition); and heritability (only traits that aid survival and reproduction and have a genetic basis can passed onto future generations).