Evolution by 'natural selection' suggests that all life is related and has descended from a common ancestor and that complex creatures evolve from more simplistic ancestors naturally over time. Beneficial random genetic mutations are preserved if they aid survival and over time mutations accumulate and the result is an entirely different species. Species that fail to adapt to their surroundings will die out.

Creationism refers to the religious belief that humanity, life, the Earth, and the universe were created by a single deity pretty much in their present form at one time within the last 10,000 years or so. In Christian sects such creationism is usually based on a literal reading of Genesis 1-2. Other religions have deity-led creation myths which are quite different.