Evolution is a change in heritable traits over generations. Parents pass on their genes to their children, and mutations can create new genetic variations. Over time, the genetic make-up of the population can change through random chance (genetic drift) or through selection.
Selection can be either:
- Natural selection - in a world with limited resources, organisms that are more suited to the current environment and able to have more surviving offspring are more likely to pass on and spread their genes through the population. Over time, the population becomes better adapted to its environment. Natural selection has no specific 'goal' in mind.
- Artificial selection - humans, with some goal in mind, select organisms to survive or reproduce based on some traits they show.
In Creatures, natural selection can lead to a population of prolific fast-agers, because being able to reproduce early and often increases a creature's fitness (ability to have more surviving children). Players often practice artificial selection in their worlds, such as by removing creatures with mutations (such as fast-aging) they consider bad, encouraging creatures with an appearance they like to breed, introducing obstacles for the creatures like the Creatures IQ test or extra bacteria, etc. The Drozzy Norns of C1 and other similar genetic breeds attempt to speed up the process of evolution by significantly reducing individual creatures' lifespans.