What are the factors that determine the pace of evolution?

Evolution is driven by a change in environment. A large interbreeding population in a static (unchanging) environment faces little need for the acquisition of new adaptations.

Competition for resources (whether from other members of one's own species or other) can drive evolutionary change.

The availability of new forms (random mutations) also plays a factor. Mutagens may come in the form of radiation or chemicals, and sometimes simple exposure such as viral infections. Natural selection can only operate when there is something to select. If the environment changes more rapidly than mutations can keep pace with, extinction results. Most of the species that ever existed have subsequently disappeared.

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