A New Insight

1. Creation (Atoms -> Molecules -> Cells)
2. Evolution
3. Mutation ( caused by accident, radiation, environment )
3a. "good" mutation leads to evolution and further mutations of strain
3b. "bad" mutation leads to extinction of strain.
4. Evolution of new strain/species (previous stage = 3a)
5. Mutation
5a. ...
5b. ...

and so on.


Example for a mutation caused by environment (hypothetical):
Global warming will lead to extinction of strain or even whole species (GlobWarm-scenario comparable to impact of cosmic object (asteroid) which led to the extinction of the dinos).
A new strain will evolve which hopefully makes better use of the earth.