  Human language emerged abruptly. Diverse body forms evolved suddenly.
Seed-bearing plants spread rapidly. How do complex evolutionary innovations
arise so quickly? Resolving alternative claims remains difficult. The great
events of the past happened a long time ago. Cancer provides a model to study
evolutionary innovation. A tumor must evolve many novel traits to become an
aggressive cancer. I use what we know or could study about cancer to describe
the key processes of innovation. In general, evolutionary systems form a
hierarchy of recursive processes. Those recursive processes determine the rates
at which innovations are generated, spread and transmitted. I relate the
recursive processes to abrupt evolutionary innovation.
