Survival machines that can simulate the future are one jump ahead of survival machines that who can only learn of the basis of trial and error. The trouble with overt trial is that it takes time and energy. The trouble with overt error is that it is often fatal.... The evolution of the capacity to simulate seems to have culminated in subjective consciousness. Why this should have happened is, to me, the most profound mystery facing modern biology.

Ch. 4. The Gene machine - The Selfish Gene (1976, 1989)