In accordance with the law of accelerating returns, paradigm shift (also called innovation) turns the S-curve of any specific paradigm into a continuing exponential. A new paradigm, such as three-dimensional circuits, takes over when the old paradigm approaches its natural limit, which has already happened at least four times in the history of computation (electromechanical, relay, vaccum tube and transistor, we’re in the integrated circuit era).
In such nonhuman species as apes, the mastery of a toolmaking or-using skill by each animal is characterized by an S-shaped learning curve that ends abruptly; human-created technology, in contrast, has followed an exponential pattern of growth and acceleration.
— Extracted from The Singularity is Near, by Ray Kurzweil. Chapter 2: A theory of technology evolution