A possible solution to the Fermi Paradox, by the addition of two terms to the Drake Equation, one representing the probability of planets with sufficient land mass and oceans and one representing the probability of more than half a billion years of tectonic activity.

The work is based on the observations that a) life as we understand it needs oceans to start, that b) sufficient land mass is required for life to evolve to complex, large multicellular organisms, and that c) prolonged periods of tectonic activity appear to catalyze the evolution of large complex multicellular organisms.