"Updated Formula on Alien Intelligence Suggests We Really Are Alone in the Galaxy"
Planetary scientists Robert Stern from the University of Texas at Dallas and Taras Gerya from ETH-Zurich, the two co-authors on the study, suggest that the presence of both continents and oceans, along with long-term plate tectonics, is critical for the emergence of advanced civilizations. They consequently propose the addition of two factors into the equation: the fraction of habitable planets with significant continents and oceans and the fraction of those planets with plate tectonics operating for at least 500 million years. This adjustment, however, significantly reduces the value of N in the Drake Equation.
(Via Marginal Revolution.)
