The Temporal Aspect of the Drake Equation and SETI

We critically investigate some evolutionary aspects of the famous Drake equation, which is usually presented as the central guide for the research on extraterrestrial intelligence. It is shown that the Drake equation tacitly relies on unverifiable and possibly false assumptions on both the physico-chemical history of our Galaxy and the properties of advanced intelligent communities. The importance of recent results of Lineweaver on chemical build-up of inhabitable planets for SETI is emphasized. Two important evolutionary effects are briefly discussed and the resolution of the difficulties within the context of the phase-transition astrobiological models sketched.