  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.
