title: Extremophiles may be irrelevant to the origin of life.
abstract: In recent years, Bacteria and Archaea have been discovered living in practically every conceivable terrestrial environment, including some previously thought to be too extreme for survival. Exploration of our solar system has revealed a number of extraterrestrial bodies that harbor environments analogous to many of the terrestrial environments in which extremophiles flourish. The recent discovery of more than 105 extrasolar planets suggests that planetary systems are quite common. These three findings have led some to speculate that life is therefore common in the universe, as life as we know it can seemingly survive almost anywhere there is liquid water. It is suggested here that while environments capable of supporting life may be common, this does not in itself support the notion that life is common in the universe. Given that interplanetary transfer of life may be unlikely, the actual origin of life may require specific environmental and geological conditions that may be much less common than the mere existence of liquid water.
authors.affiliation: Geosciences Research Divison, Scripps Institution of Oceanography, La Jolla, California 92093-0212, USA. hcleaves@ucsd.edu
authors.forename: H James
authors.initials: HJ
authors.lastname: Cleaves
authors.forename: John H
authors.initials: JH
authors.lastname: Chalmers
mesh_terms: D001105:Archaea; D001419:Bacteria; D018559:Exobiology; D000069497:Origin of Life