title: The Physical, Chemical and Physiological Limits of Life.
abstract: Life on Earth displays an incredible diversity in form and function, which allows it to survive not only physical extremes, but also periods of time when it is exposed to non-habitable conditions. Extreme physiological adaptations to bridge non-habitable conditions include various dormant states, such as spores or tuns. Here, we advance the hypothesis that if the environmental conditions are different on some other planetary body, a deviating biochemistry would evolve with types of adaptations that would manifest themselves with different physical and chemical limits of life. In this paper, we discuss two specific examples: putative life on a Mars-type planet with a hydrogen peroxide-water solvent and putative life on a Titan-type planetary body with liquid hydrocarbons as a solvent. Both examples would have the result of extending the habitable envelope of life in the universe.
authors.affiliation: School of the Environment, Washington State University, Pullman, WA 99163, USA. dirksm@wsu.edu.|Center for Astronomy and Astrophysics, Technical University Berlin, Berlin 10623, Germany. dirksm@wsu.edu.
authors.forename: Dirk
authors.initials: D
authors.lastname: Schulze-Makuch
authors.affiliation: Department of Physics, University of Leipzig, Linnéstraße 5, Leipzig 04103, Germany. aschulzemakuch@gmail.com.
authors.forename: Alexander
authors.initials: A
authors.lastname: Schulze-Makuch
authors.affiliation: Center for Astronomy and Astrophysics, Technical University Berlin, Berlin 10623, Germany. joophoutkooper@gmail.com.
authors.forename: Joop M
authors.initials: JM
authors.lastname: Houtkooper
keywords: Mars; Titan; adaptation; extreme environments; physiology