Defining Lyfe in the Universe: From Three Privileged Functions to Four Pillars
by Stuart Bartlett 1,2,* and Michael L. Wong 3,4
1 Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
2 Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan
3 Department of Astronomy and Astrobiology Program, University of Washington, Seattle, WA 98195, USA
4 NASA Nexus for Exoplanet System Science’s Virtual Planetary Laboratory, University of Washington, Seattle, WA 98195, USA
* Author to whom correspondence should be addressed.
Life 2020, 10(4), 42; https://doi.org/10.3390/life10040042
Received: 23 March 2020 / Revised: 12 April 2020 / Accepted: 13 April 2020 / Published: 16 April 2020
(This article belongs to the Special Issue Frontiers of Astrobiology)
Abstract
Motivated by the need to paint a more general picture of what life is—and could be—with respect to the rest of the phenomena of the universe, we propose a new vocabulary for astrobiological research. Lyfe is defined as any system that fulfills all four processes of the living state, namely: dissipation, autocatalysis, homeostasis, and learning. Life is defined as the instance of lyfe that we are familiar with on Earth, one that uses a specific organometallic molecular toolbox to record information about its environment and achieve dynamical order by dissipating certain planetary disequilibria. This new classification system allows the astrobiological community to more clearly define the questions that propel their research—e.g., whether they are developing a historical narrative to explain the origin of life (on Earth), or a universal narrative for the emergence of lyfe, or whether they are seeking signs of life specifically, or lyfe at large across the universe. While the concept of “life as we don’t know it” is not new, the four pillars of lyfe offer a novel perspective on the living state that is indifferent to the particular components that might produce it.
Keywords: definition of life; origin of life; astrobiology; mechanotroph
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