Research Article
No access
Published Online: 11 January 2022

Habitability Is Binary, But It Is Used by Astrobiologists to Encompass Continuous Ecological Questions

Publication: Astrobiology
Volume 22, Issue Number 1

Abstract

The term “habitability” is pervasive throughout the space sciences and astrobiology literature and is broadly used to describe an environment's ability to support life. Here, we argue that, while it is fundamentally a binary matter whether an organism can persist in an environment or not, these binary assessments lead to continuous ecological measurements that are often collected under the umbrella term “habitability” by astrobiologists. Although the use of habitability in this way has provided a framework for those studying the potential of environments to support life, including comparative analyses between terrestrial and extraterrestrial environments, it can also generate confusion and limit interdisciplinary understanding. Namely, differing ecological metrics used as proxies for habitability can yield differing conclusions depending upon the metrics chosen. Therefore, we suggest that in this continuous sense, the terms habitable and habitability lose meaning unless the specific scientific question and biological metric chosen to address it are defined. As a corollary, the search for universal single metrics to make habitability assessments is not to be encouraged, and as we argue, attempting to do so would oversimply analyses of the ability of environments to support life.

Get full access to this article

View all available purchase options and get full access to this article.

References

Aarts G, Fieberg J, Brasseur S, et al. (2013) Quantifying the effect of habitat availability on species distributions. J Anim Ecol 82:1135–1145.
Bernhardt JR, O'Connor M, Sunday J, et al. (2020) Life in fluctuating environments. Philos Trans R Soc Lond B Biol Sci 375.
Block WM and Brennan LA (1993) The habitat concept in ornithology. Current Ornithology 11:36–91.
Bradley JA, Arndt S, Amend JP, et al. (2020) Widespread energy limitation to life in global subseafloor sediments. Sci Adv 6.
Catling DC, Krissansen-Totton J, Kiang NY, et al. (2018) Exoplanet biosignatures: a framework for their assessment. Astrobiology 18:709–738.
Chao L (2010) A model for damage load and its implications for the evolution of bacterial aging. PLoS Genet 6.
Charmantier A, McCleery RH, Cole LR, et al. (2008) Adaptive phenotypic plasticity in response to climate change in a wild bird population. Science 320:800–803.
Crits-Christoph A, Robinson CK, Barnum T, et al. (2013) Colonization patterns of soil microbial communities in the Atacama Desert. Microbiome 1.
Cockell CS, Bush T, Bryce C, et al. (2016) Habitability: a review. Astrobiology 16:89–117.
Cockell CS, Harrison JP, Stevens AH, et al. (2019a) A low-diversity microbiota inhabits extreme terrestrial basaltic terrains and their fumaroles: implications for the exploration of Mars. Astrobiology 19:284–299.
Cockell CS, Stevens AH, and Prescott R (2019b) Habitability is a binary property. Nat Astron 3:956–957.
Cohen I, Rymer A, Runyon K, Clyde B, and Neptune-Odyssey Planetary Pre-Decadal Mission Concept Study Team (2020) Neptune Odyssey: mission to the Neptune-Triton system. In AAS/Division for Planetary Sciences Meeting Abstracts 52.
Elena SF and Lenski RE (2003) Evolution experiments with microorganisms: the dynamics and genetic bases of adaptation. Nat Rev Genet 4:457–469.
Elton CS (1927) Animal Ecology. Sidgwick & Jackson, London.
Fabrizio P and Longo VD (2003) The chronological life span of Saccharomyces cerevisiae. Aging Cell 2:73–81.
Fenchel T and Finlay BJ (2003) Is microbial diversity fundamentally different from biodiversity of larger animals and plants? Eur J Protistol 39:486–490.
Gaidos E, Deschenes B, Dundon L, et al. (2005) Beyond the principle of plenitude: a review of terrestrial planet habitability. Astrobiology 5:100–126.
Golden SS and Canales SR (2003) Cyanobacterial circadian clocks—timing is everything. Nat Rev Microbiol 1:191–199.
Grasset O, Dougherty MK, Coustenis A, et al. (2013) JUpiter ICy moons Explorer (JUICE): an ESA mission to orbit Ganymede and to characterise the Jupiter system. Planet Space Sci 78:1–21.
Hall LS, Krausman PR, and Morrison ML (1997) The habitat concept and a plea for standard terminology. Wildlife Society Bulletin 25:173–182.
Harder J (1997) Species-independent maintenance energy and natural population sizes. FEMS Microbiol Ecol 23:39–44.
Heller R (2020) Habitability is a continuous property of nature. Nat Astron 4:294–295.
Hirzel AH and Le Lay G (2008) Habitat suitability modelling and niche theory. J Appl Ecol 45:1372–1381.
Hoehler TM (2007) An energy balance concept for habitability. Astrobiology 7:824–838.
Hoffmann AA, Chown SL, and Clusella-Trullas S (2013) Upper thermal limits in terrestrial ectotherms: how constrained are they? Funct Ecol 27:934–949.
Hoorn C, Wesselingh FP, ter Steege H, et al. (2010) Amazonia through time: Andean uplift, climate change, landscape evolution, and biodiversity. Science 330:927–931.
Howell SM and Pappalardo RT (2020) NASA's Europa clipper: a mission to a potentially habitable ocean world. Nat Commun 11.
Howett C, Robbins S, Holler BJ, et al. (2021) Persephone: a Pluto-system orbiter and Kuiper Belt explorer to test for a subsurface ocean. Planet Sci J 2.
Hutchinson GE (1957) Concluding remarks. Cold Spring Harbor Symposia on Quantitative Biology 22:415–427.
Irwin LN, Méndez A, Fairén AG, et al. (2014) Assessing the possibility of biological complexity on other worlds, with an estimate of the occurrence of complex life in the Milky Way Galaxy. Challenges 5:159–174.
Kasting JF and Catling D (2003) Evolution of a habitable planet. Annu Rev Astron Astrophys 41:429–463.
Kempes CP, van Bodegom PM, Wolpert D, et al. (2017) Drivers of bacterial maintenance and minimal energy requirements. Front Microbiol 8.
Kereszturi A and Noack L (2016) Review on the role of planetary factors on habitability. Orig Life Evol Biosph 46:473–486.
Lammer H, Bredehoft JH, Coustenis A, et al. (2009) What makes a planet habitable? Astron Astrophys Rev 17:181–249.
Landenmark HKE, Forgan DH, and Cockell CS (2015) An estimate of the total DNA in the biosphere. PLoS Biol 13.
LaRowe DE and Amend JP (2015) Power limits for microbial life. Front Microbiol 6.
Lenardic A and Seales J (2021) Habitability: a process versus a state variable framework with observational tests and theoretical implications. Int J Astrobiol 20:125–132.
Louca S, Polz MF, Mazel F, et al. (2018) Function and functional redundancy in microbial systems. Nat Ecol Evol 2:936–943.
Merilä J and Hendry AP (2014) Climate change, adaptation, and phenotypic plasticity: the problem and the evidence. Evol Appl 7:1–14.
Nisbet E, Zahnle K, Gerasimov MV, et al. (2007) Creating habitable zones, at all scales, from planets to mud-micro-habitats, on Earth and on Mars. Space Sci Rev 129:79–121.
Odum E (1971) Fundamentals of Ecology. Saunders, Philadelphia, PA.
Price PB and Sowers T (2004) Temperature dependence of metabolic rates for microbial growth, maintenance, and survival. Proc Natl Acad Sci USA 101:4631–4636.
Schulze-Makuch D, Méndez A, Fairén AG, et al. (2011). A two-tiered approach to assessing the habitability of exoplanets. Astrobiology 11:1041–1052.
Steffan SA, Chikaraishi Y, Currie CR, et al. (2015) Microbes are trophic analogs of animals. Proc Natl Acad Sci USA 112:15119–15124.
Ueda HR, Hayashi S, Chen W, et al. (2005) System-level identification of transcriptional circuits underlying mammalian circadian clocks. Nat Genet 37:187–192.
Whitesides GH, Oates JF, Green SM, et al. (1988) Estimating primate densities from transects in a west African rain forest: a comparison of techniques. Journal of Animal Ecology 57:345–367.
Whittaker RH, Levin SA, and Root RB (1973) Niche, habitat and ecotope. The American Naturalist 107:321–338.
Wierzchos J, Ascaso C, and McKay CP (2006) Endolithic cyanobacteria in halite rocks from the hyperarid core of the Atacama Desert. Astrobiology 6:415–422.
Xue B and Leibler S (2016) Evolutionary learning of adaptation to varying environments through a transgenerational feedback. Proc Natl Acad Sci USA 113:11266–11271.

Information & Authors

Information

Published In

cover image Astrobiology
Astrobiology
Volume 22Issue Number 1January 2022
Pages: 7 - 13
PubMed: 34756098

History

Published online: 11 January 2022
Published in print: January 2022
Published ahead of print: 8 November 2021
Accepted: 11 September 2021
Received: 22 May 2021

Permissions

Request permissions for this article.

Topics

Authors

Affiliations

Charles S. Cockell [email protected]
UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK.
Toby Samuels
Geomicrobiology Group, Centre for Applied Geoscience, University of Tübingen, Tübingen, Germany.
Adam H. Stevens
UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK.

Notes

Address correspondence to: Charles S. Cockell, UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3JZ, UK [email protected]

Metrics & Citations

Metrics

Citations

Export citation

Select the format you want to export the citations of this publication.

View Options

Get Access

Access content

To read the fulltext, please use one of the options below to sign in or purchase access.

Society Access

If you are a member of a society that has access to this content please log in via your society website and then return to this publication.

Restore your content access

Enter your email address to restore your content access:

Note: This functionality works only for purchases done as a guest. If you already have an account, log in to access the content to which you are entitled.

View options

PDF/EPUB

View PDF/ePub

Full Text

View Full Text

Media

Figures

Other

Tables

Share

Share

Copy the content Link

Share on social media

Back to Top