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The Call for a New Definition of Biosignature.

Gillen, Catherine; Jeancolas, Cyrille; McMahon, Sean; Vickers, Peter

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Cat Gillen
PGR Student Doctor of Philosophy

Sean McMahon


The term has become increasingly prevalent in astrobiology literature as our ability to search for life advances. Although this term has been useful to the community, its definition is not settled. Existing definitions conflict sharply over the balance of evidence needed to establish a biosignature, which leads to misunderstanding and confusion about what is being claimed when biosignatures are purportedly detected. To resolve this, we offer a new definition of a biosignature as This definition is strong enough to do the work required of it in multiple contexts-from the search for life on Mars to exoplanet spectroscopy-where the quality and indeed quantity of obtainable evidence is markedly different. Moreover, it addresses the pernicious problem of unconceived abiotic mimics that is central to biosignature research. We show that the new definition yields intuitively satisfying judgments when applied to historical biosignature claims. We also reaffirm the importance of multidisciplinary work on abiotic mimics to narrow the gap between the detection of a biosignature and a confirmed discovery of life.


Gillen, C., Jeancolas, C., McMahon, S., & Vickers, P. (2023). The Call for a New Definition of Biosignature. Astrobiology, 23(11), 1228-1237.

Journal Article Type Article
Acceptance Date Aug 27, 2023
Online Publication Date Nov 10, 2023
Publication Date Nov 10, 2023
Deposit Date Dec 20, 2023
Publicly Available Date Dec 20, 2023
Journal Astrobiology
Print ISSN 1531-1074
Publisher Mary Ann Liebert
Peer Reviewed Peer Reviewed
Volume 23
Issue 11
Pages 1228-1237
Keywords Abiotic mimics, Biosignatures, The problem of unconceived alternatives, Confidence of life detection
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