The Call for a New Definition of Biosignature

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The term biosignature 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 any phenomenon for which biological processes are a known possible explanation and whose potential abiotic causes have been reasonably explored and ruled out. 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.
Original languageEnglish
Pages (from-to)1228-1237
Number of pages10
JournalAstrobiology
Volume23
Issue number11
Early online date11 Oct 2023
DOIs
Publication statusPublished - 10 Nov 2023

Keywords / Materials (for Non-textual outputs)

  • Biosignatures
  • The problem of unconceived alternatives
  • Abiotic mimics
  • Confidence of life detection

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