Is There Such a Thing as a Biosignature?

Malaterre, Christophe; ten Kate, Inge Loes; Baqué, Mickael; Debaille, Vinciane; Grenfell, John Lee; Javaux, Emmanuelle J.; Khawaja, Nozair; Klenner, Fabian; Lara, Yannick J.; McMahon, Sean; Moore, Keavin; Noack, Lena; Patty, C.H. Lucas; Postberg, Frank

doi:10.1089/ast.2023.0042

Cited by 11 publications

(2 citation statements)

References 111 publications

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“…Apart from the chemical and mineralogical considerations (13,(16)(17)(18), one key emphasis of the studies arguing for and against the biological origin of Archaean Eon organic structures involves an extensive morphological comparison with extant prokaryotes or abiotically formed minerals (8,9,19,20). Cell morphology among extant organisms is maintained by a plethora of intracellular processes and is determined by the information encoded in their genome (21).…”

Section: Introductionmentioning

confidence: 99%

On the nature of the earliest known lifeforms

Kanaparthi

Lampe

Zhu

et al. 2021

Preprint

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Oldest known microfossils were known to have the most complex of morphologies among prokaryotes. Given the morphology of an organism is governed by information encoded in its genome, it was proposed that these primitive organisms most likely possessed complex molecular biological processes. Here we worked with bacterial protoplasts under environmental conditions of Archaean earth and reproduced morphologies of every known microfossil and associated structures. Contrary to the current presumption, our work suggest that complex morphologies of these microfossils could be explained not by presence but by complete absence of molecular biological mechanisms. Environmental conditions and architecture of the cell membrane are the only factors that determined the morphology of these organisms. Based on our observations we present a case for reinterpretation of Archaean microfossils as protocells that were devoid of complex molecular biological processes rather than annotating them to a particular phylogenetic group of extant bacteria.

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Section: Introductionmentioning

confidence: 99%

On the nature of the earliest known lifeforms

Kanaparthi

Lampe

Zhu

et al. 2021

Preprint

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“…Without some consensus on this basic question, the term may be positively unhelpful, obscuring more than it reveals about the quality and finality of the evidence to which it is applied. Given recent calls for clearer communication about life detection (Green et al, 2021;Malaterre et al, 2023), now seems an opportune moment to revisit and reunify the disparate definitions of a biosignature. To provide a motivating example of this disparity, the often-cited definition from the NASA Astrobiology Roadmap (Des Marais et al, 2003) states that: "A biosignature is an object, substance, and/or pattern whose origin specifically requires a biological agent" (p.234, emphasis added).…”

Section: Introductionmentioning

confidence: 99%

The Call for a New Definition of Biosignature

Gillen,

Jeancolas,

McMahon

et al. 2023

Astrobiology

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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 contextsfrom 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.

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Can Chirality Answer Whether We Are Alone?

Bagdžiūnas

2024

Chirality

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Detecting biosignatures of life in extraterrestrial environments remains one of the primary objectives of scientific inquiry. Currently, both remote and direct detection methods are primarily aimed at identifying key molecular classes fundamental to terrestrial biology. However, a more universally applicable spectroscopic approach could involve searching for homochiral molecules. Thus, this perspective delves into the significance of homochirality as a critical factor in the origin of life. Without homochirality, the formation of self‐recognizing and self‐replicating complex molecules would be hindered. The various hypotheses concerning the origin of homochiral molecules have been explored and analyzed within this context. This perspective emphasizes the potential for discovering extraterrestrial microscopic life through the detection of homochiral molecules using chirodetecting methods such as chromatography and chiroptical spectroscopy or circular polarimetry as a promising remote technique. This discussion highlights the importance of homochirality in the broader search for life beyond Earth and underscores the need for innovative methodologies and instrumentation in astrobiological research. These techniques can be an effective method for detecting homochirality on future planetary missions.

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Is There Such a Thing as a Biosignature?

Cited by 11 publications

References 111 publications

On the nature of the earliest known lifeforms

On the nature of the earliest known lifeforms

The Call for a New Definition of Biosignature

Can Chirality Answer Whether We Are Alone?

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