An alternative approach for assessing biogenicity
[EN] The search for signs of life in the ancient rock record, extreme terrestrial environments, and other planetary bodiesrequires a well-established, universal, and unambiguous test of biogenicity. This is notably true for cellular remnantsof microbial life, since their relatively simple morphologi...
| Autores: | , , , |
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| Formato: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2021 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/237302 |
| Acesso em linha: | http://hdl.handle.net/10261/237302 |
| Access Level: | acceso abierto |
| Palavra-chave: | Biosignatures Biogenicity Astrobiology Early life Cellular life |
| Resumo: | [EN] The search for signs of life in the ancient rock record, extreme terrestrial environments, and other planetary bodiesrequires a well-established, universal, and unambiguous test of biogenicity. This is notably true for cellular remnantsof microbial life, since their relatively simple morphologies resemble various abiogenic microstructures that occur innature. Although lists of qualitative biogenicity criteria have been devised, debates regarding the biogenicity of manyancient microfossils persist to this day. We propose here an alternative quantitative approach for assessing thebiogenicity of putative microfossils. In this theoretical approach, different hypotheses—involving biology or not anddepending on the geologic setting—are put forward to explain the observed objects. These hypotheses correspond tospecific types of microstructures/systems. Using test samples, the morphology and/or chemistry of these systems arethen characterized at the scale of populations. Morphologic parameters include, for example, circularity, aspect ratio,and solidity, while chemical parameters could include elementary ratios (e.g., N/C ratio), isotopic enrichments (e.g.,d13C), or chirality (e.g., molar proportion of stereoisomers), among others. Statistic trends distinguishing the differentsystems are then searched for empirically. The trends found are translated into ‘‘decision spaces’’ where the differentsystems are quantitatively discriminated and where the potential microfossil population can be located as a singlepoint. This approach, which is formulated here on a theoretical level, will solve several problems associated with theclassical qualitative criteria of biogenicity. Most importantly, it could be applied to reveal the existence of cellular lifeon other planets, for which characteristics of morphology and chemical composition are difficult to predict. |
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