Morphology: An Ambiguous Indicator of Biogenicity

Abstract

This paper deals with the difficulty of decoding the origins of natural structures through the study of their morphological features. We focus on the case of primitive life detection, where it is clear that the principles of comparative anatomy cannot be applied. A range of inorganic processes are described that result in morphologies emulating biological shapes, with particular emphasis on geochemically plausible processes. In particular, the formation of inorganic biomorphs in alkaline silica-rich environments are described in detail.

Co-precipitation of silica and alkaline-earth carbonates using TEOS as silica source

“…The morphologies of the precipitates depend ARTICLE IN PRESS critically on the pH of the system. We observe pHmorphology relations for TEOS-induced biomorphs consistent with the progression seen in water glass experiments [5].…”

“…The resulting aggregates display striking structural features at many length scales, reminiscent of natural biominerals [5]. They are built in part of rodshaped nano-crystallites of the alkaline-earth carbonate, typically 200 nm in length, that adopt the usual aragonite crystal structure, evidenced by X-ray diffraction.…”

Helicoidal graphene nanoribbons: Chiraltronics

“…Note that helical nanoribbons provide a fertile ground for such effects. Both the helicoid (a minimal surface) and helical nanoribbons are ubiquitous in nature; biomolecules in particular [1][2][3][4] . A helicoid has two chiralities ( Fig.…”

La vida temprana en la Tierra y los primeros ecosistemas terrestres

“…De no estar protegida, la materia orgánica tiende a degradarse por fotoquímica (si se expone a la luz), ruptura de enlaces químicos, reciclaje biológico, maceración mecánica y disolución. Aún si se conservan fósiles, muchas veces la falta de morfologías diagnósticas para la mayoría de las bacterias y la posible existencia de morfologías abióticas similares a microbios (García-Ruiz et al, 2002, 2003 hacen de su identificación y determinación taxonómica un verdadero desafío. Sin embargo, su presencia en un adecuado contexto geológico y su asociación con estructuras biosedimentaria pueden utilizarse como criterios para establecer su biogenicidad.…”