From systems chemistry to systems astrobiology: life in the universe as an emergent phenomenon

Abstract

Although astrobiology is a science midway between the life and physical sciences, it has surprisingly remained largely disconnected from recent trends in certain branches of both life and physical sciences. We discuss potential applications to astrobiology of approaches that aim at integrating rather than reducing. Aiming at discovering how systems properties emerge has proved valuable in chemistry and in biology. The systems approach should also yield insights into astrobiology, especially concerning the ongoing search for alternative abodes for life. This is feasible since new data banks in the case of astrobiology – considered as a branch of biology – are of a geophysical/astronomical kind, rather than the molecular biology data that are used for questions related firstly, to genetics in a systems context and secondly, to biochemistry for solving fundamental problems, such as protein or proteome folding. By focusing on how systems properties emerge in astrobiology we consider the question: can life in the universe be interpreted as an emergent phenomenon? In the search for potential habitable worlds in our galactic sector with current space missions, extensive data banks of geophysical parameters of exoplanets are rapidly emerging. We suggest that it is timely to consider life in the universe as an emergent phenomenon that can be approached with methods beyond the science of chemical evolution – the backbone of previous research in questions related to the origin of life. The application of systems biology to incorporate the emergence of life in the universe is illustrated with a diagram for the familiar case of our own planetary system, where three Earth-like planets are within the habitable zone (HZ) of a G2 V (the complete terminology for the Sun in the Morgan–Keenan system) star. We underline the advantage of plotting the age of Earth-like planets against large atmospheric fraction of a biogenic gas, whenever such anomalous atmospheres are discovered in these worlds. A prediction is made as to the nature of the atmospheres of the planets that lie in the stellar HZs.

Aerobically respiring prokaryotic strains exhibit a broader temperature–pH–salinity space for cell division than anaerobically respiring and fermentative strains

“…Entire metabolic networks, for example, could be considered in order to build a fuller understanding of how energy transduction affects habitability [16]. Moreover, systems approaches (including 'omics' methods [92]) are likely to play an important future role in improving our knowledge of the physico-chemical limits for microbial cell division [93]. Such approaches are particularly necessary to advance our understanding of how diverse stress parameters (and physiological adaptations to them) interact, and how these interactions shape the biophysical boundaries for life on the Earth.…”

On the parallels between cosmology and astrobiology: a transdisciplinary approach to the search for extraterrestrial life

“…As mentioned above, astrobiological research has not only one but two objects of study, life and the universe. Astrobiology is based on the perspective that life should be treated as a cosmic phenomenon (Darling, 2001; Ward, 2005; Dick, 2012; Chela-Flores, 2013; Santos & Alabi, 2013). When taking into account not only the interactions of living organisms with each other but also with the planet and other celestial bodies and astrophysical events, it is clear that terrestrial life is itself an object of astrobiological research.…”

A lander mission to probe subglacial water on Saturn׳s moon Enceladus for life

“…One of the most intensely debated problems in evolutionary biology, aside from the enigma posed by the origin of life itself, is the existence of universal laws governing the emergence and subsequent evolution of biological complexity through natural selection [12,13]. While the force of natural selection in driving adaptation of species to changing environments is undisputed, most evolutionary biologists freely admit that they can hardly give a comprehensive account of the major transitions that occurred during the history of life on Earth, such as, for instance, the bridging of prebiotic, protocellular and cellular evolution, multiple endosymbiosis events in ancient microbes, the emergence of eukaryotic and multicellular organisms and the sudden appearance of complex body plans in the Cambrian.…”