The energy expansions of evolution

Judson, Olivia

doi:10.1038/s41559-017-0138

Cited by 84 publications

(74 citation statements)

References 164 publications

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“…We end by cautioning that our proposed methodology is by no means complete, since im- [53,83,99]. We also wish to point out that we have altogether neglected second-order effects in this study.…”

Section: Discussionmentioning

confidence: 95%

Physical constraints on the likelihood of life on exoplanets

Lingam

Loeb

2017

International Journal of Astrobiology

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One of the most fundamental questions in exoplanetology is to determine whether a given planet is habitable. We estimate the relative likelihood of a planet's propensity towards habitability by considering key physical characteristics such as the role of temperature on ecological and evolutionary processes, and atmospheric losses via hydrodynamic escape and stellar wind erosion. From our analysis, we demonstrate that Earth-sized exoplanets in the habitable zone around M-dwarfs seemingly display much lower prospects of being habitable relative to Earth, owing to the higher incident ultraviolet fluxes and closer distances to the host star. We illustrate our results by specifically computing the likelihood (of supporting life) for the recently discovered exoplanets, Proxima b and TRAPPIST-1e, which we find to be several orders of magnitude smaller than that of Earth.

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Section: Discussionmentioning

confidence: 95%

Physical constraints on the likelihood of life on exoplanets

Lingam

Loeb

2017

International Journal of Astrobiology

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“…There are sufficient grounds to conclude that the buildup of O 2 in the atmosphere may have constituted a rate-limiting step insofar the development of complex life is concerned on other worlds (Knoll, 1985;Judson, 2017). Yet, it should also be recognized that similar environmental conditions and evolutionary trajectories for complex life need not prevail on all worlds.…”

Section: Oxygen and Complex Lifementioning

confidence: 99%

Colloquium: Physical constraints for the evolution of life on exoplanets

Lingam

Loeb

2019

Rev. Mod. Phys.

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Recently, many Earth-sized planets have been discovered around stars other than the Sun that might possess appropriate conditions for life. The development of theoretical methods for assessing the putative habitability of these worlds is of paramount importance, since it serves the dual purpose of identifying and quantifying what types of biosignatures may exist and determining the selection of optimal target stars and planets for subsequent observations. This Colloquium discusses how a multitude of physical factors act in tandem to regulate the propensity of worlds for hosting detectable biospheres. The focus is primarily on planets around low-mass stars, as they are most readily accessible to searches for biosignatures. This Colloquium outlines how factors such as stellar winds, the availability of ultraviolet and visible light, the surface water and land fractions, stellar flares, and associated phenomena place potential constraints on the evolution of life on these planets.

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“…Over the past several decades, perspectives on eukaryogenesis have undergone a significant transformation [1]. Mitochondria are now thought to have been present in the eukaryote common ancestor [2,3], and the broad outlines of eukaryote lineage origin have increasingly come to include the concept of symbiosis [4][5][6][7]. Both the host lineage and the mitochondrial endosymbiont contributed to the eukaryote origin.…”

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confidence: 99%

Archaeal Histone Contributions to the Origin of Eukaryotes

Brunk

Martin

2019

Trends in Microbiology

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The eukaryotic lineage arose from bacterial and archaeal cells that underwent a symbiotic merger. At the origin of the eukaryote lineage, the bacterial partner contributed genes, metabolic energy, and the building blocks of the endomembrane system. What did the archaeal partner donate that made the eukaryotic experiment a success? The archaeal partner provided the potential for complex information processing. Archaeal histones were crucial in that regard by providing the basic functional unit with which eukaryotes organize DNA into nucleosomes, exert epigenetic control of gene expression, transcribe genes with CCAAT-box promoters, and a manifest cell cycle with condensed chromosomes. While mitochondrial energy lifted energetic constraints on eukaryotic protein production, histone-based chromatin organization paved the path to eukaryotic genome complexity, a critical hurdle en route to the evolution of complex cells. Eukaryotes from Prokaryotes: Symbiotic Contributions HighlightsThe last common ancestor of eukaryotes had mitochondria, pointing to hostsymbiont interactions at eukaryote origin. Mitochondria contributed energy, genes, and membranes to the eukaryotic lineage. What did the archaeal host contribute?Recent metagenomic studies propose that close relatives of the archaeal host exist that are 'complex' (phagocytosing) and that the archaeal host brought that complexity to eukaryotes.Yet complex archaea have not been found, and there are doubts that the metagenomic archaeal data represent truly complex archaea.Alternatively, histones could have been the key archaeal contribution to eukaryote complexity.In eukaryotes, histone modifications link gene expression to the physiological state of the cell via carbon-, energy-, and nitrogen-sensing through regulators such as AMPK, GCN2, and TOR. The Archaeal ContributionSince their discovery, archaea have been implicated as relatives of the host lineage at the origin of eukaryogenesis and mitochondria [18,19]. There is now much discussion about the possibility that complex, phagocytosing archaea might be yet discovered in nature, based on metagenomic data [20][21][22]. In that view, the contribution of archaea is unequivocal: the archaeal host brought preformed complexity to the eukaryotic lineage. Indeed, the possibility that some archaea or archaeal relatives might possess a primitive cytoskeleton has been discussed for decades [23][24][25][26].

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The energy expansions of evolution

Cited by 84 publications

References 164 publications

Physical constraints on the likelihood of life on exoplanets

Physical constraints on the likelihood of life on exoplanets

Colloquium: Physical constraints for the evolution of life on exoplanets

Archaeal Histone Contributions to the Origin of Eukaryotes

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