Journal ArticleDOI
The habitat and nature of early life
Euan G. Nisbet,Norman H. Sleep +1 more
TLDR
It is possible that early life diversified near hydrothermal vents, but hypotheses that life first occupied other pre-bottleneck habitats are tenable (including transfer from Mars on ejecta from impacts there).Abstract:
Earth is over 4,500 million years old. Massive bombardment of the planet took place for the first 500–700 million years, and the largest impacts would have been capable of sterilizing the planet. Probably until 4,000 million years ago or later, occasional impacts might have heated the ocean over 100 °C. Life on Earth dates from before about 3,800 million years ago, and is likely to have gone through one or more hot-ocean 'bottlenecks'. Only hyperthermophiles (organisms optimally living in water at 80–110 °C) would have survived. It is possible that early life diversified near hydrothermal vents, but hypotheses that life first occupied other pre-bottleneck habitats are tenable (including transfer from Mars on ejecta from impacts there). Early hyperthermophile life, probably near hydrothermal systems, may have been non-photosynthetic, and many housekeeping proteins and biochemical processes may have an original hydrothermal heritage. The development of anoxygenic and then oxygenic photosynthesis would have allowed life to escape the hydrothermal setting. By about 3,500 million years ago, most of the principal biochemical pathways that sustain the modern biosphere had evolved, and were global in scope.read more
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Molecular mechanisms of photosynthesis
TL;DR: This chapter discusses the organization and structure of Photosynthetic Systems, as well as the history and development of Photosynthesis, and the origins and evolution of photosynthesis.
Journal ArticleDOI
Oxidative stress in marine environments: biochemistry and physiological ecology.
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Water on Mars
TL;DR: In this paper, the amount of water outgassed from Mars by impact erosion and hydrodynamic escape is estimated to be between 6 to 160 m. The two sets of estimates may be reconciled if early in its history, Mars lost part of its atmosphere.
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THE EARLY HISTORY OF ATMOSPHERIC OXYGEN: Homage to Robert M. Garrels
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Journal ArticleDOI
The origin and evolution of model organisms.
TL;DR: The phylogeny and timescale of life are becoming better understood as the analysis of genomic data from model organisms continues to grow and the emphasis on historical patterns is helping to bridge barriers among organism-based research communities.
References
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A Molecular View of Microbial Diversity and the Biosphere
TL;DR: Over three decades of molecular-phylogenetic studies, researchers have compiled an increasingly robust map of evolutionary diversification showing that the main diversity of life is microbial, distributed among three primary relatedness groups or domains: Archaea, Bacteria, and Eucarya.
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Habitable zones around main sequence stars
TL;DR: The results suggest that mid-to-early K stars should be considered along with G stars as optimal candidates in the search for extraterrestrial life.
Journal ArticleDOI
Origin of life: The RNA world
TL;DR: L'auteur postule un systeme, auto-replicatif a l'origine uniquement compose de molecules d'ARN.