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Panspermia in the context of the timing of the origin of life and microbial phylogeny

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Line, MA (2007) Panspermia in the context of the timing of the origin of life and microbial phylogeny. International Journal of Astrobiology, 6 (3). pp. 249-254. ISSN 1473-5504

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Abstract

The synthesis of physical information on early Earth (or Mars) with recent knowledge arising from microbial genomic, proteomic and phylogenetic studies, strongly indicates that there was insufficient time (∼600 000 years) for life to arise and evolve to reach the biochemical complexity evident within the Last Common Community (LCC). If recent strong evidence of fossil cyanobacteria in carbonaceous meteorites is accepted, then the LCC would have existed prior to the origin of life on Earth and the planet would then have been seeded with representatives of the three domains once it became habitable. The existence of intermittently active cyanobacteria in comets opens the possibility for the evolution of microaerobic bacterial metabolism, elements of which appear at a deep level of the microbial phylogeny, at or below the depth of the LCC. It is also notable from a panspermia perspective that recent phylogenetic evidence indicates that the Gram-positive lineage (representatives of which are endowed with long-lived radiation-resistant spores) lies at the deepest level of domain Bacteria, with Archaea and Eukarya evolving from this lineage probably before 3.6 Gigayears ago (Gya).

Item Type: Article
Keywords: panspermia; phylogeny of life
Journal or Publication Title: International Journal of Astrobiology
Publisher: Cambridge University Press
Page Range: pp. 249-254
ISSN: 1473-5504
Identification Number - DOI: 10.1017/S1473550407003813
Additional Information:

© 2007 Cambridge University Press

Date Deposited: 07 Apr 2008 14:43
Last Modified: 18 Nov 2014 03:36
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