NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Earth's early biosphereUnderstanding our own early biosphere is essential to our search for life elsewhere, because life arose on Earth very early and rocky planets shared similar early histories. The biosphere arose before 3.8 Ga ago, was exclusively unicellular and was dominated by hyperthermophiles that utilized chemical sources of energy and employed a range of metabolic pathways for CO2 assimilation. Photosynthesis also arose very early. Oxygenic photosynthesis arose later but still prior to 2.7 Ga. The transition toward the modern global environment was paced by a decline in volcanic and hydrothermal activity. These developments allowed atmospheric O2 levels to increase. The O2 increase created new niches for aerobic life, most notably the more advanced Eukarya that eventually spawned the megascopic fauna and flora of our modern biosphere.
Document ID
20040089381
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Des Marais, D. J.
(NASA Ames Research Center Moffett Field CA United States)
Date Acquired
August 21, 2013
Publication Date
May 1, 1998
Publication Information
Publication: Gravitational and space biology bulletin : publication of the American Society for Gravitational and Space Biology
Volume: 11
Issue: 2
ISSN: 1089-988X
Subject Category
Exobiology
Distribution Limits
Public
Copyright
Other
Keywords
Review
NASA Center ARC
NASA Discipline Exobiology
Review, Tutorial

Available Downloads

There are no available downloads for this record.
No Preview Available