The Story of O2 -- Kerr 308 (5729): 1730 -- Science
EARTH SCIENCE: The Story of O2 -- Kerr 308 (5729): 1730 -- Science:
"Gaseous oxygen is essential to advanced life, but Earth came with no guarantees that oxygen would abound. Researchers are piecing together life's complex involvement in oxygen's halting 3-billion-year rise
In the beginning, Earth was devoid of oxygen, and then life arose from nonlife. As that first life evolved over a billion years, it began to produce oxygen, but not enough for the life-energizing gas to appear in the atmosphere. Was green scum all there was to life, all there ever would be? Apparently, yes, unless life and nonlife could somehow work together to oxygenate the planet from the atmosphere to the deep sea.
Earth scientists are flocking to the emerging field of astrobiology to tease out the history of oxygen on Earth from a maddeningly subtle and fragmented rock record. The rise of atmospheric oxygen from nothing to abundance, they are finding, came in two big steps about 2 billion years apart. Relatively simple life probably facilitated the first step up and possibly the second, much to its own detriment but to the benefit of more complex life.
'The rise of oxygen changed the course of evolution,' says astrobiologist David Catling of the University of Bristol, U.K. 'Atmospheric oxygen was a precursor to advanced life on Earth, and, I would argue, to life elsewhere.' With the new interest in 3 billion years of oxygen history, 'there's been a great deal of progress,' says geochemist Donald Canfield of the University of Southern Denmark in Odense. 'The field has matured; it used to be a hobby area for most people. I credit NASA's [astrobiology funding] for much of that.' An invigorated field is attacking a host of big questions: When did free oxygen first appear in Earth's atmosphere? What made it appear in the first place? What held it back for so long? And what caused the second, delayed surge of oxygen that allowed advanced animals to appear?"
"Gaseous oxygen is essential to advanced life, but Earth came with no guarantees that oxygen would abound. Researchers are piecing together life's complex involvement in oxygen's halting 3-billion-year rise
In the beginning, Earth was devoid of oxygen, and then life arose from nonlife. As that first life evolved over a billion years, it began to produce oxygen, but not enough for the life-energizing gas to appear in the atmosphere. Was green scum all there was to life, all there ever would be? Apparently, yes, unless life and nonlife could somehow work together to oxygenate the planet from the atmosphere to the deep sea.
Earth scientists are flocking to the emerging field of astrobiology to tease out the history of oxygen on Earth from a maddeningly subtle and fragmented rock record. The rise of atmospheric oxygen from nothing to abundance, they are finding, came in two big steps about 2 billion years apart. Relatively simple life probably facilitated the first step up and possibly the second, much to its own detriment but to the benefit of more complex life.
'The rise of oxygen changed the course of evolution,' says astrobiologist David Catling of the University of Bristol, U.K. 'Atmospheric oxygen was a precursor to advanced life on Earth, and, I would argue, to life elsewhere.' With the new interest in 3 billion years of oxygen history, 'there's been a great deal of progress,' says geochemist Donald Canfield of the University of Southern Denmark in Odense. 'The field has matured; it used to be a hobby area for most people. I credit NASA's [astrobiology funding] for much of that.' An invigorated field is attacking a host of big questions: When did free oxygen first appear in Earth's atmosphere? What made it appear in the first place? What held it back for so long? And what caused the second, delayed surge of oxygen that allowed advanced animals to appear?"
posted by Aloyzio Achutti at 5:24 PM
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