TEMPE, ARIZONA Scientists here are grappling with the search for life, not only in space, but right here on Earth.
Nearly 600 scientists from around the world have gathered here to report on the burgeoning field of astrobiology the study of life on our home planet and elsewhere.
New studies were unveiled at the opening day of NASAs Astrobiology Institute General Meeting, held here this week at Arizona State University.
The research provides evidence that some of the most important evolutionary events in Earths history didnt just create new organisms they created new fundamental biochemical processes. Moreover, those biochemical processes evolved from other biochemical processes.
Chemical kinship
Robert Blankenship, an Arizona State University (ASU) biochemist, has found that photosynthesis and nitrogen fixation may be related to each other: photosynthesis made light energy available to life; nitrogen fixation made atmospheric nitrogen available to life.
Blankenship said there could be a kinship between these two world-altering chemical processes in Earths early biosphere. They may be related to each other because some of their key enzymes appear to have evolved from a common ancestor that might be part of a third, significantly different, biochemical process.
A critical part of the emerging evolutionary picture, Blankenship said, seems to be "horizontal gene transfer" genetic change that occurs by the exchange of genetic material between bacteria. This process allows for sudden evolutionary leaps that are perhaps not possible through gradual genetic change and natural selection, he said.
Earth and Mars: desert life link?
In other research reported here, common desert organisms here on Earth may help in the search for life elsewhere.
ASUs Ferran Garcia-Pichel said his work suggests that single-celled cyanobacteria once formed the major ecosystems of the Earth. Also, these tough, tiny critters played a major role in transforming the early Earth into the Earth we know today.
Garcia-Pichel said studies of modern desert soil crusts might help unravel the question of life on Mars.
What kind of ecosystem would have been the last to be on the surface soils of Mars? It would have been something like desert crusts today, Garcia-Pichel reported.
"So just there our chances of finding some indirect evidence of life are highest," Garcia-Pichel said. A key issue, however, is learning how to recognize possible biosignatures from any past martian ecosystems, he said.
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