( Ten years ago an international team of...)UCLA scientists strengthen case for life more than 3.8 billion years ago

Ten years ago, an international team of scientists reported evidence, in a controversial cover story in the journal Nature, that life on Earth began more than 3.8 billion years ago--400 million years earlier than previously thought. A UCLA professor who was not part of that team and two of the original authors will report in late July that the evidence is stronger than ever.

Craig E. Manning, lead author of the new study and a professor of geology and geochemistry in the UCLA Department of Earth and Space Sciences, painstakingly mapped an area on Akilia Island in West Greenland where ancient rocks were discovered that may preserve carbon-isotope evidence for life at the time of their formation. Manning and his co-authors--T. Mark Harrison, a UCLA professor of geochemistry, director of UCLA's Institute of Geophysics and Planetary Physics, and University Professor at the Australian National University; and Stephen J. Mojzsis, assistant professor of geological sciences at the University of Colorado, Boulder--conducted new geologic and geochemical analysis on these rocks. Their findings will be reported in the new issue of the American Journal of Science. Harrison and Mojzsis were co-authors on the Nov. 7, 1996, study in Nature.

"This paper shows, with far greater confidence than we ever had before, that these rocks are older than 3.8 billion years," said Manning, who has conducted extensive research in Greenland. "We have shown that the rocks are appropriate for hosting life.

"Everything from the basic geology to the analysis in the original report (in Nature) has been challenged," said Manning, who has expertise in areas that have become central to the debate, including the chemistry of water and the interaction of water and rock. "The chemical evidence for life has been challenged, as have been the minerals to determine whether life was present, whether the rocks have the origin that was originally attributed to them, and whether the rocks w
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Source:University of California - Los Angeles

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