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Science 24 May 2002:
Vol. 296. no. 5572, pp. 1384 - 1385
DOI: 10.1126/science.296.5572.1384
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PALEONTOLOGY:
Reversals Reveal Pitfalls in Spotting Ancient and E.T. Life

Richard A. Kerr

Analyses of a martian meteorite sparked a search for geological markers that record the existence of life from long ago-and perhaps from far away-but mounting failures point up the difficulties. In this issue of Science (p. 1448), for example, two geologists challenge a claim that life existed 3.85 billion years or more ago. The debate highlights the growing realization that as analyses become ever more high-tech, relying on tinier samples and subtler traces, it becomes more important to understand the environment in which a presumed biomarker formed.

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Science. ISSN 0036-8075 (print), 1095-9203 (online)