For Immediate Release Media contacts: The Field Museum Greg Borzo 312/665-7106 gborzo@fieldmuseum.org Study resolves doubt about origin of Earth's oldest rocks, possibility of finding traces of ancient life CHICAGO—Experiments led by Nicolas Dauphas of the University of Chicago and Chicago's Field Museum have validated some controversial rocks from Greenland as the potential site for the earliest evidence of life on Earth. "The samples we have studied are extremely controversial," said Dauphas, an Assistant Professor in Geophysical Sciences at the University of Chicago and a Field Museum Associate. Some scientists have claimed that these rocks from Greenland's banded iron formations contain traces of life that push back the biological record of life on earth to 3.85 billion years ago. Others, however, dismiss the claim. They argue that the rocks originally existed in a molten state, a condition unsuitable for the preservation of evidence for life. "My results show unambiguously that the rocks are sediment deposited at the bottom of an ocean," Dauphas said. "This is an important result. It puts the search for life on the early Earth on firm foundations." Dauphas will announce his findings in the Dec. 17 issue of the journal Science. His co-authors are Meenakshi Wadhwa and Philip Janney of Chicago's Field Museum, Andrew Davis of the University of Chicago, and Mark van Zuilen and Bernard Marty of France's Centre de Recherches Petrographiques et Geochimiques. The oldest-known microfossils, which come from Australia and are themselves disputed, are more than 3.4 billion years old. Scientists have now turned their attention to Greenland for evidence of even older biological activity. Continue>>