History of Theories of Mass Extinction by Meteorite Impact and Alternative Causes

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Dr. William Glen, who is undertaking this project under the direction of Dr. Weart, is continuing his study, supported under previous NSF grants, of a series of current interdisciplinary debates that were prompted by the discovery of chemical evidence suggesting a meteorite impact at the time of mass extinction in the fossil record 65 million years ago. Such extinctions, subsequently postulated as periodic, were explained by three new alternative astronomical hypotheses, all designed to cyclically shower the earth with comets. A number of additional hypotheses have also been advanced that address various aspects of the biosphere, atmosphere, and lithosphere bearing on mass extinctions. Dr. Glen has produced a stage-specific data base including a large number of oral history interviews of the participants of the debates over the development of these competing theories. These interviews and other documentary data have aided in understanding how perceptions form and alter as arguments evolve. They also serve in assessing various models of science and have lent themselves to the analysis and taxonomy of the upheaval resulting from these debates. The interviewing and collecting of primary historical materials has been essentially completed. Dr. Glen is currently completing a major survey of members of 9 professional societies related to the theories under debate. Under this grant, he is analyzing the data he has collected to date, conducting a few focussed followup interviews, examining the "pre-history" of these debates, and preparing a final study of this history. These results, when published, will provide major source material for the history, philosophy and social science of science.