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Past Research Highlights

January/February/March 2006

Overkill in Near Time: The Meaning of Prehistoric Extinctions

Paul S. Martin, University of Arizona, Department of Geosciences

Paul Martin Paul S. Martin, Emeritus Professor of the University of Arizona's Department of Geosciences and long-time resident of the Desert Laboratory (since 1957), has authored a new trade book, one part biography, two parts synthesis, entitled, Twilight of the Mammoths: Ice Age Extinctions and the Rewilding of America (University of California Press, 2005, 250 p.). In this book, Paul summarizes and updates his lifelong preoccupation with the prehistoric extinctions of mammals, birds, mollusks, and, rarely, trees in what he calls "near time" or the late Quaternary period. This volume is written in Paul's delightful narrative style. As Cornell herpetologist Harry W. Greene so aptly declares in the forward to the book: "I doubt anyone else could make standing chest-deep in extinct sloth dung sound so magical."

In the last 50,000 years, different parts of the world suffered wrenching extinctions: large marsupials in Australasia around 50-40 ka; North And South American megafauna at 13-10 ka; sloths in the Greater Antilles 5 ka and flightless birds on most oceanic islands including Madagascar, New Zealand and Hawaii in the late Holocene (last 2000 years). Unlike earlier extinctions in the fossil record, the timing and intensity of those in the late Quaternary reflect the spread of, and apparently were caused by our species. Paul recounts experiences, his own and those of students and colleagues, in the Grand Canyon, elsewhere in the American Southwest, and in other lands that led to his conclusion.

These prehistoric losses had the effect of "hardening" the historic fauna, diminishing our perception of the phenomenon of human-driven extinctions. In the absence of proboscideans, ground sloths, glyptodonts and giant tortoises, to name a few of those exterminated in near time, the traditional baseline for evaluating human impact is severely attenuated, reducing or depleting the standard by which historic human impact is judged.

In the final chapter, entitled "Resurrection", Paul makes the case for near-time restoration of species lost, or at least their functional equivalents. Paul endorses a new and realistic concept of 'rewilding' - bringing elephants, cheetahs, and lions out of captivity to run free in parts of North America - to give these animals a shot at surviving human land use and climate change, and thus maximize chances for their lineages to resume 'natural' evolution in near time (see also Donlan et al. 2005).

Donlan, C. J., H. W. Greene, J. Berger, C. E. Bock, J. H. Bock, D. A. Burney, J. A. Estes, D. Forman, P. S. Martin, G. W. Roemer, F. A. Smith, M. E. Soulé. 2005. Re-wilding North America. Nature 436: 913-914.

Cover image of Twilight of the Mammoths: Ice Age Extinctions and the Rewilding
of America.

Paul's book can be ordered directly from the University of California Press at or from many popular book outlets.

For more information contact:
Paul Martin (

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