Ecosystem Collapse in Pleistocene Australia and a Human Role in Megafaunal Extinction

doi:10.1126/science.1111288

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Ecosystem Collapse in Pleistocene Australia and a Human Role in Megafaunal Extinction

Gifford H. Miller,¹ Marilyn L. Fogel,² John W. Magee,³ Michael K. Gagan,⁴ Simon J. Clarke,⁵ Beverly J. Johnson⁶

Most of Australia's largest mammals became extinct 50,000 to45,000 years ago, shortly after humans colonized the continent.Without exceptional climate change at that time, a human causeis inferred, but a mechanism remains elusive. A 140,000-yearrecord of dietary ${delta}$ ¹³C documents a permanent reduction in foodsources available to the Australian emu, beginning about thetime of human colonization; a change replicated at three widelyseparated sites and in the marsupial wombat. We speculate thathuman firing of landscapes rapidly converted a drought-adaptedmosaic of trees, shrubs, and nutritious grasslands to the modernfire-adapted desert scrub. Animals that could adapt survived;those that could not, became extinct.

¹ INSTAAR and Geological Sciences, University of Colorado, Boulder, CO 80309–0450 USA.
² Geophysical Laboratory, Carnegie Institution of Washington, 1051 Broad Branch Road, Washington, DC 20015, USA.
³ Department of Earth and Marine Sciences, Australian National University, Canberra, ACT 0200, Australia.
⁴ Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia.
⁵ Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia.
⁶ Department of Geology, Bates College, Lewiston, ME 04240–6028, USA.

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PERSPECTIVES ANTHROPOLOGY: The Remaking of Australia's Ecology: Christopher N. Johnson (8 July 2005)
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