Sea otters, kelp forests, and the extinction of Steller's sea cow

The late Pleistocene extinction of so many large-bodied vertebrates has been variously attributed to two general causes: rapid climate change and the effects of humans as they spread from the Old World to previously uninhabited continents and islands. Many large-bodied vertebrates, especially large apex predators, maintain their associated ecosystems through top-down forcing processes, especially trophic cascades, and megaherbivores also exert an array of strong indirect effects on their communities. Thus, a third possibility for at least some of the Pleistocene extinctions is that they occurred through habitat changes resulting from the loss of these other keystone species. Here we explore the plausibility of this mechanism, using information on sea otters, kelp forests, and the recent extinction of Steller's sea cows from the Commander Islands. Large numbers of sea cows occurred in the Commander Islands at the time of their discovery by Europeans in 1741. Although extinction of these last remaining sea cows during early years of the Pacific maritime fur trade is widely thought to be a consequence of direct human overkill, we show that it is also a probable consequence of the loss of sea otters and the co-occurring loss of kelp, even if not a single sea cow had been killed directly by humans. This example supports the hypothesis that the directly caused extinctions of a few large vertebrates in the late Pleistocene may have resulted in the coextinction of numerous other species.

Reflections on the role of management in achieving a sustainable future: An interview with Tim Flannery and Dexter Dunphy

This article reports an interview with Professors Tim Flannery and Dexter Dunphy conducted during the Australian and New Zealand Academy of Management (ANZAM) Conference in December 2009. Flannery and Dunphy share their thoughts about the meaning of sustainability and what is required of business, government and individuals in responding to global environmental problems. Both professors express their passion for sustainability and clearly articulate the vital role that business and management play in achieving a sustainable future. The interview is followed by a discussion of the major themes and implications for management educators, researchers and practitioners.

Reflections on the role of management in achieving a sustainable future: An interview with Tim Flannery and Dexter Dunphy

This article reports an interview with Professors Tim Flannery and Dexter Dunphy conducted during the Australian and New Zealand Academy of Management (ANZAM) Conference in December 2009. Flannery and Dunphy share their thoughts about the meaning of sustainability and what is required of business, government and individuals in responding to global environmental problems. Both professors express their passion for sustainability and clearly articulate the vital role that business and management play in achieving a sustainable future. The interview is followed by a discussion of the major themes and implications for management educators, researchers and practitioners.

Last Glacial Maximum ages for robust humans at Kow Swamp, southern Australia

The Kow Swamp people are a fossil population of robust modern humans. We report optically stimulated luminescence (OSL) ages on sediments from Kow Swamp that are at odds with radiocarbon ages obtained previously for the site. The calibrated 14C ages place the Kow Swamp people in the period 15-9 ka. Our single aliquot OSL ages suggest that they lived around the time of the Last Glacial Maximum (LGM) between 22 and 19 ka. An LGM age for the Kow Swamp people is supported by palaeoenvironmental reconstruction. The shoreline silt, in which most of them were interred, was deposited by high lake levels between 26 and 19 ka. Few robust people were left after 19 ka when a sand lunette formed. Climate change may explain the demise of this unusual genetic population.

Explaining the Pleistocene megafaunal extinctions: models, chronologies, and assumptions

Understanding of the Pleistocene megafaunal extinctions has been advanced recently by the application of simulation models and new developments in geochronological dating. Together these have been used to posit a rapid demise of megafauna due to over-hunting by invading humans. However, we demonstrate that the results of these extinction models are highly sensitive to implicit assumptions concerning the degree of prey naivety to human hunters. In addition, we show that in Greater Australia, where the extinctions occurred well before the end of the last Ice Age (unlike the North American situation), estimates of the duration of coexistence between humans and megafauna remain imprecise. Contrary to recent claims, the existing data do not prove the "blitzkrieg" model of overkill.