Megafaunal extinction: climate, humans and assumptions

Recently in TREE, Burney and Flannery reviewed the role of colonizing humans in prehistoric extinctions. Their treatment is informative and we applaud the broad assertion that realistic explanations will not be found in simple, single-cause paradigms. However, despite some qualification, the authors strive to present human influences as primary in all instances: '…a more interesting extinction debate lies within the realm of potential human-caused explanations and how climate might exacerbate human impacts'. We question an underlying assumption that evidence from remote islands can be extrapolated to continents, and challenge suppositions underpinning human causation for extinctions in Australia and the Americas, where most megafaunal losses occurred.