savanna = human refugium

PNAS 102:6231-6
Global archaeological evidence for proboscidean overkill
Todd Surovell, Nicole Waguespack & P Jeffrey Brantingham 2005

One million years ago, proboscideans occupied most of Africa, Europe, Asia,
and the Americas. Today, wild elephants are only found in portions of
sub-Saharan Africa and South Asia. Although the causes of global Pleistocene
extinctions in the order Proboscidea remain unresolved, the most common
explanations involve climatic change and/or human hunting. In this report,
we test the overkill and climate-change hypotheses by using global
archaeological spatiotemporal patterning in proboscidean kill/scavenge
sites. Spanning 1.8 million years, the archaeological record of human
subsistence exploitation of proboscideans is preferentially located on the
edges of the human geographic range. This finding is commensurate with
global overkill, suggesting that prehistoric human range expansion resulted
in localized extinction events. In the present and the past, proboscideans
have survived in refugia that are largely inaccessible to human populations.

In the present and past, elephants have survived in refugia unreached by
humans or those where humans did not exist at sufficient population
densities to cause local extinction. ...


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