Dear HCN,
Thanks
for the 13 May issue, with the discussion of how past changes in
North American ecosystems affect decisions we now face in the West.
You might say that those who forget prehistory are doomed to repeat
it.
The letters from Linda Driskill (HCN,
6/24/02:Review gives only one view) and Kali Kaliche (HCN,
7/8/02:HCN offers bogus theories) might lead readers to mistakenly
assume that the arrival of humans in North America was unrelated to
the extinction of many large animals, and that this is a misguided,
anti-Indian polemic. The association has been strongly reinforced
in the past few years in the journal Science: Humans arrived in
Australia just prior to the megafauna extinction there about 50,000
years ago; Eurasia, where humans were well-established, didn’t see
remotely the same level of extinctions as North (and South) America
at the close of the Pleistocene; and the climate is an unlikely
culprit, because climactic variations comparable to or greater than
those 10,000 years ago occurred many times in the past couple
million years without producing an extinction event remotely
comparable to that at the end of the
Pleistocene.
What remains highly controversial is
how humans caused such events. For instance, in Australia, some
workers think that introduction of man-made fire was critical. In
North America, it has been suggested that humans carried a
superdisease. But a computer simulation that, while hardly
conclusive, does suggest rapid extinction can be driven by the kind
of hunting likely to have occurred 10,000 years
ago.
Humans have twice decapitated North American
ecosystems: once 10,000 years ago directly or indirectly, and now
again by either hunting and trapping predators (in most places) or
(ironically) by removing human hunting from within national parks.
When we seek to manage these ecosystems, we have
to ask what ecosystem we are trying to create:
1491 ecosystems, in which case we must reproduce the native hunting and land management that shaped these systems, or
one representing what a human-free North America would have looked like, in which case we must simulate saber-toothed tigers, dire wolves, mastodons and the like, or
a new ecosystem working forward from
the remnants of Pleistocene life but without human
involvement?
By default we have been doing the
third, but until this question is answered, land managers
throughout the West will be making piecemeal decisions without a
real goal.
Craig H. Jones Associate Professor of
Geology University of Colorado at
Boulder
This article appeared in the print edition of the magazine with the headline Forward from the Pleistocene.
Republish our articles for free, online or in print, under a Creative Commons license.
