-Caveat Lector-
Did humans hunt giant mammals to extinction? Or give them lethal
disease
Mammoth Kill
SciAm 2/2001
by Kate Wong
Mexico City--Although it's hard to imagine in this age of urban
sprawl and automobiles, North America once belonged to mammoths,
camels, ground sloths as large as cows, bear-size beavers and
other formidable beasts. Some 11,000 years ago, however, these
large-bodied mammals and others--about 70 species in
all--disappeared. Their demise coincided roughly with the
arrival of humans in the New World and dramatic climatic
change--factors that have inspired several theories about the
die-off. Yet despite decades of scientific investigation, the
exact cause remains a mystery. Now new findings offer support to
one of these controversial hypotheses: that human hunting drove
this megafaunal menagerie to extinction.
The overkill model emerged in the 1960s, when it was put
forth by Paul S. Martin of the University of Arizona. Since
then, critics have charged that no evidence exists to support the
idea that the first Americans hunted to the extent necessary to
cause these extinctions. But at the annual meeting of the
Society of Vertebrate Paleontology in Mexico City last October,
paleoecologist John Alroy of the University of California at
Santa Barbara argued that, in fact, hunting-driven extinction is
not only plausible, it was unavoidable. He has determined, using
a computer simulation, that even a very modest amount of hunting
would have wiped these animals out.
Assuming an initial human population of 100 people that grew
no more than 2 percent annually, Alroy determined that if each
band of, say, 50 people killed 15 to 20 large mammals a year,
humans could have eliminated the animal populations within 1,000
years. Large mammals in particular would have been vulnerable to
the pressure because they have longer gestation periods than
smaller mammals and their young require extended care.
Not everyone agrees with Alroy's assessment. For one, the
results depend in part on population-size estimates for the
extinct animals--figures that are not necessarily reliable. But
a more specific criticism comes from mammalogist Ross D. E.
MacPhee of the American Museum of Natural History in New York
City, who points out that the relevant archaeological record
contains barely a dozen examples of stone points embedded in
mammoth bones (and none, it should be noted, are known from other
megafaunal remains)--hardly what one might expect if hunting
drove these animals to extinction. Furthermore, some of these
species had huge ranges--the giant Jefferson's ground sloth, for
example, lived as far north as the Yukon and as far south as
Mexico--which would have made slaughtering them in numbers
sufficient to cause their extinction rather implausible, he says.
MacPhee agrees that humans most likely brought about these
extinctions (as well as others around the world that coincided
with human arrival), but not directly. Rather he suggests that
people may have introduced hyperlethal disease, perhaps through
their dogs or hitchhiking vermin, which then spread wildly among
the immunologically naive species of the New World. As in the
overkill model, populations of large mammals would have a harder
time recovering. Repeated outbreaks of a hyperdisease could thus
quickly drive them to the point of no return. So far MacPhee
does not have empirical evidence for the hyperdisease hypothesis,
and it won't be easy to come by: hyperlethal disease wold kill
far too quickly to leave its signature on the bones themselves.
But he hopes that analyses of tissue and DNA from the last
mammoths to perish will eventually reveal murderous microbes.
The third explanation for what brought on this North
American extinction does not involve human beings. Instead its
proponents blame the loss on the weather. The Pleistocene epoch
witnessed considerable climatic instability, explains
paleontologist Russell W. Graham of the Denver Museum of Nature
and Science. As a result, certain habitats disappeared, and
species that had once formed communities split apart. For some
animals, this change brought opportunity. For much of the
megafauna, however, the increasingly homogeneous environment left
them with shrinking geographical ranges--a death sentence for
large animals, which need large ranges. Although these creatures
managed to maintain viable populations through most of the
Pleistocene, the final major fluctuation--the so-called Younger
Dryas event--pushed them over the edge, Graham says.
For his part, Alroy is convinced that human hunters
demolished the titans of the Ice Age. The overkill model
explains everything the disease and climate scenarios explain, he
asserts, and makes accurate predictions about which species would
eventually go extinct. "Personally, I'm a vegetarian," he
remarks, "and I find all of this kind of gross--but believable."
=================================================================
Kadosh, Kadosh, Kadosh, YHVH, TZEVAOT
FROM THE DESK OF:
*Michael Spitzer* <[EMAIL PROTECTED]>
~~~~~~~~~~~~~~~
The Best Way To Destroy Enemies Is To Change Them To Friends
=================================================================
o
<A HREF="http://www.ctrl.org/">www.ctrl.org</A>
DECLARATION & DISCLAIMER
==========
CTRL is a discussion & informational exchange list. Proselytizing propagandic
screeds are unwelcomed. Substance—not soap-boxing—please! These are
sordid matters and 'conspiracy theory'—with its many half-truths, mis-
directions and outright frauds—is used politically by different groups with
major and minor effects spread throughout the spectrum of time and thought.
That being said, CTRLgives no endorsement to the validity of posts, and
always suggests to readers; be wary of what you read. CTRL gives no
credence to Holocaust denial and nazi's need not apply.
Let us please be civil and as always, Caveat Lector.
========================================================================
Archives Available at:
http://peach.ease.lsoft.com/archives/ctrl.html
<A HREF="http://peach.ease.lsoft.com/archives/ctrl.html">Archives of
[EMAIL PROTECTED]</A>
http:[EMAIL PROTECTED]/
<A HREF="http:[EMAIL PROTECTED]/">ctrl</A>
========================================================================
To subscribe to Conspiracy Theory Research List[CTRL] send email:
SUBSCRIBE CTRL [to:] [EMAIL PROTECTED]
To UNsubscribe to Conspiracy Theory Research List[CTRL] send email:
SIGNOFF CTRL [to:] [EMAIL PROTECTED]
Om
