Just to absorb
the fact that these great Serengetis existed…
Mammoths, giant deer, woolly rhinos and many other kinds of
now-extinct big animals lived in Europe until about fourteen
thousand years ago. Human artists created a loving and comprehensive
record of them, exemplified, most memorably, by the famous cave
paintings of France and Spain. Many present-day humans are aware,
for this reason, that “big game” of this kind lived
in Europe. Most are still unaware, though, that similar collections
of “megafauna” lived on all the earth’s
continents except Antarctica around the time those paintings
were being made.
Up to about thirteen thousand years ago the Americas were,
for instance, inhabited by an astonishingly diverse community
of big animals and birds. That community included species
that most people don’t associate with the New World,
like cheetahs, camels and elephants. It’s not enough,
though, to say “the Americas were inhabited by elephants,”
because that statement conveys no idea of how many kinds
of elephants were living on those two continents. Between
them, North and South America were inhabited by no less than
seven elephant or “proboscidean” species.
These proboscideans shared the prairies, pampas, and forests
of the continental New World with more than twenty species
of ground-sloth. The largest of these ground-sloth species
– members of the genera Megatherium and Eremotherium
– approached the size of present-day African elephants.
The biggest of the American elephant species, the Columbian
mammoth, was, however, even larger than these “supergiant”
ground-sloths.
Our detailed knowledge of these lost New World giants (and,
indeed, of all the planet’s recently-vanished megafauna)
stems, as one might expect, mainly from fossilized bones.
The animals in question existed so recently, however, that
their bones barely deserve to be called fossils. They’re
not nearly as mineralized as dinosaur bones, and are augmented,
in many instances, by flesh, skin, hair and feces. “Sub-fossil”
remains of this kind tell us that north Asia was also inhabited
by a “Serengeti” of big animals until about thirteen
thousand years ago. The Siberian Serengeti included the same
mammoth species that inhabited Europe, as well as two grass-eating
rhinoceros species – the “woolly” kind which
extended (like the Eurasian mammoth) into Europe, and the
huge Elasmotherium sibiricum which we’ll take
a closer look at in Chapter 4.
Australia was another big-animal paradise. It was home to
more than a dozen species larger than the 200 lb. red kangaroo
which is presently that subcontinent’s biggest indigenous
mammal. Among them were marsupials roughly equivalent to lions
and rhinoceroses, as well as huge birds and reptiles. This
extraordinary community of marsupial, reptilian and avian
giants started disappearing about forty-five thousand years
ago – somewhat further back in time, then, than its
Eurasian and American counterparts, but still only yesterday
in the evolutionary scheme of things.
Within the last fifty thousand years, therefore, –
the blink of an eye – a world-wide chain of big-animal
communities, comprised of literally hundreds of species, suddenly
vanished from the earth.
* * *
Just to absorb the fact that these great Serengetis existed
– and existed so recently – is already
to wonder what could have happened to them. The Nineteenth
Century paleontologists who first became aware of them, concluded
that they’d been wiped out by another newly-discovered
phenomenon: the Ice Age. As we’ve learned more about
the Ice Age, however, (and about paleontology) it has become
clear to many observers that the diversity of the earth’s
large-animal species was as little affected by the “last
Ice Age,” – i.e. the last glaciation – as
it was by the approximately nine previous glaciations
that have taken place over the last million years. We’ve
had to ask ourselves, therefore, whether some other potentially
destructive process was taking place between ten thousand
and fifty thousand years ago – a disturbance that might,
unlike a glaciation, have been a “one-time” occurrence.
There is, it happens, a strong candidate for that “one-time”
kind of upheaval: the migration out of Africa of Homo
sapiens. Sapiens made its first appearance in
each of the regions from which a “Serengeti” disappeared,
a relatively short time before that disappearance took place.
It had started spilling out of Africa somewhere between 100,000
and 70,000 years ago, reaching Australia perhaps 55,000 years
ago, Europe around 40,000 years ago, Siberia some 30,000 years
ago, and the New World some time after that. Except in the
case of Europe, which was already occupied by H. neanderthalensis,
those new territories hadn’t been occupied by hominids
of any kind prior to the arrival of our species. (Like Europe,
the southern parts of Asia were already inhabited by hominid
emigrants which had left Africa long before sapiens
did.)
The fact that each of the vanished Serengetis disappeared
relatively soon after our species settled in the area in which
it lived, raises, in itself, a strong suspicion that Homo
sapiens was responsible for those disappearances. For
some observers of this phenomenon, that suspicion has hardened
into certainty. As far back as 1987, the late Isaac Asimov
had already, in his Beginnings book, dismissed this
issue as “a silly thing to argue over”:
Of course human beings were responsible.
Even if human beings didn’t actively hunt the animals
to death, which I bet they did, they gradually took up the
living space. Large animals are particularly vulnerable
under such conditions. They require a great deal of food
and, therefore, a great deal of space within which to find
their food. They are relatively few in number, at best.
They grow slowly, and have few young and those at comparatively
long intervals.
Speaking specifically about the destruction of the North American
Serengeti, John Alroy, a research biologist with the National
Center for Ecological Analysis and Synthesis at Santa Barbara,
expressed the same conclusion in more academic but equally emphatic
language in 1999:
My own position is that the overkill [of
the North American megafauna by humans]...has been “proven”
as thoroughly as any historic hypothesis can be. All of
the key evidence was available years ago, and all of it
firmly refutes competing, ecologically-oriented hypotheses.
The event’s timing, rapidity, selectivity and geographic
pattern all make good sense according to the anthropogenic
model, and no sense at all otherwise. To my eyes, this assessment
is so clear that further “tests” are not really
necessary.
If the “humans did it” explanation has been proved,
however, as conclusively as these two observers think it has,
then why aren’t people talking about of it?
Why are so few members of the conservation or environmental
movements aware of the vanished Serengetis? And why,
finally, do some of the people who do know about
them – specialists, in many cases, like paleontologists
and museum curators – still cling to the intellectually
untenable belief that they were destroyed by climate change
associated with “the Ice Age”?
* * *
The reason why the story of the vanished Serengetis and their
destruction by humans hasn’t found its way into the
general consciousness, is that it contradicts just about everything
we think we know about our species. To many of us it’s
still “obvious” that the first humans to settle
the Americas and Australia – the “native”
or “aboriginal” inhabitants of those continents
– lived in harmony with the natural world. It’s
widely assumed, in fact, that no members of Homo
sapiens wiped out other species before the industrial
revolution. Just to conceive of the possibility that our species
might have destroyed the vanished Serengetis would, therefore,
require an entirely different conception of human ecological
history.
That new history would start with the currently unfashionable
fact that members of the human family had already learned
to hunt animals larger than themselves as far back as the
Late Pliocene. It would go on to tell us that, during the
early Pleistocene, some 1.4 million years ago, the technological
capabilities of one hominid species – Homo erectus
– had already became formidable enough to cause the
extinction of several big-animal species in Africa and South
Asia. It would describe how the growth of those technological
capabilities would accelerate toward the end of the Pleistocene,
enabling our species, Homo sapiens, to enter Australia,
Northern Eurasia, and the New World, where it would encounter,
and exterminate, a great many big animal, reptile and bird
species which had not – in contrast with the big animals
of Africa and South Asia – had the opportunity to develop
a measure of resistance against the growing ingenuity of the
hominid family.
This new history of our species would inform us, further,
that an unbroken flow of human-caused extinctions was to continue
after the end-Pleistocene destruction of the Australian,
European, North Asian and American Serengetis, and that this
flow would swell, in the last century or two, into the enormous
mass-extermination which our species is presently inflicting
on the biosphere.
It would suggest, finally, that the phenomenon of human-caused
mass-extinction was not set in motion by cruelty, greed or
thoughtlessness on the part of our species. The first humans
to arrive in Australia didn’t want to wipe
out the marsupial “rhinos” and “lions”
they met up with on that island continent, nor did they even
know that they were doing it. To a large extent, present-day
humans still lack the consciousness needed to control their
impact on the natural world, and it’s by no means impossible
that the destructive impact of our species will turn out to
be an unstoppable and inevitable process – the price
that is paid, for all we know, in every biosphere where a
level of intelligence equal to ours develops.
If humans do, however, develop the ability to control
their impact on the biosphere while there’s still something
worthwhile to save, they will do so through the acquisition
of knowledge and awareness. Ecological salvation appears to
depend, therefore, on the same phenomenon that initiated the
current mass-extinction: the power of the human intellect.
Before it can work effectively, however, toward stopping the
extinction-spasm which it’s causing, that intellect
will have to free itself of the myths which currently becloud
its understanding of the biodiversity crisis, and acquaint
itself with the real ecological history of its possessors.
PART 1
Humans and their hominid ancestors have been exterminating big-animal
species for a much longer period of time than we could, until
recently, have imagined.
