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.
Travel from Johannesburg toward the Indian
Ocean some 400 miles to the East, and you start out driving
across flat tableland. Then, around two-thirds of the way
to the sea, you literally drive off the edge of that table.
A scene in the apartheid-era movie The Gods Must Be Crazy
in which a San hunter throws a coke bottle “off the
edge of the world” was filmed there, and that’s
pretty much how the Drakensberg escarpment looks in places.
The interior of South Africa’s “tableland”
is relatively dry, but there’s a narrow band of rain-
and cloud forest along the edge of the “table.”
That forest is characterized by a high level of biodiversity,
and is an important habitat, in particular, of a beautiful
little antelope called the red duiker.
The cloud forest’s biodiversity would be probably be
degraded if the red duiker population grew ten times, or even
twice as large as it is now. Something must, therefore, limit
that population. It’s completely unrealistic to suppose
that red duikers can somehow limit their own population to
a level which is consonant with biodiversity – red duikers
don’t know or care about the balance of nature. Their
population is limited, instead, by a mysterious outside dynamic
which we call “the ecology.”
Somehow, the uncaring efforts of the cloud-forest’s
inhabitants to survive and reproduce are co-ordinated by this
non-existent thing we call “the ecology” in such
a way that no single organism is permitted to monopolize the
resources of the ecosystem of which it’s a member. We
have no idea how “the ecology” achieves that balancing
act. We’re groping our way to understanding it along
a number of avenues – one of which we refer to as “complex
systems theory”– but we’ve made no real
headway as yet.
The “diversity maintaining” limitation imposed
by the ecology on the populations of its member organisms
turns out, moreover, in the very long term, to be a “diversity
producing” limitation: the mere fact that they’re
members of a relatively stable ecosystem seems to “encourage”
organisms to produce opportunities for still more kinds of
organisms to evolve. Those new opportunities are always created
unwittingly, of course, and always as a byproduct of their
creators’ efforts to ensure their own survival and reproduction,
but, over time, they give rise, nonetheless, to the marvelous
and mysterious state of affairs we call “biodiversity.”
The fact that humans have become, in words of the renowned
biologist Edward O. Wilson, “a hundred times more numerous
than any other land animal of comparable size in the history
of life” invites a conclusion which seems both hugely
unlikely and hugely obvious at the same time: our species
has reached a level of efficacy and power at which the ecology
is no longer able to impose the “diversity maintaining”
limitation on us. It’s as if red duikers had gained
the power to eliminate leopards. So many red duikers are killed
by leopards that it would, from the red duiker point of view,
be irresponsible – unthinkable– not to use
that power. Leopards are, however, not the only animals which
limit the lives and aspirations of individual red duikers:
competition from common duikers and blue duikers also keep
red duiker numbers at lower levels than they’d otherwise
reach. From the point of view, therefore, of red duikers who
aren’t getting enough food or finding suitable territories,
it would be obvious, too, that any power which their species
possessed to reduce or eliminate the other duiker species
must also be exercised.
Humans do, of course, have the power to eliminate a wide
variety of organisms which stand between them and the resources
they need and want, and it is as unthinkable for us as it
would be for red duikers – if they had that
kind of power – not to take action against the “problem
animals,” “pests,” and “weeds,”
whose interests conflict with ours. We were, after all, like
red duikers, evolved to care about our own well-being, rather
than about the maintenance of biodiversity.
The mental horizons of humans are, nevertheless, wider than
those of red duikers, and many members of our species are,
in addition to their self-interest, moved by what Darwin characterized,
in the closing sentence of the Descent of Man, as
a “benevolence which extends not only to other men but
to the humblest living creature.” Because of that concern
for other life forms – and because the maintenance of
a certain level of biodiversity is, in the long term, necessary
for our own survival – many of us have begun to give
serious thought to the questions of why our species is causing
a mass-extinction, and whether it can be stopped.
I try to show, in this Part, how this mass extinction began
long before the dawn of written history with our species’
unwitting destruction of the great “Serengetis”
of big mammals, reptiles and birds we spoke about in the Introduction.
CHAPTER 1
– Speak out about
endangered species
