For the first billion years of life on Earth, all of our
ancestors were single celled. One day, we
aren’t sure why, a hungry organism ate a delicious bystander, and became the
first predator. Predation inspired
evolution to become very creative. Some
organisms became mobile by developing cilia or tails. Others shape shifted into multi-celled life
forms. Critters developed scales,
spikes, shells, fangs, and many other clever defenses. Thus, one group survived by dining on the
unlucky, and the bigger group survived by evolving every imaginable trick for
cancelling lunch dates with predators.
When predators became too powerful, they would wipe out their
food supply, blush with embarrassment, and starve. Prey that managed to survive evolved stronger
defensive capabilities. But if they got
too good at this, their population would explode, deplete the available nutrients,
and the vast mob would perish in an undignified manner.
Thus, evolution is an elegant balancing act. If the prey gets one percent faster, the
predator gets one percent faster, not two.
This balancing act is the subject of William Stolzenburg’s book, Where the Wild Things Were. More specifically, the book focuses on how
humankind uses its brilliant technological innovations to bypass the limits of
our current state of evolution, upset healthy balancing acts, and devastate
ecosystems, often unintentionally.
In the early 1970s, zoologist James Estes travelled to the
Aleutian Islands of Alaska to do research on sea otters. Sea otters can grow up to four feet long (1.2
m), and they have incredibly soft fur.
Stylish women with too much money loved wearing fur coats, and for 150
years, from Alaska to Baja, otter hunting was a serious business, and very
profitable. Somewhere between 500,000
and 900,000 otters lost their hides to the fashionable dames of high society.
The island of Amchitka had a healthy population of otters,
and this is where Estes began his study, scuba diving in frigid water. Beneath the waves were thriving jungles of
kelp, a popular hangout for a number of aquatic herbivores. Kelp can grow up to 200 feet tall (61
m). Urchins enjoy dining on kelp, and
sea otters enjoy dining on urchins. What
Estes observed was a healthy balance between the kelp, urchins, and otters.
Later, he spent some time on the island of Shemya, where the great
extermination had wiped out the otters.
Only a few had since recolonized there.
The ecosystem here was stunningly different from Amchitka. In the absence of otters, the urchins
exploded in numbers, and many were huge in size. The sea floor was wall-to-wall urchins, and there
was no kelp at all.
So, when the keystone predators (otters) live in peace, the
ecosystem is healthy and balanced. When
they are eliminated, the ecosystem becomes a train wreck — a chain reaction
known as a trophic
cascade. Predators are
essential.
A similar scenario occurred when Zion National Park was
established in Utah. To make the park
safe for tourists, the cougars (mountain lions) were exterminated. In their absence, the population of mule deer
exploded, and the land was stripped of vegetation. The forests were dying, because young
seedlings were devoured by deer.
Meanwhile, over the hill in North Creek Canyon, the cougars had been
left alone, and the land was remarkably alive and healthy.
The Kaibab Plateau in Arizona became a game preserve in
1906. Deer hunters were kept out, and
6,000 large carnivores were deleted. The
deer population skyrocketed from 4,000 to 100,000, and the vegetation was promptly
vacuumed up. In the winters of 1924 and
1925, 80,000 deer starved to death. Ecosystems
pay an enormous price for the stunning ecological ignorance of literate,
educated people, who spend years in miserable classrooms carefully absorbing spooky
illusions.
Wolves and grizzlies had been absent in the Tetons for quite
a while. Then, a few began drifting in
from Yellowstone. At first, the moose
and elk had no fear of them. Wolves
calmly strolled into the herd and snatched their young. Before long, they learned that fearing
predators was beneficial. Something
similar to this innocent fearlessness likely existed in every ecosystem when
humans first arrived with their state-of-the-art killing technology.
In the 1950s, Paul Martin connected some archaeological
dots. The megafauna of the world, that
had survived almost two million years of ice ages, suddenly blinked out
whenever armed humans arrived in a new region.*
This realization gave birth to his Pleistocene Overkill hypothesis,
“that man, and man alone, was responsible for the unique wave of Late
Pleistocene extinction.” Despite many
loud objections, it has generally been accepted, but it fails to explain the
large numbers of mammoths and rhinos found in Siberia and Alaska. It also causes those who worship at the
crumbling Temple of Human Omnipotence to become moody and irritable.
Whatever your opinion on this controversy, it’s easy to argue
that during the long era of warm weather (since 9600 B.C.), the pristine state
of America was the Pleistocene, not 1492.
In 2005, a group of biologists published a paper on rewilding in the
journal Nature. It recommended the reintroduction of missing
species like cheetahs, camels, lions, and elephants. The mainstream crowd soiled their britches
and howled hysterically.
It was, like, totally groovy to reintroduce pretty
butterflies, but the huge backlash boiled down to “no lions in my backyard!” This was the lively kickoff for what will be a
long and bumpy process of attitude evolution — or a fierce backlash from those
who have yet to free themselves from the tiny cage of anthropocentric hallucinations.
I wonder if the systematic extermination of millions of
predators over the years is associated in any way with the current explosion in
the human population. When climate
change forced our ancestors onto the savannah, evolution had not prepared us
for living amidst fast, powerful, heavyweight predators. We developed a highly unusual dependence on
technology in order to survive, thereby knocking over the evolutionary
balancing act. “They would eventually
wield the power to level mountains, to dam the biggest rivers, to coat entire
continents in concrete and crops, to alter the climate as it had once altered
them.” The chapter on how we morphed
into apex predators is fascinating.
Today, we almost never encounter man-eating predators running
lose. We no longer have to pay careful
attention to reality, ready to react at any moment, fully present and alive. The world has become safe for pudgy cell
phone zombies — an empty, dull, and lonely place. This is seen as normal. I disagree.
* Megafauna survived in Africa because they evolved together
with hominids, but there’s more to the story.
Lars Werdelin, a specialist in African carnivores, has learned that
there used to be far more large carnivores.
Between 2 and 1.5 million years ago, many large carnivores went extinct. This is about the time that tool-using,
meat-eating Homo
erectus appeared. (Werdelin,
Lars, “King of Beasts,” Scientific
American, November 2013, pp. 34-39.)
Stolzenburg, William, Where
the Wild Things Were, Bloomsbury, New York, 2008.
No comments:
Post a Comment