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"New research suggests there was no state of grace: for two million years humankind has been the natural world’s nemesis."
Now even Monbiot, enamored as he is of the preposterous endeavors for "rewilding", is losing the rose-colored glasses about humanity. This is, to my mind, the best article he has ever written - because he deftly eviscerates the revisionists who try so desperately to ignore the obvious extinctions that have followed our species everywhere we migrated...like PigPen's cloud of dirt - even though he presents, at the end, the inevitable rhetorical question: "Can we use our ingenuity, which for two million years has turned so inventively to destruction, to defy our evolutionary history?" the answer to which is, of course, we cannot possibly defy our evolutionary history.
----Gail Zawacki
Destroyer of Worlds
New
research suggests there was no state of grace: for two million years
humankind has been the natural world’s nemesis
George
Monbiot
24
March, 2014
You
want to know who we are? Really? You think you do, but you will
regret it. This article, if you have any love for the world, will
inject you with a venom – a soul-scraping sadness – without an
obvious antidote.
The
Anthropocene, now a popular term among scientists, is the epoch in
which we live: one dominated by human impacts on the living world.
Most date it from the beginning of the industrial revolution. But it
might have begun much earlier, with a killing spree that commenced
two million years ago. What rose onto its hindlegs on the African
savannahs was, from the outset, death: the destroyer of worlds.
Before Homo
erectus,
perhaps our first recognisably-human ancestor, emerged in Africa, the
continent abounded with monsters. There were several species of
elephants. There were sabretooths and false sabretooths, giant
hyaenas and creatures like those released in The Hunger Games:
amphicyonids, or bear dogs, vast predators with an enormous bite.
Amphicyonid
(“bear dog”) skeleton
Professor
Blaire van Valkenburgh has developed a means by which we could
roughly determine how many of these animals there were(1). When there
are few predators and plenty of prey, the predators eat only the best
parts of the carcas. When competition is intense, they eat
everything, including the bones. The more bones a carnivore eats, the
more likely its teeth are to be worn or broken. The breakages in
carnivores’ teeth were massively greater in the pre-human era(2).
Blaire
van Valkenburgh’s tooth breakage graph
Not
only were there more species of predators, including species much
larger than any found on earth today, but they appear to have been
much more abundant – and desperate. We evolved in a terrible,
wonderful world – that was no match for us.
Homo
erectus possessed
several traits that appear to have made it invincible: intelligence,
cooperation; an ability to switch to almost any food when times were
tough; and a throwing arm that allowed it to do something no other
species has ever managed – to fight from a distance. (The
increasing distance from which we fight is both a benchmark and a
determinant of human history). It could have driven giant predators
off their prey and harried monstrous herbivores to exhaustion and
death.
As
the paleontologists Lars Werdelin and Margaret Lewis show, the
disappearance of much of the African megafauna appears to have
coincided with the switch towards meat eating by human ancestors(3).
The great extent and strange pattern of extinction (concentrated
among huge, specialist animals at the top of the food chain) is not
easy to explain by other means.
At
the Oxford megafauna conference last week, I listened as many of the
world’s leading scientists in this field mapped out a new
understanding of the human impact on the planet(4). Almost everywhere
we went, humankind erased a world of wonders, changing the way the
biosphere functions. For example, modern humans arrived in Europe and
Australia at about the same time – between 40 and 50,000 years ago
– with similar consequences. In Europe, where animals had learnt to
fear previous versions of the bipedal ape, the extinctions happened
slowly. Within some 10 or 15,000 years, the continent had lost its
straight-tusked elephants, forest rhinos, hippos, hyaenas and
monstrous scimitar cats.
Straight
tusked elephants once dominated the British ecosystem
In
Australia, where no hominim had set foot before modern humans
arrived, the collapse was almost instant. The rhinoceros-sized
wombat(5), the ten-foot kangaroo, the marsupial lion, the monitor
lizard larger than a Nile crocodile(6), the giant marsupial tapir,
the horned tortoise as big as a car(7) – all went, in ecological
terms, overnight.
Giant
monitor lizard skeleton
A
few months ago, a well-publicised paper claimed that the great beasts
of the Americas – mammoths and mastodons, giant ground sloths,
lions and sabretooths, eight-foot beavers(8), a bird with a 26-foot
wingspan(9) – could not have been exterminated by humans, because
the fossil evidence for their extinction marginally pre-dates the
evidence for human arrival(10).
I
have never seen a paper demolished as elegantly and decisively as
this was at last week’s conference. The archaeologist Todd Surovell
demonstrated that the mismatch is just what you would expect if
humans were responsible(11). Mass destruction is easy to detect in
the fossil record: in one layer bones are everywhere, in the next
they are nowhere. But people living at low densities with basic
technologies leave almost no traces. With the human growth rates and
kill rates you’d expect in the first pulse of settlement (about
14,000 years ago), the great beasts would have lasted only 1,000
years. His work suggests that the most reliable indicator of human
arrival in the fossil record is a wave of large mammal extinctions.
These
species were not just ornaments of the natural world. The new work
presented at the conference suggests that they shaped the rest of the
ecosystem. In Britain during the last interglacial period, elephants,
rhinos and other great beasts maintained a mosaic of habitats: a
mixture of closed canopy forest, open forest, glade and sward(12). In
Australia, the sudden flush of vegetation that followed the loss of
large herbivores caused stacks of leaf litter to build up, which
became the rainforests’ pyre: fires (natural or manmade) soon
transformed these lush places into dry forest and scrub(13).
In
the Amazon and other regions, large herbivores moved nutrients from
rich soils to poor ones, radically altering plant growth(14,15). One
controversial paper suggests that the eradication of the monsters of
the Americas caused such a sharp loss of atmospheric methane
(generated in their guts) that it could have triggered the short ice
age which began 12,800 years ago, called the Younger Dryas(16).
And
still we have not stopped. Poaching has reduced the population of
African forest elephants by 60% since 2000(17). The range of the
Asian elephant – which once lived from Turkey to the coast of China
– has contracted by 97%; the ranges of the Asian rhinos by over
99%(18). Elephants distribute the seeds of hundreds of rainforest
tree species; without them these trees are functionally
extinct(19,20).
Is
this all we are? A diminutive monster that can leave no door closed,
no hiding place intact, that is now doing to the great beasts of the
sea what we did so long ago to the great beasts of the land? Or can
we stop? Can we use our ingenuity, which for two million years has
turned so inventively to destruction, to defy our evolutionary
history?
www.monbiot.com
References:
1.
eg Wendy J. Binder and Blaire Van Valkenburgh, 2010. A comparison of
tooth wear and breakage in Rancho La Brea sabertooth cats and dire
wolves across time. Journal of Vertebrate Paleontology.
http://www.tandfonline.com/doi/abs/10.1080/02724630903413016#.UzBUcM40uQk
2. http://www.eci.ox.ac.uk/news/events/2014/megafauna/valkenburgh.pdf
2. http://www.eci.ox.ac.uk/news/events/2014/megafauna/valkenburgh.pdf
3.
Lars Werdelin, 2013. King of Beasts. Scientific American.
http://www.scientificamerican.com/magazine/sa/2013/11-01/
4.
http://oxfordmegafauna.weebly.com/
5. Diprotodon.
6. Megalania.
8. Castoroides
ohioensis
9.
The Argentine roc (Argentavis
magnificens).
10.
Matthew T. Boulanger and R. Lee Lyman, 2014. Northeastern North
American Pleistocene megafauna chronologically overlapped minimally
with Paleoindians. Quaternary Science Reviews 85, pp35-46.
http://dx.doi.org/10.1016/j.quascirev.2013.11.024
12.
Christopher J. Sandom et al, 2014. High herbivore density associated
with vegetation diversity in interglacial ecosystems. Proceedings of
the National Academy of Sciences, vol. 111, no. 11, pp4162–4167.
www.pnas.org/cgi/doi/10.1073/pnas.1311014111
13.
Susan Rule et al, 23rd March 2012. The Aftermath of Megafaunal
Extinction: Ecosystem Transformation in Pleistocene Australia.
Science Vol. 335, pp 1483-1486. doi: 10.1126/science.1214261.
https://www.sciencemag.org/content/335/6075/1483.full
14.
Christopher E. Doughty, AdamWolf and Yadvinder Malhi, 11 August 2013.
The legacy of the Pleistocene megafauna extinctions on nutrient
availability in Amazonia. Nature Geoscience vol. 6, pp761–764. doi:
10.1038/ngeo1895.
http://www.nature.com/ngeo/journal/v6/n9/full/ngeo1895.html
15.
Adam Wolf, Christopher E. Doughty, Yadvinder Malhi, Lateral Diffusion
of Nutrients by Mammalian Herbivores in Terrestrial Ecosystems. PLOS
One, doi: 10.1371/journal.pone.0071352.
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0071352
16.
Felisa A. Smith, 2010. Methane emissions from extinct megafauna.
Nature Geoscience 3, 374 – 375. doi:10.1038/ngeo877.
http://www.nature.com/ngeo/journal/v3/n6/full/ngeo877.html
17. http://www.salon.com/2014/01/05/african_forest_elephants_are_being_massacred_into_extinction_partner/
"Can we use our ingenuity, which for two million years has turned so inventively to destruction, to defy our evolutionary history?"
ReplyDeleteSilly question that begs no answer. The evidence is "in" - what more does Monbiot need?
If we want to eat - we will kill virtually all life to extinction. It was our "ingenuity" that has continued to make it possible in ever widening methods - and it will be our ingenuity that will ensure we kill everything that is presently left.
Witness the ongoing slaughter of tigers, elephants, bears, rhinoceroses and countless "bush meat". If you still need "proof" then you're not paying any attention.
Ingenuity will not be our salvation as Monbiot hopes, the evidence is "in" on this point too. The species is incapable of stopping. Doesn't 40,000 generations of endless destruction prove that soundly enough?
And what species can "defy (it's own) evolutionary history"? None that I can think of.
So it IS a silly question.
Monbiot should have asked something else altogether: How soon will we go extinct, after having destroyed virtually everything else?
Estimates are "not long now" (a single generation, about 18 years from now). We've triggered quite a few rapidly cascading dominoes of "extinction", which will wind up killing us all (by starvation first, then war, then disease). Our ingenuity will be our undoing in the end. It is not - and never has been - our saving grace.