permaculture

[Benjamin Horst <benjamin_horst@myrealbox.com>]

Marimike6@cs.com wrote:

> The thesis has been argued for many decades since the 
> 1960's, when this early volume came out, but it is apparent that the world over, major land fauna have disappeared whenever the old paleo hunting culture entered the scene. Thus giant ground sloths, uintatherium, sabertooth cats and horses departed the American scene nine to eleven thousand years ago, when Folsom Man came with his refined toolkit and pack-animal tactics for bringing down big game.
>  
The human-induced megafaunal extinction theory has been in common 
currency for several decades, but in reality there's very little direct 
evidence to support it at this time. In fact, the most recent evidence 
suggests that all the hominids -- from Australopithecus to Homo erectus 
to modern Homo sapiens -- were and are (with the exception of settled, 
urban societies) opportunistic hunters at best. Among almost all modern 
hunter-gatherer groups, hunting does play an extremely significant role 
... but it's largely a symbolic one. Wild game -- most frequently killed 
by men -- has an important religious and social role in most societies, 
but it is the foods often gathered by women, such as plant foods, fungi, 
and shellfish, which provide the lion's share of nutrition, including 
protein, for nearly every hunter-gatherer group (many anthropologists 
are now proposing that we adjust our terminology and refer to these 
groups as gatherer-hunters instead). There's every reason to suppose 
that this general pattern among modern hunter-gatherers or 
gatherer-hunters extends back to our very origins as a species.

The vision of our ancestors as "Man the Hunter" now appears more deeply 
rooted in European and Euro-American fantasies of native and prehistoric 
peoples as uncultured and brutish (and of the impression that male 
activities must somehow be of more importance and value than female) 
than on the anthropological and paleontological record. Technologies 
like the so-called "Folsom toolkit" in North America may have made 
killing mammoths, camels, horses, and giant sloths a little easier, but 
it doesn't necessarily follow that the early Native Americans drove 
these species extinct. The San of southern Africa have been using 
extremely effective stone tools for millenia, but they have yet to drive 
giraffes, elephants, or Cape buffaloes to their demise. In addition, 
North American archeological sites that once seemed to offer conclusive 
evidence of small bands of humans driving thousands of animals over 
cliffs are proving to be less and less human-induced. Humans certainly 
butchered a few of these animals after their deaths, but there is no 
real evidence that they caused the beasts to stampede in the first 
place. As more and more archeology is showing, we've got a far longer 
history of scavenging than we do of hunting, going back all the way to 
our earliest hominid ancestors, the australopiths of the African Rift 
Valley.

So did the Native Americans kill off the mammoth and ground sloth? Did 
the Cro-Magnons finish off the woolly rhino and the cave bear, or the 
Aborigines the giant kangaroo? I'll concede that it's possible. But 
consider that Homo sapiens is a biological organism like any other. 
We're a highly adaptable species, but constrained -- and blessed -- by 
our biological niches like any other species. In the modern, Western 
world we're surrounded by so many technological marvels that we tend to 
forget that we're adapted to any particular niche. However, in the early 
days of Homo sapiens, physical technology was pretty limited, even if 
our art, culture, spirituality, and know-how about our local 
environments were vast.

It seems to me most likely that the spread of humans across the planet 
happened not because of any obvious technology (at least none that's 
been preserved in the archeological record) but because of climate 
shifts and changes in ecosystems. Homo sapiens spread from Africa into 
the Levant, South  and Southeast Asia, and Australia following a climate 
shift at around 50,000 years ago, not after developing a new technology 
(especially not a hunting technology). The expansion into Central Asia 
occurred around 35,000 years ago, at exactly the time climate change 
opened new corridors of grassland into the vast Eurasian steppes, an 
environment somewhat similar to the savannahs our species originally 
evolved in. And movements from Central Asia into Europe and the Americas 
(about 30,000 and 15,000-20,000 years ago, respectively) were also 
accompanied by (caused by?) major changes in climate, including the 
advance and retreat of the glaciers at the end of the last ice age. In 
sum: climate change allowed Homo sapiens to migrate into new areas, so 
might climate change not also have triggered changes in the population 
of other large mammals, including the extinction of many? In any event, 
should we not consider human beings as merely one possible cause of the 
megafaunal extinctions, not the single causal factor? Why, in the 
absence of any definitive data, should we consider humans a more likely 
cause of the North American extinctions than, say, the opportunistic 
grizzly bear, which migrated from Siberia into North America at roughly 
the same time and via the same route? And all this is to say nothing 
about the meteor or comet impact in South America at about 10,000-15,000 
years ago (a smaller version of the Yucatan impact that likely killed 
off the dinosaurs 65 million years ago)  that almost certainly caused 
great clouds of dust over North America -- an event that would have 
caused great stress and hardship for large herbivores and their predators.

In the absence of any real data either way, I believe it is conceivable 
that Homo sapiens killed off megafauna species across the globe. But the 
available evidence, albeit far from definitive, suggests to me that 
climate played a much more significant role. Except for the case of the 
colonization of small, isolated islands such as in Polynesia, it seems 
to me that human-induced mass extinctions have rarely, if ever, occured 
... until recently. It is those of us of European descent who bear the 
responsibility for many megafaunal extinctions -- including the 
Steller's sea cow, the great auk, the tarpan, the quagga, and the 
thylacine, to name just a few. And we bear the greater burden of 
responsibility for the decimation of entire ecosystems and the 
imposition of deserts and monocultures on formerly lush and biodiverse 
regions throughout the world. Our current problem of mass extinctions is 
a cultural one, not one that we (or our ancient predecessors) are 
necessarily biologically predisposed to.

Alas, I'm rather long-winded. So to tie back in to the original thread 
of discussion: yes, "invasive" species, possibly including human beings, 
do occasionally cause extinctions in the areas they "invade," but they 
wouldn't move into these new areas unless some change -- climactic or 
human-induced -- opened up a niche for them to begin with. (Extinctions 
are far more likely in isolated ecologies such as the Pacific and Indian 
Ocean islands where species interchange between geographic areas is 
substantially less frequent than in continental ecologies.) And 
eventually they thrive, and are incorporated as integral members of a 
reorganized local ecosystem, or they die out. The opening up of niches 
is one of the primary mechanisms of speciation, and without it the 
dynamic, creative evolutionary process would grind to an ugly halt.

We opened up a niche, and kudzu moved in to try to fill it. As a result, 
kudzu will eventually be incorporated into the ecosystems of the 
southeastern US, or it will die out. Right now our cultural framework is 
to compete with kudzu for the niche it's trying to fill -- the niche we 
opened up in the first place. It's unclear to me which species is going 
to win the battle for that particular niche, in the end, but for now my 
money's on the kudzu.

Ben Martin Horst