[...] creatures and plants live together in a combination of competition and mutual dependency, and it is that combination that is the important thing to consider.

Every species has a primary Malthusian capacity. Any species that does not, potentially, produce more young than the number of the population of the parental generation is out. They’re doomed. It is absolutely necessary for every species and for every such system that its components have a potential positive gain in the population curve.

But, if every species has potential gain, it is then quite a trick to achieve equilibrium. All sorts of interactive balances and dependencies come into play, and it is these processes that have the sort of circuit structure that I have mentioned.

The Malthusian curve is exponential. It is the curve of population growth and it is not inappropriate to call this the population explosion.

You may regret that organisms have this explosive characteristic, but you may as well settle for it. The creatures that don’t are out.

[Gregory Bateson]
'Conscious Purpose versus Nature', Steps to an Ecology of Mind, p.436

Given a source of variation and a selection procedure, systems always evolve in a manner that is easy to describe in general and impossible to predict in detail. The overview is that they take up every opportunity available to them: that’s the part that’s easy to describe.

What’s impossible to predict is how and in what order they’ll do it. That’s true of cellular automata, and it’s also true of living things over time. Follow the evolutionary trajectory of any group of living things, from club moss to crocodiles to Galapagos finches to human beings, and you’ll see that same process at work.

Metaphorically, it’s as though you were inflating a big balloon inside a space too small to contain it: the balloon pushes outwards in all directions, now here, now there, until it runs up against the hard limits of walls and floor and ceiling.

Do evolutionary breakthroughs take place? Of course, and the process just outlined explains how and why those happen. Imagine for a moment that you’ve got a balloon made of some absurdly flexible substance, so that it can just keep stretching no matter how big it gets. You start inflating it inside your bedroom.  The door’s closed, the windows are closed, pretty soon the balloon’s outer surface is pushing hard against the walls, the floor, the ceiling, and the furniture—but there’s an inch-wide gap under the door you forgot about. Once the pressure gets high enough, the balloon pushes out through that gap, and all of a sudden it’s in the hallway and there’s a vast amount of previously inaccessible space for it to expand into.

Whoosh! Before long it’s filling up the living room and pushing against half a dozen other doors and windows. If one of those happens to be open a little, another evolutionary breakthrough follows. It’s not a linear process, and many different lines of evolutionary development can—and did—unfold at the same time.

That’s the story of life on Earth. The walls, floor, and ceiling are the laws of nature and the limits of environment, and the balloon represents the range of niches occupied by living things.

[John Michael Greer]
‘Against Enchantment I: Ken Wilber’, Ecosophia

For the first long, long period, human population growth was held in check by negative feedback because we were part of ecosystems. And disease, famines, resource shortages, those sorts of things kept human populations in check, just like every other species.

Humans are no different from other species in our population dynamics. We have a natural propensity to expand exponentially, but we're held in check by the natural negative feedbacks of the human ecosystem.

Along comes fossil fuel, particularly in the early part of the 19th century when we began to use it in great quantity, as well as an advance of public health measures. Fossil fuel provided the means by which humans could acquire all the food and other resources needed to grow the human enterprise, and public health improvements increased the longevity and health of the population.

So for the first time in human history in the last, about one tenth of 1% of human history, humans were able to realize our full potential for exponential population growth. Until then, it had been suppressed […] We have found ways to relieve the negative feedback, allowing the positive feedback to take off.

We took the cork off the bottle and we've had this enormous population and boom of the whole human enterprise in just the past 200 years. So what we take to be the norm […] is the single most abnormal period in human history. We are like any other species exposed to an abundance of resources that goes through a population boom - there will be a bust, there has to be a bust because the boom can't continue.

Any system that is primarily driven by positive feedback is self-destructive because it means that it will grow forever in a situation, in a context which is clearly not going to grow forever. And we're no different […] I'll put it bluntly, we are in the plague phase of a one-off human population boom bust cycle. We're nearing the top and we will come down because of the onset of negative feedback. Nature will restore balance between that positive and negative feedback and who knows what will come of that.

[William Rees]
‘William E. Rees: "The Fundamental Issue - Overshoot" | The Great Simplification #53’, Nate Hagens, YouTube

[…] K-selected species tend to always to press up against the available carrying capacity of their environments […] using whatever resources are available […] Our evolutionary success depends on high survival rates of infants and this constant pushing up against that carrying capacity.

By the way, that was Malthus's great insight. He realized that if more food was made available, human beings being K strategists would in effect always rise to the level of food availability.

[William Rees]
‘William E. Rees: "The Fundamental Issue - Overshoot" | The Great Simplification #53’, Nate Hagens, YouTube

[…] there's no inherent conflict between technology and ecological thinking. The conflict comes from assuming you can use the technology to overcome the biophysical reality within which we are embedded.

So if we decided as a species 200 years ago, that the carrying capacity of planet Earth indefinitely was say 2 billion people, we could have used technology at an appropriate scale to ensure the continued wellbeing of some 2 billion people ad infinitum.

But we didn't do that. The assumption was that technology can increase carrying capacity indefinitely […]

[William Rees]
‘William E. Rees: "The Fundamental Issue - Overshoot" | The Great Simplification #53’, Nate Hagens, YouTube

In many cases the relationships, the stable relationships that indigenous peoples have developed with their natural environments occur after they've obliterated the natural environment. They occur after they've hunted out all of the megafauna, the large easily caught species.

If you just think of New Zealand, which has been settled since 800 years ago or so, 12 species of gigantic birds went extinct as a result of the deprivations of the indigenous people that now occupy New Zealand. The decimation of populations of large mammals […] in Australia just follows the progression of the occupation of that subcontinent by aboriginals in the last 50,000 years.

So yes, we can develop a harmonious relationship with our ecosystems, but often only after we've inserted ourselves into those ecosystems and appropriated the habitats and food chains of many of the mammals […]

[William Rees]
‘William E. Rees: "The Fundamental Issue - Overshoot" | The Great Simplification #53’, Nate Hagens, YouTube

Any species capable of exponential growth will respond to a period of resource abundance. And many species in nature go through cycles. It's a boom bust cycle: things get good, we expand, then negative feedback kicks in, we crash, then we get good and expand.

Humans have never done that, not globally. We've done it locally.

But now for the first time we've managed to, in effect, colonize the entire planet. We've grown by liquidating our capital [but] you cannot continue to grow by liquidating the natural capital basis of your own existence. And so we get to the point where we become so large, there's simply insufficiency there to maintain even the maintenance activities, let alone further growth.

[William Rees]
‘William E. Rees: "The Fundamental Issue - Overshoot" | The Great Simplification #53’, Nate Hagens, YouTube

We can't avoid the reality that humans are biophysical entities, that we are ecological species that have evolved as components of nature and that we require a certain energy flow just to breathe.

Historically, that energy flow has always been solar energy through our food supply. We broke from that, oh, just about 200 years ago. And with this exosomatic or outside the body source of energy called fossil fuel, we vastly increased our capacity to exploit and destroy the planet.

And so we see everywhere measurements of the decline in forest fertility. North America has lost 50% to 70% of the organic nutrients that took 11,000 or 12,000 years in the Postglacial period to accumulate. So in less than 200 years of deep tillage agriculture, half of that's gone or 70% is gone. And the only way we maintain the productivity of the Great Plains is through the massive applications of fertilizers and pesticides and increasing irrigation.

[William Rees]
‘William E. Rees: "The Fundamental Issue - Overshoot" | The Great Simplification #53’, Nate Hagens, YouTube

William Rees: The biophysical reality is that human beings in the growth of the human system have displaced other species from their eco-niches. It's a concept I call competitive displacement.

Human unsustainability is a natural phenomenon. We are unsustainable by nature because all we're doing is following our natural propensity to expand and to fill all available habitat, but we do it better than any other species.

So if you go back 10,000 years, humans were fewer than, or less than 1% of the biomass of mammals on planet Earth. Then with agriculture and just more recently in the last couple of 100 years with fossil energy and the massive expansion of the human enterprise, humans have become 36% or 34% of the biomass of mammals.

And by the way, the biomass itself has gone up. But our domestic animals are another 62-63%. So that when you add all of that together, it means that wild mammals on planet Earth today are about 3%-4% of the total biomass of mammals. So all those great herds you see in Africa are a trivial appendage on the biomass of mammals, which has absolutely been commandeered by both humans and our domestic animals.

So there's been an enormous displacement of non-human species, and the remaining populations in the last 50 years have been reduced by 65-70%.

Nate Hagens: It's actually worse than that because it’s all mammals, including ocean mammals. So if it's only land mammals, it's 98%.

[William Rees & Nate Hagens]
‘William E. Rees: "The Fundamental Issue - Overshoot" | The Great Simplification #53’, Nate Hagens, YouTube

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