How to Live on a Planet

27 September 2017


Humanity is learning, slowly, how to live on a planet. What does it mean to live on a planet? Why is this significant? How has our way of living on a planet changed over time? How exactly does an intelligent species capable of niche-construction on a planetary scale go about revising its approach to niche construction to make this process consistent with the natural history and biospheric evolution of its homeworld?

Once upon a time the Earth was unlimited and inexhaustible for human beings for all practical purposes. Obviously, Earth was was not actually unlimited and inexhaustible, but for a few tens of thousands or hundreds of thousands of hunter-gatherers distributed across the planet in small bands, this was an ecosystem that they could not have exhausted even if they had sought to do so. Human influence over the planet at this time was imperceptible; our ancestors were simply one species among many species in the terrestrial biosphere. Even before civilization this began to change, as our ancestors have been implicated in the extinction of ice age megafauna. The evidence for this is still debated, but human populations had become sufficiently large and sufficiently organized by the upper Paleolithic that their hunting could plausibly have driven anthropogenic extinctions.

In this earliest (and longest) period of human history, we did not know that we lived on a planet. We did not know what a planet was, the relation of a planet to a star, and the place of stars in the galaxy. The Earth for us at this time was not a planet, but a world, and the world was effectively endless. Only with the advent of civilization and written language were we able to accumulate knowledge trans-generationally, slowly working out that we lived on a planet orbiting a star. This process required several thousand years, and for most of these thousands of years the size of our homeworld was so great that human efforts seemed to not even make a dent in the biosphere. It seemed the the forests could not be exhausted of trees or the oceans exhausted of fish. But all that has changed.

In the past few hundred years, the scope and scale of human activity, together with the size of the human population, has grown until we have found ourselves at the limits of Earth’s resources. We actively manage and limit the use of resources, because if we did not, the seven billion and growing human population would strip the planet clean and leave nothing. This process had already started in the Middle Ages, when many economies were forced to manage strategic resources like timber for shipbuilding, but the process has come to maturity in our time, as we are able to describe and explain scientifically the impact of the human population on our homeworld. We have, today, the conceptual framework necessary to understand that we live on a planet, so that we understand the limitations on our use of resources theoretically as well as practically. When earlier human activities resulted in localized extinctions and shortages, we could not put this in the context of the big picture; now we can.

Today we know what a planet is; we know what we are; we know the limitations dictated by a planet for the organisms constituting its ecosystems. This knowledge changes our relationship to our homeworld. Many definitions have been given for the Anthropocene. One way in which we could define the anthropocene in this context is that it is that period in terrestrial history when human beings learn to live on Earth as a planet. Generalized beyond this anthropocentric formulation, this becomes the period in the history of a life-bearing planet in which the dominant intelligent species (if there is one) learns to live on its planet as a planet.

In several posts I have written about the transition of the terrestrial energy grid from fossil fuels to renewable resources (cf. The Human Future in Space, The Conversion of the Terrestrial Power Grid, and Planetary Constraints 9). This process has already started, and it can be expected to play out over a period of time at least equal to the period of time we have been exploiting fossil fuels.

I recently happened upon the article How to Run the Economy on the Weather by Kris De Decker, which discusses in detail how economies and technologies prior to the industrial revolution were adapted to the intermittency of wind and water, and the adaptability of such habits to contemporary technologies. And I recall some years ago when I was in Greece, specially the island of Rhodes, every house had solar water heaters on the roof (and, of course, sunshine is plentiful in Greece), and everyone seemed to accept as a matter of course that you must shower while the sun is out. A combination of very basic behavioral changes supplemented by contemporary technology could facilitate the transition of the terrestrial power grid with little or no decline in standards of living. This is part of what it means to learn to live on a planet.

As we come to better understand biology, astrobiology, ecology, geology, and cosmology, and we thus come to better understand our homeworld and ourselves, we will learn more about how to live on a planet. But the expansion of our knowledge of exoplanets and astrobiology will be predicated upon our ability to travel to other worlds in order to study them, and if we are fortunate enough to endure for such a time and to achieve such things, then we will have to learn how to live in a universe.

The visible universe is finite. Though the visible universe may be part of an infinitistic cosmology (or even an infinitistic multiverse), the expansion of the universe has created a cosmological horizon beyond which we cannot see. I have previously quoted a passage from Leonard Susskind to this effect:

“In every direction that we look, galaxies are passing the point at which they are moving away from us faster than light can travel. Each of us is surrounded by a cosmic horizon — a sphere where things are receding with the speed of light — and no signal can reach us from beyond that horizon. When a star passes the point of no return, it is gone forever. Far out, at about fifteen billion light years, our cosmic horizon is swallowing galaxies, stars, and probably even life. It is as if we all live in our own private inside-out black hole.”

Leonard Susskind, The Black Hole War: My Battle with Stephen Hawking to make the World Safe for Quantum Mechanics, New York, Boston, and London: Little, Brown and Company, 2008, pp. 437-438

We know, then, scientifically, that the universe is effectively finite as our homeworld is finite, but the universe is so large in comparison to the scale of human activity, indeed, so large even in comparison to the aspirational scale of human activity, that the universe is endless for all practical purposes. Though we are already learning how to live on a planet, in relation to the universe at large we are like our hunter-gather ancestors dwarfed by a world that was, for them, effectively endless.

Only at the greatest reach of the scale of supercivilizations will we — if we last that long and achieve that scale of development — run into the limits of our home galaxy, and then into the limits of the universe, at which time we will have to learn how to live in a universe. I implied as much in an illustration that I created for my Centauri Dreams post, Stagnant Supercivilizations and Interstellar Travel (reproduced below), in which I showed a schematic representation of the carrying capacity of the universe. At this scale of activity we would be engaging in cosmological niche construction in order to make a home for ourselves in the universe, as we are now engaging in planetary-scale niche construction as we learn how to live on a planet.

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