Earth in Human Hands

by David Grinspoon

  DNA analyses of modern people suggest that the human population declined dramatically, to perhaps only a few hundred. When we talk about all men and women being brothers and sisters, and people of all types being closely related, we are not just being poetic and romantic. Compared to other species, humans exhibit very little genetic diversity, a trait that stems back to that time, not too long ago, when a small band of survivors had to repopulate humanity.

  We don’t know exactly when this “genetic bottleneck” happened, or where in Africa the survivors lived and hung on. They may all have lived in one small region of the southern African coast. Curtis Marean, a paleoanthropologist at the Institute of Human Origins at Arizona State University, has for many years been leading a team excavating an area called Pinnacle Point, near the southern tip of present-day South Africa, and has come to believe that this is the site where modern humans emerged. When most of Africa had become uninhabitable due to climate change, the people at Pinnacle Point survived largely on shellfish and coastal vegetation. They had to adopt a new lifestyle, and they developed sophisticated new technologies, including heat treatment of rocks in specially made and controlled fires to make spear points for hunting. This is an example of a “long-chain complex recipe technology,” something that requires a sequence of steps to be performed in just the right way in order to produce the desired product. It’s the kind of process that makes you say, “How the hell did they figure that out?” because there is no obvious connection between the starting materials, the details of the process, and the finished product. Such methods would have required language to pass detailed knowledge between generations. The people of Pinnacle Point also apparently made art and pigments for symbolic self-adornment. So they had language and arts, and were creators and teachers of a sophisticated material culture. They may not have been the first modern humans, but they seem to have been among the earliest.

  We were once an endangered species almost completely wiped out by climate change. Some would say that we are again today (although this confuses the plausible threat of societal decline and collapse with the much more unlikely threat of human extinction). Back then, we avoided extinction by utilizing and honing our unique skills at cooperation, group innovation, and technological cleverness.

  Now, strangely, we’ve been so successful at those skills that we’ve accidentally triggered a new era of climate change that again challenges us to evolve. We may be near the beginning or the end of the story of present-day human civilization—or both. We may be nearing the end of a ten-thousand-year adventure and beginning a much longer one.

  Welcome to the Sapiezoic Eon

  Some see the concept of an Anthropocene epoch as grandiose. They wonder if the coming of humanity is really so important, seen against the immense backdrop of Earth history. They worry that we are thinking too big. Yet I think the opposite is true. Maybe in thinking of it as only a new epoch we are thinking way too small. A shift to a new epoch is not that rare. An epoch typically lasts for a few million years, which, for Earth, means it’s no big deal. Yet this is not merely another geological shift among many in Earth’s long, ever-changing history. The advent of conscious agency as a force of change on Earth is a major inflection point in the way the planet functions. What we are witnessing, and manifesting, is something much more significant than a shift to just another epoch. It is more properly regarded as the potential dawning of a new eon.

  Just as we divide our days into hours, minutes, and seconds, we divide geological time into different-size units. Look again at the diagram of the geological timescale shown here of the photo insert. The column on the right shows the epochs, typically lasting a few million years. These form convenient markers for scientists studying the detailed and tangled history of different locations around Earth. They generally don’t represent major directional Earth changes so much as fluctuations in the complex interplay between changing geography, oscillating climate, and evolving species.

  As you go left on the chart, you come to larger and larger segments of time: periods, which last for several tens of millions of years; and then eras which are much longer, each encompassing several periods. Finally, at the very left of the chart, we have the largest time divisions, the eons. There have been only four eons. Each represents a completely different phase of planetary history. During each, Earth was a fundamentally different planet. The transitions between them were revolutions in the relationship between life and the planet.

  Let me summarize briefly the four eons of Earth history. Here I will gloss over a lot of detail in favor of some essentials. In very crude terms, to which any trained geologist will howl with a million caveats and complexifications, the four eons of Earth, and the transitions between them can be described as follows:22

  The Hadean Eon, roughly the first half-billion years, was so named because it was pure hell, or would have been if anyone had been around to experience it. My friend and former officemate Kevin Zahnle, one of the galaxy’s top experts on planetary origins and evolution, has referred to the Hadean as “a world of exuberant volcanism, exploding meteors, huge craters, infernal heat, and billowing sulfurous steams; that is, a world of fire and brimstone punctuated with blows to the head.”23

  The Archean Eon is often said to have begun 3.8 billion years ago with the origin of life. Some have attached it to the appearance of the first rock. Either definition would mean that the date will keep moving earlier in time as we explore Earth’s past more fully, or, as Zahnle states it, this “puts the Hadean into the same category as the fastest mile or the tallest building.” Sometimes its start date is simply pegged at 4 billion years ago.

  The Proterozoic Eon began 2.5 billion years ago, at the time when oxygen from photosynthesis began building up in the atmosphere, generating the Great Oxygenation Event that I write about in chapter 3. This is arguably when life took over Earth’s atmosphere, and so may also have been the origin of Gaia, or the time when life became a global entity.

  The Phanerozoic Eon began 542 million years ago, with the Cambrian explosion. This was when life suddenly became complex and macroscopic. Up to that time, life had consisted almost entirely of single-celled organisms. Suddenly Earth became a world crawling with animals and plants.

  So, to simplify further, and summarize each with a one-liner:

  Hadean: origin of Earth

  Archean: origin of life

  Proterozoic: Great Oxygenation Event, origin of global biosphere

  Phanerozoic: origin of complex life

  When trying to put our planet and ourselves in the context of cosmic evolution, and asking what parts of the Earth story might possibly be universal, it’s best to ignore the epochs and periods on the right side of the geologic timescale. Our eyes are drawn toward the major eon transitions shown on the left side of the diagram. [See here of the photo insert.]

  It seems obvious to all but the writers of grade B science-fiction films and some of the more gullible UFO conspiracists that the evolution of life, however it may have unfolded elsewhere in the universe, will not, in the details, resemble what has occurred on Earth. Consider a roughly Earth-size exoplanet around a Sun-like star thirty light-years away. You can bet there will not be any Jurassic there—no dinosaurs. There will not be a Pleistocene. No woolly mammoths. The epochs, on the right side of the timescale, even those lasting tens of millions of years, represent the unique, random details in the meandering path of life on our planet.

  Yet what about the left side: the eons, the major life events of our planet? These are of particular interest to an astrobiologist because each represents a fundamental transition in the relationship between life and Earth. And each, I believe, is something we could legitimately search for on other planets.

  One of our main strategies for seeking life elsewhere operates on the suspicion that other atmospheres have been oxygenated by photosynthetic life. Perhaps this is geocentric thinking, but it’s hard for us to imagine that opportunistic evolving life would not plug into the
powerful and ubiquitous solar energy source. So we half-expect something like a Great Oxygenation Event elsewhere.

  Likewise, it is entirely reasonable to ask if other planets had a Cambrian explosion, or something like it. Indeed the question comes up all the time in astrobiology: should we expect only simple microbial life on other worlds, or larger and more complex organisms?

  One of the other big questions is whether we can find intelligent, technological aliens. For reasons I’ll delve into in the next chapter, we won’t be able to find intelligent life if it is only a brief phase, a flash in the pan. If we find other civilizations, it will be the ones who have made it through the bottleneck of technological adolescence. If technological intelligence is able to take hold, and become a lasting part of a planet’s functioning, this would arguably be at least as great a transition as any in Earth’s past. The moment where cognitive processes become a dominant mechanism of change is easily as significant as the oxygenation of the atmosphere or the advent of animal life. If global intelligence becomes a lasting planetary force, then I believe it is more appropriate to regard this as the beginning of Earth’s fifth eon.

  What should we call it? I propose the Sapiezoic Eon.

  Terra Sapiens

  When Carl Linnaeus, the great Swedish botanist who started our modern system of naming species, was coming up with a name for humans, he sought a quality that differentiated us from other, similar animals in the genus Homo. He chose sapiens from the Latin sapientia, meaning “wisdom.” Here he was echoing Charles Darwin, who wrote, “Of all the differences between man and the lower animal, the moral sense of conscience is by far the most important… It is the most noble of all the attributes of man.” Perhaps giving us this lofty title was a bit of overreach, of self-flattery, but it can also be seen as an aspirational goal, something we wish to be. And we alone are capable, it seems, of wishing or imagining ourselves to be something we are not, or not yet.

  If technological intelligence is to become, as life did long ago, a permanent part of the workings of our planet, it will be because we learned to integrate our activities gracefully with the ancient and deep dynamics of Earth. In chapter 2, I describe the debate over teleology in the Gaia hypothesis: the fraught question of whether the biosphere could possibly be said to be seeking some kind of homeostatic balance for its own good. With the Sapiezoic, we enter an era where Earth processes are unambiguously conscious and teleological, where life is obviously seeking, and finding, a balance among biological, geological, and cognitive processes, and where the boundaries between these, long identified as indistinct, fade to insignificance.

  In chapter 3, I make the distinction between cleverness and wisdom. Sapience (wisdom) differs from intelligence (or cleverness) in that it is not merely a kind of cognitive skill, but includes the ability to act with judgment born of experience. You can be intelligent but lack wisdom. You may be the best in the world at answering questions on IQ tests, or the cleverest solver of puzzles, but still lack the judgment to make good decisions. Wisdom is clearly something that some individual humans and teams of people (and possibly orcas and elephants) carry in abundance. Yet can we, humanity, collectively, globally, find wisdom? We’re in a phase characterized by our strong global influence, largely untempered and unmodified by our observations of the effects it is having. Can we make the transition to a phase of considered global control, where our actions result from an incorporation of all the knowledge we are gaining about the planet and its history, our history, and our growing awareness of the interactions between the two?

  This would be a changed world, and I have a name for it: Terra Sapiens, or Wise Earth. This is an Earth where we and the planet have both changed to come to grips with each other; where we’ve learned to live comfortably over the long haul with world-changing technology, applied with a deep understanding of planetary function; where intelligent and wise application of our engineering skills has become smoothly integrated into global processes. It’s a vision for the planet, but it’s also an aspirational name for ourselves, for who we must become to manifest this world. On Terra Sapiens we won’t differentiate between the two because we’ll identify deeply with the planet. We’ll understand that wise self-management and wise planetary management are one and the same.

  This may be wishful thinking. No, it is wishful thinking. I don’t see it as a forgone conclusion that we can achieve this new world where we’ve learned to apply our cleverness with wisdom. Yet it is by no means certain that we can’t. It’s valuable to have a vision of where we think we could conceivably be going. With the halting beginning of our mature Anthropocene, we tentatively dip our toes into this new eon.

  In calling such an era Sapiezoic, I don’t assume it will be humans (Anthropos) who will attain the wisdom to run a planet or, more accurately, to run with it. I suggest it as a more generic name for an eon when cognitive processes become a stable part of a planet’s functioning. It is when life, any life, realizes what it is doing and incorporates that knowledge into the operation of its planet.

  If we humans do not make the leap to sapient planetary management, other species may develop this ability in the future. Or, if we blow it this time, another human or hominid civilization may rise again, perhaps learning from our mistakes.* Earth may have a Sapiezoic Eon that does not begin with us. The term also need not refer just to Earth. Minds and machines are powerful and world changing. I believe they will sometimes appear on other worlds. Sometimes they will last, and these worlds will be transformed by them. Such planets will have a Sapiezoic Eon. When I think of SETI and the question of what it takes to achieve a long-lived planetary civilization, I imagine not just clever species with lots of nifty technology, but species who have also navigated the hurdles we are now facing, which have to do largely with discovering and redefining our relationship with our planet. I imagine worlds where technology has become an integral attribute of a biosphere, one that ensures longevity.

  I’ve argued that one way to approach the question “What is life?” might be to think of it as a property that a planet sometimes takes on. Similarly, mind may be a phenomenon that sometimes can become a property of a planet. If planets can have Sapiezoic Eons, then there is a form of stable intelligence, manifested on some worlds, that has not quite yet appeared on Earth. This might even help explain why we haven’t heard from anyone.

  6

  INTELLIGENT WORLDS IN THE UNIVERSE

  All is but a woven web of guesses.

  —Xenophanes

  We are scatterlings of Africa, on a journey to the stars.

  —Johnny Clegg

  A Common Story?

  Right now, we seem to be sleepwalking participant/observers in some new kind of planetary transformation. Could this be a local version of a stage in cosmic evolution where some planets start to wake up, look at themselves self-consciously, and at the same time look outward and wonder if they are unique? Maybe this perspective can help us in our effort to figure out what is going on here, and what our role is in this transition, and to awaken fully before we do too much damage.

  If we view the Anthropocene as the beginning of an unprecedented and significant transition in Earth history, then we naturally wonder if this has happened to worlds beyond. Yet when we try to imagine this same thing possibly happening to other planets, what exactly are we picturing? Obviously there are not going to be people. We don’t expect bipedal creatures driving metallic cars on asphalt highways between concrete cities, internal combustion engines suffocating their planet’s air with regurgitated primordial carbon. This isn’t a Star Trek universe with scattered almost-Earths peopled by almost-humans with tattoos and funny ears, possessing slightly different craniums, customs, fashions, spaceship designs, and architectural tastes. Evolution does not stamp out cheap replicas. As biologist Stephen Jay Gould famously surmised, if we could rewind and replay the tape of evolution on Earth, nothing like the modern biosphere, at least in detail, would emerge. To me this metaphor always seems strain
ed, since a tape recording plays back more or less the same every time. Evolution is more of a crapshoot, or a long series of them, run over and over again. What Gould meant is that it’s a random, contingent process, and the outcome is not neatly determined by the starting conditions. Given the chance, even on identical worlds, evolution would never repeat itself exactly. Now add in the fact that there surely are no identical worlds. As I describe in chapter 1, planets, even in the absence of life, are complex balls of feedback and chance, and in detail no two will be the same. So, the game of life will never be played with the same preconditions, and run in the same environment, even twice.

  There will be no people, but is there some essence of what people are that nonetheless can be expected, sometimes, to slither out of the mud of other home worlds, compelled by the same forces that brought us here? Are there common trends, inventions that evolution is bound to stumble upon? Life is so incredibly resourceful at finding ways to exploit environments to thrive and self-perpetuate. Natural selection is a ceaseless and thorough trial-and-error search for survival solutions. Certain innovations just work so well that they will always be found sooner or later. Many times in Earth history, life has independently hit upon the same survival tricks more than once. The similar aerodynamic swimming shapes in dolphins and fishes evolved completely separately. The octopus eye and the human eye are constructed in much the same way. Winged flight evolved separately in insects, bats, and birds. It seems the relentless, industrious incubator of natural selection has certain go-to solutions. Such convergent evolution suggests there may be a vaguely predictable quality to evolution that even spans worlds, not in the specific steps, but possibly in some overall trends.