Life as a cosmic Ponzi scheme. Part 2
A three-part meditation on the “meaning of life” at large scales. Part 1 highlights a surprisingly gruesome reality. Part 2 is about the trajectory of life on Earth and in the universe. Part 3 is on human progress and the bizarre moral dilemmas it creates.
Part 1 of this series had the ignoble job of tallying the scale of pain and trauma suffered by intelligent, mostly social beings in the daily business of life and death on our planet. It was pointed out that the multiple-orders-of-magnitude imbalance in the predator-prey relationship makes Earth’s biosphere — fondly referred to in metaphor as the “circle of life”— seem like nothing so much as a gratuitously cruel chamber of horrors.
Sidebar: why our metaphors about life matter
“The circle of life” — an image of balance, perfection and perpetuity — is just one of many popular metaphors disconnected from the reality of existence. The “gift of life” metaphor, for example, inaccurately calls to mind something wonderful and free (as in this elegant quip by Eleanor Roosevelt: “Tomorrow is a mystery, today is a gift. That’s why it’s called the present.”)
Whatever our individual affluent human experiences may be, life at large scale, i.e. in the aggregate, has none of the above attributes. Certainly in terms of the summed experience of sentient life as described in Part 1, a representative image might more matter-of-factly look like this
This is admittedly a harsh image of something we obviously all value. But if it’s discomforting, it brings up the question of why should our language and imagery about life even matter in the first place.
After all, it’s hardly news that life can be nasty, brutish and short. Why go to the trouble of deflating the few comforting narratives we have about it?
So before continuing to re-examine our metaphors for life at large scale, here is a case that it does matter. And probably this century more than ever.
To begin with, metaphors are much more than poetry. Our everyday mental universe would be virtually empty without them. Especially spatial ones like circle, edge, up, down, right, left, forward, backward, etc. are central to expressing all types of non-spatial, abstract ideas (perhaps consistent with connections between the motor cortex and language areas of the brain). Which metaphors we use in a given situation shapes our judgement, decisions and even measurable brain activity, according to recent neuropsychology studies. More generally, as cognitive linguists like George Lakoff argue, metaphors are fundamental to our very thought process. They are “the only way of understanding anything” in the words of psychologist Ian McGilchrist.
Their underappreciated power is as deceptively efficient engines for creating new mental content. As James Geary in I Is an Other writes “A metaphor juxtaposes two different things and then skews our point of view so unexpected similarities emerge. Metaphorical thinking half discovers and half invents the likenesses it describes.”
In effect, metaphors are miniature conspiracy theories. And like all effective conspiracy theories, effective metaphors provide an emotional anchor for entire belief systems. No wonder the ancient Greeks valued metaphors so highly in rhetoric, with Aristotle writing in his Poetics “To be a master of metaphor is the greatest thing by far”.
The most successful ones are culturally sticky enough to shape the worldviews of generations. Nietzsche being Nietzsche famously wrapped this into its own martial metaphor: “Truth is a mobile army of metaphors”. And of course, this entire account on metaphors is itself essentially a long list of metaphors.
All of which is a long way of saying: how we use metaphor to describe life matters greatly to how we live and treat other living beings.
Which finally brings up the main point of this sidebar. We humans in the 21st century have a particularly dangerous road ahead of us, but we also have more than our own lives to navigate. Like it or not, we now hold the trajectory of all life on Earth in our hands. And that may be just the beginning. If we survive this century to venture further into space, one day we could determine the fate of entire worlds. But will we be the builders of a galactic paradise or just be a plague of ravenous locusts? Will we know the difference, or for that matter, is there even a difference?
How will we see our place in the universe? What mobile army of metaphors will be our guides as we go forward?
These are not questions for the infinitely distant future. On Earth, the 6th Great Extinction is now. In space, from what we know about the durability of organic residues and even microbial spores, our interplanetary probes may have already set the seeds of living history for the next several billion years. And the technology for resource-extracting, terraforming von Neumann probes to plough up the galactic neighborhood is not all that far away.
If the story of life in the known universe now goes through us, isn’t the least we can do is make the effort to see beyond our human happy-talk metaphors? Don’t we owe it to the universe to try, to the extent we can, to see life in more universal terms?
Some metaphors based on entropy
The most universal thing we know about all life may sound dryly mathematical at first. But in another way it just captures a different type of poetic sentiment: that of a lost cause. From beginning to end, everywhere and under all circumstances, every living being is defined by its doomed mission to fight off the second law of thermodynamics.
Although Erwin Schrödinger is commonly cited for this insight, it was another iconic Austrian physicist, Ludwig Boltzmann, who had grasped the main idea in the 19th century: “…the general struggle for existence of animate beings is not a struggle for raw materials — these, for organisms, are air, water and soil, all abundantly available, nor for energy which exists in plenty in any body in the form of heat, but a struggle for entropy...”
Boltzmann was pointing out that while popular imagination may focus on matter and energy as elixirs of life (think all the times you’ve heard phrases like “life-energy”), neither are particularly special. The atoms in your body are just transient interstellar passengers, with 98% of them being replaced yearly. Calories blithely flow though your body regardless of what you do, whether alive or dead.
What is instead incredibly special and rare is order in the chaos of all this matter and energy. Like nothing else in the universe, a living organism is a master at creating and maintaining pockets of local order in an ocean of disorder — aka entropy — that surrounds and permeates it.
The web of metabolic tricks that evolved on Earth to pull off this incredible feat is what makes life here what it is. Individual performances of these tricks are what define our individual life histories. In fact everything about an organism — from maintaining its homeostasis to planning its next vacation — can be understood in this light. Although we tend to focus on the differences in genes, epigenes and environment from one being to the next, they’re just our particular messengers in the drama between order and disorder. From the smallest diatoms to the two legged creatures checking them out under a microscope — and to whatever might be lurking under the icy moons of Jupiter — our lives differ only in the entropy challenges we face.
The key point is that however its challenges are faced, every living being maintains its own order by dumping new disorder into its environment. All the while, the environment is dumping its own disorder back to the organism. But unlike matter and energy which are always conserved, net entropy is always increasing in these transactions. As Nietzsche might have put it, the price of life winning any battle with entropy is that it’s always losing the war.
A metaphor based on another type of transaction would be from finance. While the accounts of matter and energy are always balanced, entropy grows like compound interest. Life in this picture is not a gift but a high-interest loan. An organism spends the creative energy of its existence just trying to keep up with the interest payments. Some may be in a position to temporarily “do more” with their loan than others, but default is inevitable for all.
These are all metaphors dealing with life at the level of the single individual. More importantly here, the metaphor of a financial system also captures a critical aspect of life at large scale: periodic crashes of the whole system are inevitable.
But whether described in martial or financial terms, the second law of thermodynamics means that the true waste product of life is not matter or energy but entropy. In other words,
life’s mastery at creating order for itself comes at the cost of trashing the rest of the universe.
Life’s boom and bust nature
We can already get a glimpse of this with the granddaddy of all origin-of-life experiments, the 1952 Miller-Urey experiment. In simulating a possible early Earth atmosphere in a bottle, Miller and Urey were famously able to produce amino acids by electrically zapping a few simple gases (methane, ammonia, hydrogen and water vapor). That was an exciting breakthrough. But apart from this tiny amount of organic gold, what mostly appeared in their flask was a turbid toxic goo. So much goo that it would have choked off any actual metabolism before it could have ever started. Understanding how the earliest proto-life dealt with its own reaction waste products (sometimes called the “tar paradox”) is an important unsolved problem in the field of abiogenesis.
What is known is how life has dealt with its waste ever since: ecosystems. Ecosystems are, after all, just collectives of organisms that recycle each others’ trash.
Ecosystems are living reminders that entropy waste as such is neither inherently useless nor useful (a point sometimes forgotten in discussions in fields from ecology to economics). Whether entropy waste chokes its immediate environment to death or fuels its flourishing depends on what other metabolic tricks are available in the system for recycling.
The fact that entropy waste can sometimes be recycled and sometimes not is what leads to the boom and bust cycles known as speciation and extinction events.
The metaphors of Gaia and Medea
In the modern Earth sciences, these boom and bust modes of ecosystems have been personified in metaphor as the Gaia hypothesis (after the Greek goddess of life) and the Medea hypothesis (after the demi-goddess who murdered her children ) respectively. Unfortunately, Gaia and Medea are often portrayed as describing opposing views of how life on Earth works. But as mentioned above, they’re just complementary responses to life’s never-ending entropy challenges.
The Gaia view in its barest form is the indisputable statement that Earth’s current biosphere enjoys a measure of self-regulated stability. That is, our planet’s surface is not just randomly tuned within the Goldilocks zone for life as we know it. Rather, life’s efficient recycling of its entropy waste keeps the third rock from the sun roughly “just right” for itself.
The insight of James Lovelock and Lynn Margulis that mere biology can regulate surface conditions of an entire planet was astonishing at first. After all, Earth’s total biomass today is a mere 560 gigatons — barely a rounding error relative to the mass of the oceans (1.4 billion gigatons), Earth’s crust (25 million gigatons) and even relative to the atmosphere (5.5 million gigatons). That life can nevertheless do so is testament to its absurd thermodynamic efficiency at creating order and expelling entropy.
It wasn’t always like this of course. Earth four billion years ago was a semi-molten, semi-sterile rock that barely tolerated its few single-celled passengers. But today, the relationship is completely reversed. Life is now responsible for three times the energy input to the surface than what comes up from Earth’s deep molten layers. That energy flux makes the chemistry and physics of our planet what they are because of life. Ocean and atmospheric currents, even plate tectonics are what they are because of life. Roughly two-thirds of all known mineral compounds are either created or mediated by life. Already during the first eon of life, the Archean eon, single-cell organisms seem to have stabilized the continents through granite formation. All in all, this relationship between life and our planet’s systems is so profound that, instead of thinking about life evolving on Earth, it’s more accurate to say life and Earth have co-evolved together.
There are extended versions of the Gaia hypothesis that are not so indisputable. One extended claim is that life actually optimizes Earth systems for its own thriving. Further still, many see Gaia as expressing the idea that Earth (or at least the biosphere) as a whole is alive. Climatologist Timothy Lenton, for example, writes of Life on Earth with a capital “L”.
That last claim understandably triggers all sorts of woo-woo alarms. And perhaps it’s just another example of the emotional power of metaphor. Nevertheless, I personally don’t think that has to be an inherently unscientific point of view. Seen as a unit, Earth does carry the thermodynamic fingerprint of life. It takes in energy from the sun and spews entropy into space at a rate that keeps the planet in a highly ordered state far from equilibrium.
One could even argue that Earth carries other signatures of life, such as those recently proposed by Stuart Bartlett and Michael Wong for life writ large (dubbed “lyfe” in their nomenclature). Specifically, Earth as a whole could be said to actively maintain homeostasis (i.e. Gaia behavior) and engage in learning (what else is evolution, if not learning?) Bartlett and Wong additionally propose reproduction as a signature of life, but personally I don’t think that has to be decisive. Mules and worker bees don’t reproduce either.
Either way, since we don’t really have a better idea of what life “is” to begin with, one might well ask “why not see Earth as an organism?”
That’s all well and good, except that a lot of high-order organizational structures also fit these descriptions. Human societies actually fulfill all of the above criteria better than our planet, but should we really see them as living beings? If so, should we say that each different society is alive separately? Where would we even draw their boundaries across geography and time? My personal conclusion is that our current characterizations of life (or lyfe) may be the best we have so far, but for a strict definition are still missing something.
In any case, even the weaker Gaia claim that life is able to optimize planetary conditions for itself holds at best sporadically and approximately. As a general rule, natural selection isn’t in the business of optimization. Lest the perfect become the enemy of the good, surviving and procreating means kludging together just-good-enough-in-the-moment solutions to fight another day.
More generally over the long run, the optimization claim doesn’t hold across Earth history. For one thing, if it were true in that simple form, one would expect the total biomass of the planet to grow or at least stay constant. In fact just the opposite seems to have been going on for the last 540 million years. From its then estimated peak of about 1,200 gigatons, models show the total amount of carbon captured in all living organisms has actually declined by half since complex multi-cellular life appeared with the Cambrian explosion.
The Medea view in its barest form is the indisputable statement that life can sometimes be its own worst enemy. That is, sometimes the biosphere’s homegrown problems grow faster than natural selection can innovate metabolic solutions for them. That usually doesn’t end well for the biosphere. Our own anthropogenic climate change and the 6th Great Extinction can be seen as just the most recent example.
The earliest known example can be seen today in the spectacular red rocks showing banded iron formation. These alternating bands of iron oxide and quartz are a direct record of a rapid-fire series of boom and bust cycles that together made perhaps the greatest extinction event of all, the Great Oxygenation Event (GOE) 2.5 billion years ago. That was when the first truly efficient photosynthesizing microbes — cyanobacteria, aka blue-green algae — set free the atmospheric oxygen we enjoy today. In the process it gave the oceans their blue-green color by precipitating out iron oxides to form the red bands in these special rocks. Unfortunately for the vast majority of life at the time, oxygen was toxic and so they vanished forever. The layers of silicate quartz between the iron in the banded rock formation are a witness that even the cyanobacteria were periodic victims of their own success. At least until they evolved the right metabolic tricks to tolerate oxygen.
To be sure, free oxygen set the stage for complex multicellular life in the long run, but that leap forward would first have to wait a while. The initial drop in CO2 levels and temperatures from all that photosynthesizing were followed by the Earth becoming a frozen snowball for the next 300 million years in a phase known as the Huronian glaciation.
Clearly Earth has often been anything but hospitable to life, with a geological time stamp riddled with extinction events great and small. The not-so-undisputed claim of Medea hypothesis is that life itself is almost always the culprit. Climatologist (and originator of the Medea metaphor) Peter Ward calls this life’s inherent “suicidal tendency”.
For example, Ward and collaborator Joseph Kirschvink cite the Carboniferous Rainforest collapse 300 million years ago. It came at the end of the Carboniferous Period that gave the industrial world its massive coal reserves. Coal deposits happened because nature couldn’t innovate lignin-eating microbes fast enough to break down the newer species of trees that were taking over. Instead of being released back into the atmosphere, their carbon got buried, leading to another period of glaciation and extinction.
To be sure, the causes for almost all extinction events are still hotly debated. Non-biological explanations often center on volcanic mega-eruptions, as evidenced today by great landscapes of ancient flood basalt layers or “traps” that are found around the world. Eruptions at these scales released enormous amounts of toxic gases and particulates into the atmosphere. The effects on climate would have also been dramatic, if complicated. Historically known eruptions from Vesuvius to Pinatubo have had a short cooling effect on the planet because their sulfate particulates reflect sunlight back into space. In fact the worst natural disasters in history, like the collapse of Bronze Age civilizations; the extreme weather of 536–537AD that blanketed the Northern Hemisphere in fog; and the “year without a summer” in 1816 — are all generally believed to have been driven by volcanic eruptions.
But these have also all been brief, one-off events. Eruptions lasting millions of years like the ones that produced the vast Siberian traps, and quite possibly the Permian-Triassic extinction (aka the “Great Dying”), would have spewed tens of thousands of gigatons of CO2 into the air. Even the dinosaur-killing asteroid impact 66 million years ago was accompanied — coincidence or not — by massive volcanic activity that made the Deccan traps in central India. Since CO2 gas persists much longer in the atmosphere than particulates, the longer term net effect of these eruptions would have been a sweltering hothouse of a planet.
In another scenario described by Ward and collaborators, truly massive extinctions began when volcano-driven greenhouse effect caused the oceans to warm at the poles more than at lower latitudes. This eventually halted the global circulations that are driven by latitudinal temperature differences. This in turn deprived the waters of oxygen — terrible for fish but a bonanza for anaerobic bacteria. Specifically, Sulphur-spewing bacteria like chlorobiaceae thrive in such conditions. Its waste product hydrogen sulfide H2S is highly toxic to almost everything else it comes in contact with. For humans, a mere 100ppm can be fatal. Levels of H2S during extinction events, at least in these scenarios, would have made much of the planet surface somewhat like the trenches of WWI during a gas attack.
Life on Earth is expected to have a finite lifespan
Be that as it may, there is a general consensus in the Earth sciences that Earth’s biosphere on the whole has a finite, self-imposed lifespan. In fact, on its present trajectory — at least without humans in the mix — the total biomass of all life on Earth is slated to continue its current decline to essentially zero sometime within the next 1.5 billion years. The reason is one that can only strike us today as tragicomic. There will not be enough CO2 in the atmosphere.
Even at its worst, this anthropogenic emissions might discombobulate the climate up for some few thousand to a few million years. The far bigger process is driven by the exactly what we wish we had more of today: photosynthesis.
The genius of plants and other primary producers is that with only sunlight, water and a few helpful minerals, their food can be literally pulled from the air, i.e. CO2. With a metabolism like that, it’s no wonder that they make up the lion’s share of Earth’s biomass (more than 80%). But in being so efficient in removing CO2 from circulation, over the eons they’re steadily depriving the planet of its protective blanket and main food source. Some 95% of plants use a photosynthetic metabolic pathway called C3 that requires at least 150ppm of atmospheric CO2.
In the 500 million years before the agricultural and industrial revolutions, Earth’s atmosphere had been slowly trending toward this limit. Based on this dynamic, Lovelock himself published the first estimate of the biosphere’s remaining lifespan to be about 100 million years. More recent estimates with more sophisticated models — and taking into account the 5% of plants that use the more recently evolved C4 pathway and can get by on much less CO2 — place the time until universal extinction between 800 million and 1.5 billion years.
On the other hand, who knows what metabolic tricks natural selection will pull out of its hat before then, or what the effects will be. Some 2.5 billion years ago, the one-time metabolic miracle of oxygenic photosynthesis appeared. That turned sunlight into an infinite resource, and the cyanobacteria that mastered it flourished. In the process they became the ultimate Medean species; their toxic waste caused mass extinction on a scale that almost sterilized the planet. But it eventually gave Earth a biosphere with oxygen and complex multicellular life; perhaps one of the few or only one in the galaxy.
Some 300,000 years ago another one-time miracle of sorts appeared. A group of primates left the forest and developed their own infinite resource: computationally open-ended language. That let them imagine infinite possibilities to dominate this one. Not surprisingly then, this species too is driving a mass extinction and paving the way for some new biosphere. That future may or may not include homo sapiens and might even be based more on semi-conductors than carbon. If so, we can only guess at the mobile army of metaphors that will be deployed.
All we know is that which events in Earth history are “good” or “bad” — which species are more “Gaian” or “Medean” — depends on which side of the extinction event you’re on.
 Which in turn seems to makes sense if the ability for a conscious train-of-thought is a direct neural descendent of physical movement, as proposed, e.g. in the confabulation theory of the mind by the late Robert Hecht-Nielsen.
 The mechanism for that seems clear from the brain’s job of information processing. Unifying distant concepts into a single narrative is a giant leap of data-bundling. That’s a huge advantage for a brain always looking to tie neat algorithmic bows around otherwise hopelessly large data packages. “Successful” data-bundling tools like metaphors must activate the brain’s reward systems like the dopamine pathway. That neurochemical rush is the quiet fit of delight when we feel we’ve understood something new and important. It also reinforces the neural pathways that lead to that belief in the first place.
 For plants and animals alike, breathing is the main pathway for exchanging matter and energy with the environment. In humans, exhaling CO2 accounts for about 84%.
 It’s unfortunate that Medea is mostly known for her filicide, a story that seems to have been an invention of Euripides that later authors took up. In earlier stories like Jason and the Argonauts, she is a brilliant thinker and tech-wizard who more than once saves the day.
 It’s efficient enough to create a thermodynamic signature on a planetary scale visible from space. This, in any case, is how James Lovelock and others predicted in the 1960s that Mars was barren, well before the Viking missions of the mid-1970s . Unlike Earth, the Martian ratios of gases like carbon dioxide, nitrogen and oxygen were known to be in chemical equilibrium. (Methane was discovered in 2004, but at levels so low and irregular that it’s unclear if it could be biogenic) It was this observation led Lovelock to the original Gaia hypothesis, further developed with microbiologist Lynn Margulis.
 After the Swedish trappa for “stairs”
 Some have speculated the weather of 536–537AD might have served as the inspiration for the Norse myth of Ragnaroek.
 The year also saw the last widespread famine in the West. While seeking shelter from the unusually harsh weather in June 1816, Mary Shelly, Lord Byron and friends spent the time in a Swiss villa inventing horror stories that became the origins of Frankenstein and Dracula.
 Some hypothesize that the asteroid impact sent shock waves throughout the planet to trigger the Deccan trap volcanic eruptions.