The Life Origin Rabbit Hole

Where we get a little more speculative with our origin theories.

I. What Is Life, Really? The Definition Problem

The deepest rabbit hole of all is also the most basic: nobody has a definition of life that everyone accepts, and the failure is itself informative.

Every proposed definition either lets in things we want to exclude or excludes things we want to include. Define life by metabolism, and a candle flame (which consumes fuel, grows, and produces waste) sneaks in, while a dormant seed is left out. Define it by reproduction, and a mule (sterile but unquestionably alive) is excluded, along with much of the worker caste of social insects. Define it by response to the environment, and a thermostat qualifies. Add Darwinian evolution as the criterion, popular among origin-of-life researchers, and you get closer, but you exclude any single isolated organism considered on its own, and you struggle with the very transition you are trying to explain, since the first proto-life was presumably not yet evolving in the full sense.

We simply have not found the right definition yet. There is no sharp line because life is not a binary property but a continuum, a matter of degree, and the question “is it alive?” is sometimes as malformed as “is this a heap of sand?” asked of a few grains. If life is something matter does more or less of, rather than a switch that is on or off, then the search for the moment non-life became life may be looking for a boundary that does not exist in nature, only in our categories. This connects to the LUCA & the Energy Bubbles concept of life as encapsulated energy-processing: that is a definition by degree, not by kind. The possibility that the hardest question in the section is hard partly because it rests on a category we invented that nature does not strictly honour.

Categorisation is exclusionary, and yet we need it to communicate. 

II. Viruses: The Edge Case That Breaks the Categories

A virus is a scrap of genetic material in a protein coat. On its own, it does nothing: no metabolism, no energy processing, no reproduction, no response. It is, by most criteria, not alive, no more alive than a complex crystal. Yet when it enters a living cell, it hijacks the machinery and reproduces, evolves, adapts, and behaves for all the world like a living thing engaged in a parasitic strategy. So is it alive? It depends entirely on where you draw a line that nature does not draw for you.

 Are they degenerate descendants of once-free-living cells that threw away everything but the essentials of replication? Are they escaped fragments of cellular genomes that took on a life (or “life”) of their own or an exosome gone rogue? Or are they relics of a pre-cellular world, survivors from before the boundary between living and non-living had settled, still straddling it? Each possibility carries different implications for how we think about the origin of life, and the question is open. The virus is not a special weird exception to an otherwise reasonable concept; it is a standing reminder that we are still guessing.

III. The Abiogenesis Hypotheses, Pushed Further

The core problem with all origin-of-life research is that it is trying to reconstruct a singular event (or a class of events) that happened around four billion years ago, left almost no direct trace, and may have proceeded by chemistry we have not yet thought of. Researchers can show that a given step is possible under plausible conditions (amino acids can form, RNA-like molecules can self-assemble on clay, protocells can divide), but showing that something is possible is a long way from showing it is what actually happened. The field is rich in proof-of-possibility and poor in proof-of-history, and may remain so, because the evidence is largely gone.

The various “first” candidates beyond RNA and metabolism, such as the proposal that clays or mineral surfaces served as the original templates for organising molecules; the “lipid world” idea that self-assembling membranes came first and chemistry organised within them; and the “thioester world” and other metabolic-first variants. None is established. These are not really rivals to be adjudicated so much as fragments that the eventual answer may stitch together, and that the answer, if it comes, may look like none of the current candidates. All we can do is hold genuine interest in all of these while conceding that we may never know which, if any, is right, because the past does not always leave enough evidence to reconstruct it.

IV. Predictive Life: The Free Energy Principle Revisited

Even a bacterium forms internal molecular representations of its environment and uses them to anticipate conditions, swimming up a nutrient gradient before it arrives at the source. In a minimal sense, the cell predicts. The Free Energy Principle, associated with Karl Friston and met in Emergence & Complexity, proposes that any system that persists must act as though it models its world and works to minimise surprise, keeping itself within the narrow band of states compatible with its survival. On this view, life is fundamentally a predictive, inference-making process, from the bacterium reading a chemical gradient to the brain forecasting the next moment, all the way to your senses and even your gut lining anticipating what is coming. Some thinkers extend this to a “Bayesian brain,” in which the nervous system is essentially a prediction engine, constantly generating expectations and correcting them against incoming data.

If it holds, it would unite the origin of life, the function of cells, the operation of the nervous system, and the nature of mind under a single principle: persistence through prediction. The observation that living systems from cells to brains are deeply predictive is real, well-supported, and genuinely illuminating; the claim that a single formal principle underlies all of it, from abiogenesis to consciousness, is a stimulating and unproven frontier idea. The predictive thread is taken up again, on the side of the mind specifically, in Consciousness, Free Will, & Meaning. Here it earns its place as one of the more ambitious attempts to say what life essentially is: not just energy-processing, but energy-processing that anticipates.

V. Dissipation-Driven Adaptation Revisited

Recall Jeremy England’s proposal: when matter is bathed in a flow of energy, it may tend, statistically, to arrange itself into configurations that capture and dissipate that energy more effectively, and the structures that do this best are exactly the kind of self-organising, energy-channelling systems that life exemplifies. If correct, this would mean the emergence of life-like, energy-dissipating organisation is not a freak accident but something matter is thermodynamically nudged toward under the right conditions. Life, on this view, would be in some sense what energy-rich matter tends to do.

If dissipation-driven adaptation is right, the origin of life starts to look less like winning a cosmic lottery and more like a probable outcome wherever you have energy flow, the right chemistry, and time, which would suggest life is common in the universe. If it is wrong, or only weakly true, the origin of life may remain a rare fluke. This is an elegant hypothesis, grounded in solid thermodynamics, and it is not established, with the leap from simplified model systems to the actual origin of life unproven, but it is the clearest current candidate for a principle that would make life probable rather than miraculous.

VI. Inevitable, or a Fluke?

The inevitabilist view holds that life is a natural, probable consequence of the right physical and chemical conditions, so that wherever those conditions exist, life will tend to arise. The dissipation-driven-adaptation idea, the relative ease of forming life’s building blocks, and the speed with which life appeared on Earth (almost as soon as conditions allowed) are taken as support. The flukist view holds that the origin of life, or at least some crucial step in it, was extraordinarily improbable, a one-off accident that might happen only once in a galaxy, or once in a universe.

The evidence genuinely cuts both ways, and a crucial complication comes from Energy Factories: Nick Lane’s argument that the hard step may not be the origin of life at all, but the origin of the complex cell. Simple life appeared on Earth almost immediately, which looks like evidence for inevitability, at least for simple life. But the complex cell took another two billion years and appears to have happened only once, which looks like evidence that that step, the one that made animals and us possible, was the genuine fluke. This splits the question productively: it may be that simple life is common across the universe and complex life is vanishingly rare, that the galaxy is full of bacteria-equivalents and nearly empty of anything that could wonder about it. We do not know. But the structure of the question, simple life easy and fast, complex life slow and singular, is one of the most suggestive patterns in all of biology, and it connects directly to the next cluster.

My Ill-informed Hypothesis: I would imagine that all life is, is a lipid bubble of contained amino acids that get bound to the outer membrane, which creates a location for manageable ion exchange. The inner contents of the bubble have a different electromagnetic charge than the outside of the bubble, creating a chemical and electrical gradient that drives a “desire” for equalisation/homogeneity. The amino acid formation/peptide chains bound to the membrane facilitate the conformation of packaged energy, like ATP, which can be used as currency for molecules to engage with. To me, anything beyond that is an adaptation due to the most basic process of “predator vs prey” interactions. Predators would possibly contain the equivalent of a glutamate receptor on the outer membrane that causes a muscle-like contraction towards the collection of amino acids being leaked into the local environment by a potentially weakened bubble of goodies. Whereas, a prey-like state may involve something similar to a voltage-gated calcium ion channel being triggered by electromagnetic activity in the vicinity. Drawing in calcium from outside the primal cell would facilitate “escape” from an oncoming predator with early-peptide chains operating like actin and myosin in a muscle. These two early-state versions of fear and growth would result in the emergence of more complex states. Keep in mind that consciousness is not required at this stage. Although I would argue that this would suggest that the onset of consciousness is not necessary either. Just because we have defined consciousness as the cause of our summised perception, it doesn’t make it real. It is only, so far as I can tell, a term used to soothe our desire for meaning.     

VII. The Great Filter and Are We Alone

The Fermi paradox asks why, in such a vast and old universe, we see no sign of anyone else. One influential suggestion of the possible answers is the Great Filter: the idea that somewhere on the long road from dead matter to a visible, communicating civilisation, there is at least one step so improbable that almost nothing makes it through. The question is where the filter sits. Behind us, or ahead?

If the origin of simple life is the filter (if abiogenesis is the near-impossible step), then we are through it, and the universe is mostly empty because life seldom starts. If, as Lane’s argument suggests, the origin of the complex cell is the filter, then simple life may be everywhere and complex life almost nowhere, and again we are through it, exceptionally lucky. Either of these is, in a strange way, good news: a filter behind us means we have already passed the hard part. The unsettling possibility is that the filter lies ahead, that the hard step is not making a civilisation but surviving as one, in which case the silence of the universe is a warning. Nobody knows which of these is true, and the origin-of-life question is one of the main places we might eventually find out, because pinning down how hard it is for life and then complex life to begin would tell us a great deal about where the filter sits. This is speculation, clearly marked as such, but it is speculation anchored to real and active science, and it is the point where the humble question of how a cell first formed becomes the question of whether the cosmos is full or empty, and what that means for us.

VIII. Panspermia at the Speculative Edge

The modest, defensible version (that organic molecules and perhaps hardy microbes can travel on comets and meteorites, and that life’s ingredients may have been seeded from space) has genuine evidence behind it and is taken seriously. Directed panspermia, the idea that life was deliberately seeded by some prior intelligence, was floated semi-seriously by figures including Francis Crick, and it is essentially untestable and explanatorily empty, since it relocates the origin of life to an unknown elsewhere and an unknown intelligence whose own origin is unexplained (similar to the concept of the movie Prometheus). More interesting is the genuine scientific question of whether life on Earth and any life elsewhere in our solar system (on Mars, or in the subsurface oceans of certain moons) might share an origin, having been swapped between worlds on impact-ejected rock. If we ever find life elsewhere in the solar system, the first crucial question will be whether it is related to us (a shared origin, spread between worlds) or genuinely independent (a second, separate origin), and the answer would transform our estimate of how easily life begins. A truly independent second origin, even of microbes, even next door, would be one of the most consequential discoveries in history, because it would strongly suggest life is common. The territory here is less about believing panspermia and more about recognising that the traffic of material between worlds is real, and that it complicates the tidy picture of life arising once, in isolation, on a single planet.

IX. Open Research Questions

• How did life actually begin? Replication first, metabolism first, or both together?
• Where did it begin: hydrothermal vents, surface pools, or somewhere else?
• Is there a workable definition of life, or is “alive” a matter of degree with no sharp boundary?
• What are viruses, in origin and in status: alive, not alive, visible, or a category error?
• Is the origin of life probable (inevitabilism) or a fluke, and does dissipation-driven adaptation make it probable?
• Is the hard step the origin of life, or the origin of the complex cell?
• Did life arise more than once on Earth, with only one lineage surviving?
• How far does the predictive, Free-Energy-Principle account of life actually reach?
• Where is the Great Filter: behind us, or ahead?
• Is there life elsewhere, and if found, would it share our origin or be genuinely independent?

X. Future Topics

• The detailed chemistry of specific abiogenesis pathways (formose reaction, the citric-acid-cycle-first proposals, mineral catalysis)
• Astrobiology and the search for biosignatures on other worlds
• The subsurface oceans of Europa and Enceladus as candidate habitats
• Extremophiles and the true limits of life on Earth
• Synthetic biology and the attempt to create life in the lab (which would prove a pathway is possible, though not that it was the historical one)
• The deep relationship between the origin of life and the origin of information
• Whether a “shadow biosphere” of unrelated life could exist undetected on Earth
• The thermodynamic definition of life in more rigorous detail

XI. . Resources Bridge

• On the origin of life and the energy-centred view, Nick Lane’s The Vital Question is the essential starting point, with Power, Sex, Suicide for the mitochondrial story.
• On the chemistry-to-biology transition, Addy Pross’s What Is Life? How Chemistry Becomes Biology for the dynamic-stability framing of the definition problem.
• On the deep history and the predictive-life thread, Joseph LeDoux’s The Deep History of Ourselves for the four-billion-year arc from cells to conscious brains.
• On dissipation-driven adaptation, Jeremy England’s Every Life Is on Fire, held with the calibration from the entropy page.
• On the are-we-alone and Great Filter questions, the rare-Earth and Fermi material in The Universal Rabbit Hole, and the resources noted there.

XII. Cross-Links

• Life Origins for the section overview
• LUCA & the Energy Bubbles for the abiogenesis hypotheses and the definition of life
• Evolution & Genetics for the mechanisms and major transitions
• Energy Factories for the complex-cell-as-hard-step argument
• Origin Terminology Cheat Sheet for definitions and the progression of life
• Resources for the reading list