Alive

I truly dislike the question “what is the meaning of life.” Not because I don’t see its importance, but because of the word buried in it that nobody checks. Life. What do we consider alive? How do we attribute to some things the property of being alive? Everyone asking what life means is sure they already know what it is. I’m not.

i. The biology of aliveness

From a biological point of view, being alive means an entity is a self-sustaining, organized system capable of processing energy, growing, adapting, and reproducing.

Let’s split this definition into smaller parts and see what we can say about each:

a. self-sustaining

I have a problem with the idea that an entity can be self-sustaining. How can something be self-sustaining? A human is clearly not self-sustaining — needs input from outside, from other entities. We need plants and animals for food, we need microbes and micro-organisms for the breakdown of nutrients in our gut, and we also need other humans for interaction. So a human is not self-sustaining at all; it takes an ecosystem to sustain a human.

What if we take something simpler? Is a plant self-sustaining? It clearly needs water, sunlight, and nutrients from the soil. At a simple glance it only needs things that do not depend on other living entities to get. But that isn’t true — a lot of the nutrients in the soil are made by other living micro-organisms, when they break down dead or living matter. Even if the breakdown were done by non-living entities, the logic would still break, since the dead or living matter being broken down was once living. And even if we argue the tree gets nutrients from its own leaves or bark, that poses a problem: how did those nutrients get there in the first place, when the tree had no leaves yet to shed?

Now, we may read that as a strawman argument. Self-sustaining clearly doesn’t mean “needs no external inputs” — it means the organism does the sustaining itself: it takes raw inputs and runs its own maintenance, repair, and organization without an external agent operating it. My problem is that this doesn’t work either, if we take the microflora in our gut as an example. Each of those micro-organisms carries a different set of DNA from you, and each will die without you, and you will die without them. So self-sustaining is a stretch for complex organisms.

Now what about simpler organisms, ones without this kind of symbiotic relationship?

We can go simpler than a free-living bacterium — a virus: a microscopic protective coat with a string of DNA or RNA inside. Still not self-sustaining. Its own reproduction depends on another living cell, into which it must inject its genetic material in order to reproduce.

So based on this, we can argue that self-sustaining is a stretch, and not a good representation of aliveness itself.

b. capable of processing energy

If self-sustaining doesn’t survive scrutiny, does the next word fare better? This is not a characteristic of aliveness, from the simple fact that multiple non-alive things have the ability to process energy. Take fire: it processes fuel into other components — waste and gases — releasing heat. A motor does the same, taking fuel and producing mechanical motion. A solar panel takes radiation from the sun and transforms it into electrical energy.

We can see that capable of processing energy is a characteristic both what we consider alive and what we consider not alive share. This blurs the line even more — we now know alive entities are neither self-sustaining nor the only ones that process energy. Let’s move forward.

c. growing and adapting

I will take these two together for convenience.

What does growing mean? From a biological point of view, a progressive, irreversible increase in an organism’s physical size and mass. This does not apply only to biological organisms, and it does not even apply to all living organisms.

My first problem is the word irreversible. It doesn’t hold for cells, for example — a cell increases in mass and size before reproduction, and once the mother cell splits in two, each resulting cell is smaller than the original was. The original cell loses mass and size. Or viruses: a virus’s size and mass are unchanged across its lifespan — it’s metabolically inert. Or humans: humans lose mass during starvation, so growth isn’t locked in one direction there either.

My second problem is that non-living entities also gain mass and size. A mountain’s size changes over time due to tectonic plate movement. A river increases in mass due to accumulation of water. Both examples work for decrease as well — mountains erode, rivers lose water and size during drought — but we already established irreversible isn’t the right word here regardless.

Now adaptation. It’s true that what we consider living organisms adapt to prosper or defend against outside stimuli, through evolution. But adaptation isn’t unique to life either. A river channel does something structurally similar: water finds the path of least resistance, that path erodes deeper, which makes it the preferred path even more, deepening it further — a feedback loop where the system’s structure changes in response to the pressure acting on it. Closer still: a machine learning model during training. Its weights change in response to an error signal, iteratively, in a direction that improves its fit to the data. That’s adaptation with a real mechanism — variation, a selection pressure, retention of what worked — the same skeleton as natural selection, minus biology. Nobody thinks the model is alive. If that counts as adaptation, adaptation isn’t sufficient for aliveness either.

d. reproduction

Only living organisms reproduce, right? Except a worker bee can’t reproduce — not broken, just built that way, her ovaries suppressed by the queen’s pheromones so the colony doesn’t collapse under everyone breeding. She’s not failing to meet the definition, she’s succeeding at being exactly what selection made her, and reproduction isn’t part of it. Same with a mule, sterile by chromosome mismatch. Same with an infertile human. On this logic, all of them stop being alive the moment they can’t reproduce, which nobody actually believes.

And it runs the other way too. A crystal in solution reproduces, in the plain sense — its structure templates onto new material, seeds propagate, more crystal grows exactly like the first. No life required.

Four for four. None of the criteria survive in-depth analysis. The parts of the definition of aliveness can’t explain the term they’re supposed to define.

ii. The lineage

What if the question is wrong? What if instead of asking “does this thing have the following properties” we ask “is this thing part of an unbroken chain of reproduction going back”?

We can trace back everything that we consider alive back to millennia, and doing this we also satisfy the idea that an entity that is alive also has the capacity to die — a state a mountain never enters. A mountain is not dead, will never be dead, so we cannot consider it alive now.

If we look at entities as having an unbroken chain of reproduction going back we do not have this issue. We can trace back everything that we consider alive to an ancestor, and that ancestor has another one. We take the example of humans here — we can trace back our ancestors to hominids, and those can be traced back to primates, and those to simpler mammals, and those mammals to earlier ancestors still. All of them now dead, having changed their property from alive.

At first glance the logic seems fine, but we run into a different issue in the regress itself. We can go back tracing an entity until we reach the first “alive” organism — but that one is the first thing that breaks the logic. It cannot be traced back to something else, since what lies behind it is prebiotic chemistry: a soup of chemicals that do not reproduce, that by some chance gave rise to this first organism and everything that followed.

There’s no first alive organism to point at — that’s the trap in the phrase itself. What actually happened is a gradient. Self-templating RNA that copies itself badly, then less badly, protocells that leak and re-form, membranes that hold together long enough to do it again. Reproduction wasn’t switched on. It got reliable by degrees, the same way a heap stops being a heap — no grain marks the line, no reaction marks the start. So the chain we traced back through every ancestor doesn’t end at a first link. It fades into chemistry that was already halfway there, and “halfway there” has no coordinates.

Which means lineage doesn’t fix what chapter one broke. It just moves the missing edge further back.

iii. Clusters

What if we looked at these properties, and the new one we found, as a cluster instead of a mandatory checklist? Nothing on the list has to be present. An organism counts as alive by how many of the properties it hits, not by hitting all of them. The mule fails reproduction and still scores on everything else. A virus scores maybe two out of five and sits in permanent dispute — not because we’re missing information, but because nothing says how many boxes is enough.

The cost is that “enough” has no number. Nothing sets a threshold for how many properties a thing needs to clear. That’s why a virus is an eternal argument and a mule isn’t — the mule scores high, the virus sits at the exact point where reasonable people split, and there’s no fact underneath waiting to settle it. The cluster doesn’t fail to answer that question. It explains why the question never had an answer to find.

Take a crystal. It reproduces, in the plain sense — its structure templates onto new material, seeds propagate, more crystal forms exactly like the first. One property on the list, clean, undeniable. And nobody puts it in dispute the way they put a virus in dispute. One box checked should land you somewhere near the virus, at the low end of the family, arguable. So either reproduction alone isn’t worth a box — which means the properties aren’t weighted equally, and now you owe weights, not just a count — or the cluster is quietly running on more than “how many boxes,” and it never told you what.

Take the simplest thing that still clearly fits. Mycoplasma genitalium, the leanest free-living bacterium we know — stripped genome, barely enough machinery to run. It still metabolizes, reproduces, holds a membrane, responds, keeps itself in balance. It hits the whole cluster with the least equipment anyone’s found, and nobody argues it’s dead. So the floor of clear life isn’t a low score. Even the simplest living thing hits most of the list.

Now the other direction. Fire. It processes energy, it grows, it spreads to make more of itself, it responds to what’s around it, it organizes into a moving front. Four boxes, maybe five — more than a virus scores. But we don’t consider fire alive.

So the count doesn’t track. The simplest life hits most of the list; a dead process hits most of the list too. Same tally, opposite verdicts, and the cluster has nothing to say about which side of the line either belongs on. Counting boxes was never what we were doing. It only looked that way because the clear cases happened to score the way our intuition already wanted them to.

iv. Conclusion

Alive is an edgeless word. It names a set of characteristics an entity might have — none of which it needs all of — and in the clear cases it works cleanly. A mammal hits every mark; a rock hits none. The word does honest work there, which is why we trust it. The failure only shows up when you scale across every axis at once: the simplest bacterium and a fire score the same, a virus sits forever on the line, the first living thing has no coordinates. Push the word to its edge and there’s no edge to find — just a slope, running from chemistry to us, with no grain that marks the pile.

And you never notice. That’s the part worth sitting with. The word feels solid your whole life because you only ever meet the clear cases. You never stand at the edge unless you walk there on purpose, dragging up prions and dormant microbes and crystals that copy themselves. The fuzz was always there. You just never had a reason to look.

Which brings it back to the question I started with. When someone asks what the meaning of life is, they say the word like it names a bounded thing — solid enough to carry a meaning the way a jar carries water. It doesn’t. The thing they’re so sure they’re pointing at has no edges. I’m not going to tell you life has no meaning. I’m telling you the confidence in the question is borrowed from a solidity that isn’t there — and once you’ve seen that, the question sits differently in your hand.