In my opinion, a virus in the environment is quasi-dead, but once it enters a cell and it hijacks its components, it becomes alive.
This does not differ that much from bacterial or fungal spores, or even from plant seeds, which can also be almost "dead", i.e. without detectable metabolism or internal changes, even over many thousands of years, until they reach a favorable environment that triggers their revival.
The difference between a virus and a bacterial spore is that the viral particle contains only a subset of the parts of a living organism, so it could never be brought back to life in an environment where nothing is already alive. However, once the virus takes control over many parts of a cell, which provide the functions that it is missing, like the machinery for protein synthesis, the ensemble formed by the parts brought by the viral particle and the parts formerly belonging to the invaded cell, can be considered as alive and distinct from what the invaded cell was previously.
In any case, the evolution of the viruses and the evolution of the cellular forms of life are entangled, with a lot of genetic material exchanged between them, so considering the viruses as non-living is definitely counter-productive, because neither the viruses nor the cellular forms of life can be understood separately.
The word you're looking for is cryptobiosis/anabiosis no need to invent a new one. Something thats later alive almost by definition is not dead. The entire living system has been alive since abiogenesis.
We have to agree on the basic definition of ultra-basic terms.
You just proposed a definition. Good. It's not complete, but necessary, conditionally.
Basically, we shouldn't use "alive" and "dead" as dualities. There's at least three states: "dead/inert/never gonna get there", "meets a definition of life (see next category) when supplemented by a host cell or something else complex and exterior", "can self-replicate and grow on its own, in a friendly environment with sufficient food/fuel/inputs available = life".
Maybe more. But let's stop pretending biology is dead versus alive, because viruses definitely ruin that.
That's a pretty cool framework for the alive or dead debate. I've always been firmly on the alive side but now I can do a better job of presenting the argument concretely instead of just ' nuh-uh '
> so it could never be brought back to life in an environment where nothing is already alive
I always thought of a virus as purely a "modifier", not having the characteristics of "life" independently. If this was a game, the virus might be a runestone or skin for your character.
Anything that doesn't need external "life" to come alive, I would consider as "life" in various states. Maybe it's in hibernation, or stasis, or dormant but the life is there. Maybe to keep the silly game analogy, this might be the extra character on your roster.
Yes but you are talking about the threshold of existence, and the cell is alive as soon as it starts existing. For a virus you also have the threshold of "application", when the viral code is applied to something alive. Before that the virus exists but is not alive itself. After the application it's modifying other life which maybe technically can be considered alive.
This is why I said "to come alive" instead of "to be created". The virus is something that just exists but only becomes alive when mixed with something that's already alive.
Most concepts in biology break down on the borderline cases, because the phenomena are so complicated with all the little variations, the concepts have an inherent fuzziness.
Instead of the concepts being like a box where something is definitely in the box or not in the box like in mathematics or maybe physics, the concepts are more like a clustering of characteristics in a high-dimensional space or landscape of variation, where things are classified according to their similarity to a central paradigm case. (This seems to be how our minds model at least some concepts as well, as evidenced by our being faster at categorising cases that are closer to some paradigm case)
One notorious example is the concepts of male and female: yes, there are borderland examples of individuals who can't be classified as either, but almost everyone clusters sufficiently closely to the distinct paradigmatic cases that the concept has an obvious utility.
But the same thing happens everywhere in biological classification: whether something is a mammal or not becomes fuzzy as we go back in evolutionary time, and whether something is alive or not is similar.
Sure, but considering how central and defining the concept of "life" is to biology (the study of life and living organisms) you'd think we wouldn't have a fuzzy definition for that specific concept. I can see why it's tricky, though.
Life is very useful as a term because it allows you to define a 'not living' term as well: dead. And it has meaning at the highest level. But if you start looking at things in a more detailed way even death doesn't arrive 'all at once' for multi cellular organisms, for instance a dead person's hair still grows to the point that corpses need to be shaved. And a virus may be dead by one persons view on what 'life' is all about but alive by someone else's definition. And depending on the context both of them may be right.
The definition is fuzzy because the concept is fuzzy! Even something that we in every day life see as settled such as a species is not always clear-cut. Cat or dog? That's usually easy. Member of a species yes or no? Not so easy, and in some cases subject to considerable debate and even then unresolved.
It is misconception that hair and nails continue to grow. What happens is the that kind and soft tissues dehydrate and shrink and the hairs and whiskers stick out more. Growth stops soon after oxygen and nutrients stop being delivered.
We really only have one example of life (or at least all our examples are interconnected), so I don't expect great definitions.
Just like geology doesn't have a great definition for their subject of study (the earth). They have a definition that works really well, but because they only have one example, the definition ain't stress tested.
Slightly less silly: it took the discovery of lots more bodies inside and outside the solar system (dwarf planets here, exoplanets elsewhere) for astronomers to really nail down the definition of planet.
I think that depends on your prior expectations about how biological concepts should be structured. I was trying to make the case that we should expect that they're fuzzy when we're dealing with very complex phenomena that exhibit a lot of variation. The fact that these kinds of phenomena happen to exhibit clustering is what makes (fuzzy) classification possible, but we also find that many phenomena or organisms are in borderland areas between clusters, so the classification doesn't work as well with them.
The problem is that it's really hard to come up with a definition that includes all of the things we agree are obviously life (e.g. mold), does not include fire, and does not just appeal to the particular structure that most or all life on earth seems to have (the cell).
The result is a landscape of fuzzy definitions mostly centered around that last one.
We only have a single tree-of-life (or possibly, several syncretic trees-of-life from a single planet) as an example. Makes it a little difficult to discern the true principles.
> the concepts are more like a clustering of characteristics [...]
> This seems to be how our minds model at least some concepts as well [...]
Since we have existed for 100's of thousands of years, and formal thinking only a couple hundred as a widespread practice, only habitually by a modern minority, and then for a tiny minority of daily concepts -- that is very nearly the only way we encode concepts.
In fact, we no doubt actually encode formal concepts using clustered characteristic thinking. We have just intentionally narrowed characteristics down to the point that the result is formal thinking.
Yeah, I think that's an interesting feature of linguistic thought: it builds on and exists within our deep evolutionary heritage of percetion and fuzzy classifications, but by the nature of words as being discrete items it also predisposes us to think naively that the phenomena referred to by words are also discretely organized into this box-like either/or structure, but the reality is more complex
Spoken words forced/helped us divide up completely fuzzy concepts into discretized hierarchies of less and less fuzzy concepts over time.
And then written symbols, enabled a trend of identifying more and more simple I.e “primitive” abstract concepts (culminating in true, false, 1, 2, 0, infinity, node, edge, …) that let us reformulate and better understand complex fuzzy concepts as compositions of primitive concepts.
> Most concepts in biology break down on the borderline cases
Most concepts break down on borderline cases, within and without biology. Those motivated will abuse this to argue that those concepts don't meaningfully exist at all.
Because in most cases the categories are invented by us, to make sense of the world. But the penomena themselves are often continuous. Or actually not just us but most life with some kind of sensory system - even paramecium differentiates between food and non-food.
Take our color perception as an obvious example: We clearly see different types of color, despite us being unsure at the thresholds in between, and the actual electromagnetic radiation of visible light being a continuous wavelength range.
That is just a fundamental limit of our reasoning. We mentally make models of the world to make sense of it. These models have to be of less complexity than reality, ergo they have to cluster perceptions, ergo we have to categorize.
Similarly, the standard definitions of intelligence break down when we look at borderline cases like simple algorithms, collective insect behavior, or AI systems.
Viruses particularly exemplify “intelligence” is better understood as a spectrum of information-processing and adaptive behaviors rather than a strict threshold.
The issue seems to me that neither concept is wrong, but that we humans keep trying to impose absolute definitions on phenomena that exist along continua, blurring into one another in ways that resist our neat little categorizations.
I would argue viruses exemplify some of the highest evolved intelligence in our world.
If you dropped me off in vacuo (eg in deep space), I wouldn't meet the definition of "alive" either. But the fact that my life require a specific environment doesn't phase us or challenge our definition of life at all.
Not only do I need certain physical conditions (temperature, pressure, molecular gas composition, etc), but I also need to eat, so actually me being "alive" is dependent on specific biological conditions too. My Minimum Viable Environment actually includes other organisms, yet this doesn't challenge the fact that I'm defined as alive.
Certain parasites can only live or reproduce within another organism. This is even more extreme, but it still doesn't challenge our definition of them as being "alive."
This new organism requires a specific "environment," and that "environment" happens to be inside another organism. So what? We're totally un-phased by this requirement when it occurs in other examples.
Perhaps it's better to think of this not as a spectrum between alive and non-living, but as a hierarchy of how constrained (vs unconstrained) is the "environment" required to support life processes.
Useful, but not exact. To go more general in biology. It's kind of like classical pre-cladistics taxonomy. It's helpful to have a definition of reptiles that excludes birds, sometimes, even if birds are evolutionarily reptiles, sometimes you might only want to talk about the cold-blooded species today.
This is just another way to say that the map is not the territory. Anything that tries to describe reality in simpler terms than actual reality is likely just going to end up being a leaky abstraction rather than a hard law. And nature is very fuzzy along the boundaries of whatever concepts you are going to come up with.
