The definition of living by most biologists wouldn't include a strand of genetic material. Fire replicates in particular environments, as do viruses. But we don't typically classify either as living.
I think the point you're getting at is that the distinction between living and non-living is a bit arbitrary and meaningless. I agree.
Fire and viruses have an important difference though, when fire replicates, its children don't inherit anything. A better example would be crystals as their structure influences crystals they seed.
the operational definition agreed on in mainstream science is that to be living, you have to do regulated metabolism. This definition mainly exists to distinguish viruses from cells; I'm sure there are even cells which don't metabolize, but those are exceptional cases in which the ability to metabolize was lost in a parasitic situation.
Spiegelman's monster isn't alive under any common definition of alive, but it has fascinating properties nonetheless and appears to be an attractor in the RNA sequence space, which is quite interesting on its own.
Presumably because it can't act? There are two relevant paradigms to consider:
- Diamonds move through the earth (since the earth itself is not static), grow, and split. This means they move and reproduce. Are they alive?
- Prions are proteins that reproduce directly, by bumping into other proteins and forming them into prions. Are they alive?
The general run of thought that I'm familiar with is that bacteria are unambiguously alive, viruses are ambiguously alive, and diamonds are unambiguously not alive. Prions would go somewhere on the scale between viruses and diamonds. I would personally rate the monster below prions in terms of "being alive"; it doesn't surprise me to see it called "pseudo-living".
Anyway,the question of "where is the line when life begins" is subjective and scientifically boring. It's only interesting philosophically to people who don't understand the concept of spectrum/gamut/continuum. The interesting question is where specimens fall along the spectrum of completely inert to complex life.
Viruses are mechanically simple enough that the conceptual toolkit of chemistry is enough to understand them. But the conceptual toolkit of biology, while not necessary, can still be fruitfully applied to them. (Biological understanding is also necessary for explaining why viruses might do what they do.)
There is no "not alive" category; that is the long-discredited philosophy of vitalism. It's purely a question of how you choose to do your analysis.
But I'll leave you with a selection from the wikipedia article "Virus":
Opinions differ on whether viruses are a form of life, or organic structures that interact with living organisms. They have been described as "organisms at the edge of life", since they resemble organisms in that they possess genes, evolve by natural selection, and reproduce by creating multiple copies of themselves through self-assembly. Although they have genes, they do not have a cellular structure, which is often seen as the basic unit of life. Viruses do not have their own metabolism, and require a host cell to make new products. They therefore cannot naturally reproduce outside a host cell – although bacterial species such as rickettsia and chlamydia are considered living organisms despite the same limitation. Accepted forms of life use cell division to reproduce, whereas viruses spontaneously assemble within cells. They differ from autonomous growth of crystals as they inherit genetic mutations while being subject to natural selection.
Sure, but one could make the same argument about any life on Earth. If considered in the context of the galaxy, our planet is pretty much as rare and well tailored for us as a test tube is for the monster.
"Living" is one of those things that is hard to pin down an exact definition for because there are so many edge cases.
Is life on earth everything that processes sunlight, directly or indirectly? Well solar panels do and microbes subsisting on energy released from deep sea vents don't. Is sexual reproduction the defining characteristic of life? Plenty of examples to the contrary of life forms reproducing in other ways.
It's actually really hard to find a precise definition that doesn't have an exception.
As for the Spielgelman's Monster, if this were to be described as living, that would mean man had created "life" from non-living matter, that would be rather big news.
Well the article says its not even self replicating. It requires humans to do much of the work of providing specific machinery and materials that it needs to make copies of itself.
But it also doesn't do much. That's a nebulous, hard to pin down statement. But I mean it doesn't have all the complex machinery and behaviors of living cells. It's static and kind of just floats around. Until things happen to bump into it and stick.
It's not fundamentally different than a virus. Which are also self replicating, but I don't think they are considered "living".
Heh, we must have been posting at the same time. Good point that the RNA monster doesn't do much; even some bacteria can "smell" chemicals and move along a gradient, a "behavior" that makes us think of them as alive. I wonder if you could get behavior like that with just rna
I haven't read anything about this besides the Wiki but I would say the RNA monster's not alive because it only reproduces when a scientist adds the right enzyme to the test tube. It can't actually reproduce itself. Viruses on the other hand contain genes in their rna for proteins (both enzymes and the structural proteins that make up their shells) and so they can reproduce by hijacking some cell's protein synthesis pathways.
