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Nietzschemouse t1_jbowwcd wrote

Reply to comment by Nymaz in I just learned that the known shortest DNA in an “organism” is about 1700 base pairs in a certain virus. Is there a minimum amount of “code” required for an organism (or virus) to function in any capacity? by mcbergstedt

Eh. Not really any more than there is a concrete definition of "species".

Lots of biologists don't refer to viruses as organisms, but there's a fair argument that they're no less alive than any other parasite.

I'd say, noting this is tangential to my field of study, that the (EDIT: agreed upon) minimum requirement is a cell membrane. Viruses may have capsules, but it's not quite the same. I believe this to be unnecessarily arbitrary, but it's consistent with keeping viruses out of the alive category

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InfamousAmerican t1_jbp0ugv wrote

Would replication of RNA/DNA not be sufficient to be considered an organism?

I see why the parasite/virus case is similar. Does the difference stem from the necessity of a host for viral replication?

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ayelold t1_jbp4m0g wrote

Viruses don't have a metabolism. Generally speaking, using energy is part of being alive. Also, a virus doesn't replicate its own DNA. It co-opts the replication mechanisms of a host cell and forces the cell to do the replication.

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rickdeckard8 t1_jbp714o wrote

There are no easy dividers like these to separate life from non-life. The short answer is that it depends on how you define life. Others define it in another way and include viruses among live organisms. Just like there is no clear definition on what a game is.

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Nietzschemouse t1_jbp3fdp wrote

In my opinion, that's enough, but the taxonomists of the world disagree.

There are so many organisms that are obligated to have a host to survive. Granted, they mostly need one condition or another that the host provides, rather than invading its cells, but I much find the distinction between virus and obligate pathogen to be just one that is being held onto rather than one that is meaningful. I'm open to someone giving me a real definition, though I've never encountered one I feel satisfying.

Worth noting, my opinion on the lack of consensus for species is that there genuinely can't be one. Humans try to classify biology, but biology doesn't care. You can look at the clostridium or clostridioides clades or the bacillus cereus groups and see examples of biology laughing at us trying to name a species when there is so much intermingling and genetic transfer or so little genetic difference between "species". Dengue virus subtypes might be even clearer, though that's an example of what should arguably be four species being lumped into a single one. Also, why would a non living entity be granted living entity taxonomy like "species" or "genius"? I think that's a matter of convenience, but it does raise an eyebrow because viruses have evolutionary histories as rich as bacteria or animals.

Then there's the "there's no such thing as a tree" argument, that I personally subscribe to.

Long story short, between understood "convention", attempts at classification (taxonomy) that can only approach but never reach the truth, the complicated phylogenetic nature of the world - the fuzzy line between the same and different, and the general resistance to change, I don't think there's really a clear answer for what constitutes an organism and why. Again, I'm open for debate or education.

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CreaturesLieHere t1_jbq7yb9 wrote

I think the answer lies in quantum physics, we may find some mechanism there that exists in typical life but doesn't exist in atypical thing like viruses and self-replicating RNA. Either that, or it lies in chemistry and we just haven't found the right experiment to make the discovery with. Because the line between "a mix of compounds/elements that can do complex things" and "life" has to be drawn somewhere right?

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TheNorthComesWithMe t1_jbqhi7s wrote

There doesn't have to be any fundamental measurable difference between something that is or is not life. Reality doesn't really care about our need to define things.

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Elladan71 t1_jbrmf6j wrote

This is undeniable. But when we're talking about definitions, aren't we talking about human constructs, attempts to approximate truth? Isn't it the same impulse that birthed the scientific method? Drawing lines between things is *useful!

Plus, anything that provides conversation like this thread is worth talking about, if you ask me.

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CreaturesLieHere t1_jbqo3rx wrote

There are several measurable differences between cells and viruses.

Defining what viruses are, and thus whether or not they're considered "life", is quite scientifically important. We need to define things based on what their uses and limitations are. Viruses are already known to have unique characteristics; if we further define those characteristics and are able to distinguish them from organisms, we can potentially discover new things about life, or new things about almost-life as a whole that fits certain parameters. We dont know what we don't know. Everyone freaking out over labels is missing the point, as usual.

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Nietzschemouse t1_jbq98ao wrote

I mean, sure. Maybe such a thing exists, but if we don't know of that, we're just making things up.

Not that it matters, but I don't personally draw a line between a bunch of molecules and an animal. Granted, that's not a common opinion

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blacksheep998 t1_jbp6ca6 wrote

There exist self-replicating strands of RNA. All they are is RNA in solution that can gather and assemble loose nucleotides into copies of itself.

But if a virus is alive, then they could probably be considered alive too.

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omgu8mynewt t1_jbphzq3 wrote

I work with viruses, some virologist like 'genetic material replicating and closed in a membrane' which makes me laugh

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