Okay, this got me curious. From the wikipedia article on viruses:
Viruses are considered by some biologists to be a life form, because they carry genetic material, reproduce, and evolve through natural selection, although they lack the key characteristics, such as cell structure, that are generally considered necessary criteria for defining life. Because they possess some but not all such qualities, viruses have been described as “organisms at the edge of life” and as replicators.
I’m no scientist but I’d say, “Do it reproduce? Do it evolve? Do it try to survive? Bruh, it’s alive.”
I’m no scientist though. Just an idiot watching thangs. :p
It seems to fail the last criteria there. They don’t actively escape or react to predation. For the most part they aren’t actively “trying” anything other than to just float around and replicate.
It can’t reproduce on its own, though. It needs a living cell to do that.
Do it reproduce?
Not by themselves, no. They need to take over a cell’s replication machinery for that.
Do it evolve?
Yes, as they are subject to natural selection.
Do it try to survive?
I don’t think so, they don’t try anything to do anything, they just are… but the same can probably be said for most actually living organisms, including many relatively complex ones, so I don’t think it can be used as a way to determine if something is alive or not.
Most interesting definition, I think, comes from contrapposto. Can it die? No. So long as it retains its “shape” more or less, it functions. If heated or denatured, it no longer functions. More like broken than dead.
But it did reproduce then no? Its just like how some organisms are surviving as a parasite. They need another thing to survive mostly as food. But in this case, as a reproduction method.
The thing, though, is… you take a virus, put it in a petri dish by itself, and it does… nothing.
It doesn’t have a metabolism, it doesn’t look for a host, it doesn’t do anything… it’s just an inert clump of organic matter. (Then again, probably the same could be said for, say, spores. Or pollen. Or raw DNA or even RNA. Are those alive…?)
But plug it into a cell and… well, it sort of breaks apart, injecting it’s RNA or DNA into the cell, and… that’s it for that particular instance of the virus.
Sure, the cell will then take that genetic payload and unwittingly use it to fabricate as many copies of the virus as it can… but at that point the original virus instance is just an empty protein husk… is it still alive…? Does “being alive” maybe not apply to individual virus particles, but to this whole process…?
Maybe being alive is not just a binary, but a scale (or something more complex) where you can fit anything from crystals or prions to us and who knows what else, maybe whole ecosystems, maybe the Gaia concept of a living world…
But we humans certainly do seem to like our black and white binary choices, even if viruses might be a triangular peg we’re trying to fit into either a round or square hole…
I agree, the point is that we need to define “alive” itself clearly which as you stated, is currently beyond our understanding.
If being inert constitutes as not living then yes, virus is not alive. Their “evolution” is not because of their doing/needs but rather due to their construction. In that case I think virus is more akin to a poison. The substance itself can be not dangerous, but due to a metabolism process inside a specific organism/cell, it becomes a dangerous substance. The side effect in this case is just so happens to make another copy of the virus. But this process is prone to mutation as their building block is quite prone to do so, and we get the “evolution”.
Yours is the reply I like the most.
They’re not compromised of cells, can’t self regulate, and can’t replicate on their own and other organisms have to do that for them. The last point being important to our criteria for living. I was never taught as a biologist by anyone that they were alive
There you go defining humans as not alive again
There are plenty of organisms we generally consider “alive” that can’t replicate or do other key functions without other organisms.
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Like what? Sorry my comment posted so many times my phone was messing up
For reproduction purposes, many parasites require a specific host to reproduce in. An interesting example is a worm that mind controls a snail and gets itself eaten by a bird, and then reproduces in the bird. Surprisingly, both the snail and the bird survive this process. (Granted, the difference between this and a virus is the virus uses the RNA decoding infrastructure in the infected cell to reproduce itself, while a parasite just is adapted to reproducing in the environment of the hosts body, but uses its own cells to do the reproduction).
However, there are many, many examples in nature of some essential task (often some part of the energy production/absorption process) that are done by a different organism. Some particularly interesting examples:
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there are a handful of animals that eat plants, absorb the chloroplasts, and use those to do photosynthesis
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In most animals, even in humans, a lot of the digestion process is done by bacteria living in your digestive tract. Some illnesses are caused by issues with the digestive tract bacteria, such as them dying out.
There are other animals adapted to living in environments or using things produced by other organisms. Hermit crabs get their name from their behavior of borrowing shells created by other organisms.
Really the only organism that can truly live “by itself” would probably be something like algae.
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Theoretical biologist here. I consider viruses to define the lower edge of what I’d consider “alive.” I similarly consider prions to be “not alive,” but to define a position towards the upper limit of complex, self-reproducing chemistry. There’s some research going on here to better understand how replication reactions (maybe encased in a lipid bubble to keep the reaction free from the environment) may lead to increasing complexity and proto-cells. That’s not what prions are, but the idea is that a property like replication is necessary but not sufficient and to build from what we know regarding the environment and possible chemicals.
I consider a virus to be alive because they rise to the level of complexity and adaptive dynamics I feel should be associated with living systems. I’ll paint with a broad brush here, but they have genes, a division between genotype and phenotype, the populations evolve as part of an ecosystem with all of the associated dynamics of adaptation and speciation, and they have relatively complex structures consisting of multiple distinct elements. “Alive,” to me, shouldn’t be approached as a binary concept - I’m not sure what it conceptually adds to the discussion. Instead, I think it should be approached as a gradient of properties any one of which may be more or less present. I feel the same about intelligence, theory of mind, and animal communication.
The thing to remember when thinking about questions like this is that when science (or history or literature…) is taught as a beginner’s subject (primary and secondary school), it’s often approached in a highly simplified manner - simplified to the point of inaccuracy sometimes. Many instructors will take the approach of having students memorize lists for regurgitation on exams - the seven properties of life, a gene is a length of dna that encodes for a protein, the definition of a species, and so on. I don’t really like that approach, and to be honest I was never any good at it myself.
Thanks for posting this! While my knowledge of biology is quite limited, it’s always great to get an informed person’s take on an interesting topic.
Wildlife biologist here, and I have to concur with just about all of this.
I think we generally look at a viruses and consider them alive but just barely. While prions are not because they (proteins) are what is considered one of the building blocks for life. Self replication being one of the major criteria we’d look for. We look at a very macro level of life but our education and work has a strong overlap down here a well.
This is such a well written post! Gets the point id like to make across in a much better way than I could
Worth mentioning: life is a construct created by humans. We decide if it’s alive, just like we decided if anything else was alive. There’s no definite answer that science can provide on this topic. It can only provide humanity with more facts with which we can contrive a distinction.
Yes, everything is a social construct and reality is fake and bad
We’ve given life a set of repeatable rules that create a definition. Viruses don’t meet the rules.
Perhaps an artifact from an earlier abiogenesis event that cannibalized itself before our own evolutionary tree started?
ok i’m not a biologist but having a cell structure as a prerequisite for defining life sounds very arbitrary to me.
Maybe undead ? That would explain all those viral zombie apocalypses.
fungi are extra alive somehow
I swear Fungi are an alien species, they’re so weird
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What are you talking about? I’d like a citation for that.
DNA in all eukaryotes is composed of adenine, thymine, cytosine, and guanine. RNA in eukaryotes subs in uracil for thymine.
There are things that make them substantially different from other branches of life, but not in that way.
Absolutely not true. Fungi are weird but not this weird. Citation please
How so?
Some have features of both plants and animals, so they’re kinda hard to fit into rigid categories.
they’re neither plants or animals, so… what does that have to do with being extra alive
That’s how I interpreted @moosetwin@lemmy.dbzer0.com ’s “extra alive” phrasing. If you want to know exactly what they meant, I recommend asking them.
Do prions count as another secret fourth thing?
Nah they’re a single molecule. While they do have a mechanism to “reproduce”, they cannot react to stimuli of any kind, or evolve. Of the 7 commonly accepted traits of life, viruses have 5-6 depending on where you stand with them not being able to reproduce on their own. (In comparison, while a tapeworm or other parasite might need a host, they bring their reproductive equipment with them).
Prions have 1 of those traits. They can’t regulate an internal environment as they cannot have one, they lack any kind of organizational trait, they have no metabolism (the other one viruses lack), they do not grow, they don’t adapt to their environment, and they do not respond to stimuli.
A digital thermometer has organization and responds to stimuli, so it’s more alive than a prion.
If viruses aren’t alive because they don’t have their own reproductive equipment, then neither are men
Evolution came up with sexual reproduction as a mechanism to keep the gene pool varied and varying. In this sense the female and male sexual organs constitute one single reproductive apparatus.
Another ingenious mechanism is the bee/flower or fly/flower or bat/flower, duos of completely separate species in beautiful, poetic symbiosis. Birds with seeds is another one.
The bees (or flies or bats) reproduce on their own, but the flower has turned those species into part of its’ own reproductive organs, in a way.
Is this what some virus really looks like? It looks like Tron-era CGI.
Artist’s view of bacteriophages, viruses that infect bacteria and look like this. They attach to the bacterial wall with these fibers that look like spider legs, and then inject their DNA into the bacteria by contracting the sheath that attaches to the DNA-containing head. They kinda work like a syringe.
They almost seem like just a “living” reproductive system, as if that’s the entirety of their existence. Like real-life Daleks going “IN-SEM-IN-ATE!”
The image is in fact CGI, but yes there are several viruses known as bacteriophages that look like this.
Trying to find this confirmed electromagnetic scan of this phage led me down a truly fascinating rabbit hole about antibacterial phage therapy, taxonomy, and more. Let your curiosity take the better of you on Wikipedia
Such awesome pictures
Yes, this is a bacteriophage. Truly fascinating stuff I’m lucky to work with every day.
More or less yes, that’s the type of virus we learned about in biology class at least. Although there are various shapes a virus can have. Like covid that is round or other viruses that look more like bacteria.
Yes, I’ve always thought of bacteriophages as giant death robots of the virus world
Evidence of a false dichotomy to me
The third thing would be “inanimate”
Which is essentially Latin for “not alive” so 🤷♂️
There’s a difference between dead and non-living though. Dead implies it was alive previously
While technically phages are viruses, i think it is important to label them as phages.
Typically a virus does not look like a robot. The by now rather well known SARS-CoV-2, with its spherical shape is a more common depiction of a virus: https://en.m.wikipedia.org/wiki/Virus
Bacteriophage look like little robots and from the view of a bacterium - they probably are the equivalent of a terminator: https://en.m.wikipedia.org/wiki/Bacteriophage
But phages are the most ubiquitous form overall. Maybe not as relevant if you mean viruses that infect humans.
Schrodinger’s biology?
The replicators are real. I still think the version from Stargate SG-1 are the scariest though.
Oh great virus! What is your wisdom?
R E P R O D U C E
Nice, thanks
This little doodad reminds me of Jenova Chen’s old freeware game flOw. Fun little game, but iirc it isn’t free anymore.
Love his games, Journey is still one of my top 10 gaming experiences of all time.
I loved flOw and Flower, but I still haven’t played Journey, I need to get a good ps3 emulator just for that. Also I just checked and the 2006 “student” version of flOw is still free, the 2007 ps3 version is paid.
Its in steam now and works even better than the original ps3 version! Its also 70% off right now :0
Ehhh I guess I need to figure out steam/proton then lol. I haven’t played games in years. Is Flower up there too?
Edit: Thanks for all the advice on steam/proton everyone!
Not much to figure out, just make sure to not get the flatpak/snap. Any non-arcane distro should have a working package, the trick to packing steam being not trying to be smart about things you basically have to give it a libc, gpu, and FHS (chroot or not), it takes care of everything else.
It is! They’re both steam deck verified so they should run on proton!
I’m just a quirky little lad.
Ok protein spooder
I found this to be interesting. The word (and concept) of a virus predates its actual discovery by over 500 years.
The English word “virus” comes from the Latin vīrus, which refers to poison and other noxious liquids. Vīrus comes from the same Indo-European root as Sanskrit viṣa, Avestan vīša, and Ancient Greek ἰός (iós), which all mean “poison”. The first attested use of “virus” in English appeared in 1398 in John Trevisa’s translation of Bartholomeus Anglicus’s De Proprietatibus Rerum. Virulent, from Latin virulentus (‘poisonous’), dates to c. 1400. A meaning of ‘agent that causes infectious disease’ is first recorded in 1728, long before the discovery of viruses by Dmitri Ivanovsky in 1892.
I knew iOS was poison
I can’t find anything on the 1728 claim, but I remember hearing that Louis Pasteur coined the term while studying rabies in the 1880s!
