Humans must consume autotrophs, their products, and/or their predators to survive...

>Viruses don't eat you dumbfucks

Neither do animal cells. Our cells enslaved mitochondria to do that job for us.

If mitochondria can live outside cells, and we can't live without them, does that mean humans aren't alive?

There has to be an arbitrary cutoff, because life isn't "special." It follows the same rules as everything else, but we still find value in differentiating it from other things. For the record, I agree that viruses should be considered alive.

If your put a lion in a vegetable garden, it won't eat.
If you put a dog heartworm in something that is not a dog, it won't infect
If you put a bacteriophage in a petri dish of a bacteria it can infect, it will bind and reproduce.'

I don't see your point.

>requirement devoid of function or logic
Why? it's a definition. Cells are the building blocks of life by definition. We could've called carbon the building block of life, but we didn't. If you wanna call it arbitrary, fine, but then you basically have to call every single definition ever arbitrary. Look at SI units, many of them are based off of properties of water, who's to say water is so special?

>we hijack other organisms to survive
consuming =/= hijacking. If this was the case then only photosynthetic bacteria could be considered alive.

Viruses are just pieces that happen to fit exactly into certain parts of a cell and tell it to replicate itself. With the finite possibilities of sequences, this was bound to happen. A extremely precisely shaped rock may as well have done the same thing.

But if you must know, scientists use ALL of these traits to define if something is alive, iirc:
-It responds to stimuli.
-It evolves.
-It can reproduce asexually or sexually.
-It maintains homeostasis.
-It is constructed from cells or a cell.
-It can grow.
-It metabolizes.

Viruses aren't constructed from cells, they do not grow, they do not metabolize anything, they do not maintain homeostasis, and they cannot reproduce by itself or with a partner. Idk if viruses respond to stimuli or just kinda float around spastically. Viruses do evolve, however.

>what is anaerobic glycolysis
lmoa kill you're self

Like people said, it depends on your definition of alive.

If something can reproduce itself, it is alive in a sense. Viruses are complex enough to recreate something that is complex enough to etc etc.

You could say a computer virus is alive. When it comes down to it, comp viruses are just made of chemicals in your computer. And those chemicals are able to re-plant themselves and spread to other computers. The only difference is that bio-viruses can evolve, whereas a computer program does not mutate/evolve.

So they are alive. Computer viruses are alive, too. Can they comprehend pain, pleasure, freedom, physics, the fact that they are alive? That would take a more complex computer program/body.

Let me put it another way, until a viron binds to a host cell, it will remain inactive. A living organism will still respond to its environment. That's why Vincent Racaniello gets pissed when people anthropomorphize them and say stuff like "viruses employ, viruses do..." Viruses just float around waiting to bind to a receptor.

Another quirk about viruses is they crystallize under certain conditions, whereas no living things do so. ncbi.nlm.nih.gov/pubmed/21352920

They obviously respond to a stimuli, that stimuli being the presence of a binding site on the organism they infect.

It may be the only stimuli they respond to, but it is still a stimuli.

yes, they also evolve, but they don't fulfill all our requirements for being considered alive(totally arbitrary)

By that logic an electron is alive because it can respond to the stimulus of UV light exiting them to the next energy state, you aren't being philosophical, you're just being a dummy

electrons don't evolve, have a unique signature, create more electrons, and aren't organic.

>but then you basically have to call every single definition ever arbitrary
No, that's bullshit. Most species are categorized according to what physical characteristics they manifest, which is a very practical way of going about it. Your example of SI units being arbitrary is valid, but my point is also valid.

>If this was the case then only photosynthetic bacteria could be considered alive.
Yes, that is the logical conclusion of the point I was making and I stand by it. This requisite for reproduction to occur without taking ownership of another organism's metabolic processes is bullshit when we have to do that just to survive as human beings.

As to your other points: The cell requirement is devoid of logic, as I've stated. They don't grow, but why is growth a criterion when they are copied successfully regardless? And as to maintenance of homeostasis, why is that necessary when they reproduce regardless? I see no functional foundation for these requirements, just ass pulling.

and viruses don't metabolize, grow, reproduce sexually/asexually, or maintain homeostasis.

This. This is the biological equivalent of saying Pluto is a planet.

t. microbiologist

>viruses don't metabolize
They propagate chemical reactions that cause more of them to be made. What is your definition of metabolize and does it arise from a physical distinction or is it pointless and arbitrary?

>grow
See above.

>reproduce sexually/asexually
They fucking reproduce. See above about arbitrary defintions.

>maintain homeostasis
I am asking for functional reasons to include criteria, not circular logic. Saying that X is one of the criteria for life and thus Y thing isn't alive because it lacks X is fucking retarded when I've already explained that the criteria need foundation in reality.

OP here, I got what I wanted from this thread. I wondered if there was someone more educated than my idiot high school teacher who could provide practical reasons for using the current criteria for living organisms, but no one can. These criteria were pulled out of someone's ass and have no intrinsic value. Goodbye.

>Most species are categorized according to what physical characteristics they manifest.

So why aren't different breeds of dogs considered different species despite being dramatically different in physical qualities? Hmm... could it be because you are wrong?

>taking ownership
How is eating taking ownership... relying on another thing isn't the same as mimicking their functions for my own; If I ask someone to help me lift something, I don't slip inside of them and become them in order for them to lift that thing for me.

>devoid of logic
the logic was everything they've ever found to be alive had cells, so it seems to be a requirement for life. Viruses seem to be one of the only exceptions, but they don't exhibit almost any other qualities of life so we consider them abiotic and maintain the cell standard.

>why is growth a criterion
This requirement is basically a lemma of having a metabolism.

>why is homeostasis necessary
Good luck surviving anywhere without homeostasis.

>when they are copied successfully regardless?
>why is that necessary when they reproduce regardless?
Christ, is copying all that matters to you? I guess a fax machine or a computer virus is alive, too.
Viruses rely on other organisms for it's "reproduction". Humans only rely on other organisms for metabolic purposes, and if you want to be technical about it, we don't have to. Humans could live life and repopulate the Earth without ever killing or harvesting from a single living thing by chemically synthesizing carbohydrates, oils and proteins. We only eat living shit because it happens to be abundant in that stuff.

Viruses can be crystallized. Cells cannot because they constantly grow and carry out functions that cannot be interrupted because they are critical to its survival.

do viruses locally reduce entropy? can that used to make the distinction between living things and viruses?

>They propgate chemcial reactions that cause more of them to be made.
No, they don't? Cells do that. The virus is just along for the ride while the cell duplicates materials.

>See above.
Copying =/= growing

>They fucking reproduce
If I laid two perfectly "healthy" viruses side by side, would they be able to have an offspring? What about if I leave a single virus alone, would it replicate? Regardless of if that offspring would continue to exist, can it replicate? No, it cannot, an outsider cell is required.

Two healthy humans if left alone in a barren environment, can produce offspring. Despite the fact that the humans will die out, offspring can be made. Yes the human's would've had to eat other shit in order to be healthy, but since your point revolves solely around reproducing, lets look only at the element of reproducing since you seem enjoy disregarding all other factors besides this point.

>functional reasons to include homeostasis
Because things tend to happen to not only exist in areas of precisely 49.3 degrees celcius, 1.12 atm, with precisely 9.5hrs of sunlight present a day.

Rocks can live in nearly any condition on earth, so you could argue they are homeostatic, but they fail the other requirements.

>I got what I wanted
sounds like you wanted to be patted on the back for autistically spazzing out in front of your 16-17 year old peers in high school about something that has been discussed on a level much beyond you for the past hundred years, and were so upset that people disagreed with you that you sought comfort in internet friends but were disheartened to find that they think you are an arrogant idiot, too.

We invented these definitions. Life is most likely not some arbitrary easily defined concept. Are planets alive? Survival of the fittest applies to the formation of planets because of larger planets eating the garbage small objects in their path

Viruses are viruses, don't look too far into the definition of life for any reason except classifications which we find helpful as sentient, intelligent agents trying to figure out the universe

Some day maybe we will redefine life. I think eventually the "life" distinction will die out as a term and artificial intelligence will enter the same class as "life" because it will likely be sentient

I personally speculate that life is just a natural aspect of the universe itself, as intimately and deeply embedded as gravity and the specific subatomic particles we have.

i can understand why your teacher said they are not cell. As of last year (last time I gave a fuck ) virus are classified as acellular infectious agent. The term cell is usually reserved for the leaving.

REKT

Eh, when I was in school, they always taught us that viruses were in that "gray zone" between alive and not alive. Which, given how the checklist works, seems a reasonable statement.

Not that the checklist isn't arbitrary, yes, but it's fairly comprehensive, and ya gotta have some sorta working definition.

But I guess everything has to be black and white these days.

if you take a human cell and give it non-living matter (water, glucose, glycine) it can take that non-living matter and incorporate it into more living matter.
viruses, however, require not only the products of other living organisms, but the actual living presence of those organisms. viruses cannot reproduce in lysogeny broth, no matter what nutrients they are given; they must have actual living cells of other organisms there with them.

teal deer: it's not about trophic flow, but rather about homeostasis.

Are tardigrades alive, since their "homeostasis" conditions are far more open than any other universally agreed upon lifeform? Are purely parasitic organisms, like tapeworm proglottids, not "life" since they strictly require the presence of another living organism to carry out biological functions?

tapeworms can reproduce without a host
>asexual division
>if they were taken care of (say in a lab for example)
viruses can't do that

They still can't take in nutrients, and would thus die, without the presence of another organism. You could, in theory, make synthetic molecular structures that mimic the binding sites of a virus and chemicals present in the necessary lysomes it would expel its nucleic acid in an attempt to reproduce.

Species aren't categorized using physical characteristics anymore. Genetic classification is the new hotness.

in other words, by "taking care" of a virus, you could make it carry out its biological functions. Sure, maybe its just a chemical reaction compared to cellular respiration, but in that case the virus' "food" comes from energy released in chemical reactions that transcribe its nucleic acid.

>Sure, maybe its just a chemical reaction compared to cellular respiration, but in that case the virus' "food" comes from energy released in chemical reactions that transcribe its nucleic acid.
that's really not comparable.
a biological virus is alive in the same way a computer virus is an operating system.

I think some viruses put their DNA in a cells DNA then is able to hijack the proteins to make more viruses. So if a cell gets infected then multiplies one generation, there is now two cells produceing viruses. In fact sometime virues can spread through generations of multi celled organisms so scientists can see evidence of common ancestry between species. There is an example in chimps and humans I think.

>comp viruses are just made of chemicals in your computer. And those chemicals are able to re-plant themselves and spread to other computers

bro, are you dumb?

>chemicals?
>computer?

sheesh, charles babbage would kek about this post right now

>sounds like you wanted to be patted on the back for autistically spazzing out in front of your 16-17 year old peers in high school about something that has been discussed on a level much beyond you for the past hundred years, and were so upset that people disagreed with you that you sought comfort in internet friends but were disheartened to find that they think you are an arrogant idiot, too.
This post is the winner of the thread

If you are serious I think you might be retarded