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FZ+
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Well then, are they or are they not?
selfAdjoint said:Alive involves movement, metabolism and reproduction. One-celled animals like prokariotes do these things on their own. Viruses have no metabolism and their reproduction depends on the structures of the cells they prey upon. Some of them do move independently.
So I put NOT. The other category seems a cop-out; clearly even very simple bacteria are alive, and also clearly viruses don't do - independently - all the things a linving organism is assumed to.
chroot said:Some people have theorized that viruses were developed by some ancient form of bacteria as a weapon against other bacteria. I don't know the current scientific validity of that theory, but it makes sense. Something living (and with RNA at least) had to make the first virus, since it couldn't have made itself. If you don't believe that a bullet or a missile is alive, then neither is a virus.
- Warren
Jeebus said:The question poses too much definition in terms, I suppose. No one here is going to agree 100% of what alive, dead, or neither actually consists and constitutes of.
Often the debates about wether a virus is alive or not is really a debate about what constitutes "alive", without the participants even knowing it
You see, I have a problem with this argument. Nothing does all the things a living organism is presumed to, independently. Plants need sunlight, for example. Humans need to eat. Animals usually need females, or males. Why can't we say that viruses are living carnivores, which feed on uninfected cells and digest them to function?So I put NOT. The other category seems a cop-out; clearly even very simple bacteria are alive, and also clearly viruses don't do - independently - all the things a linving organism is assumed to.
FZ+ said:You see, I have a problem with this argument. Nothing does all the things a living organism is presumed to, independently. Plants need sunlight, for example. Humans need to eat. Animals usually need females, or males. Why can't we say that viruses are living carnivores, which feed on uninfected cells and digest them to function?
Loren Booda said:Viruses are biological uncertainty.
In biology, the only certainties are death and taxis.
Think of the permanent stasis of viruses as occupying an otherwise unfulfilled niche. Also, not wasting energy on metabolism for processes like active motility can prove most efficient. One may thus think of a virus as utilizing statistically random currents to navigate its environment.Very funny Loren. I hate to encourage such pun-ishing contributions, but . . . how do you explain life's relentless, less-than-Checkered march toward adaptive-taxis while viruses are content to sit there "exempt" from change for eternity?
LW Sleeth said:There is general consensus that life is a self-sustaining system that metabolizes, multiplies, and has the ability to evolve. Because technically it can be said that a fire, for example, metabolizes and multiplies, I like the delimiter John Maynard Smith and Eors Szathmanry gave in their book "The Origins of Life." They said we might define as living ". . . any population of entities possessing those properties that are needed if the population is to evolve by natural selection. That is, entities are alive if they have the properties of multiplication, variation, and heredity (or are descended from such entities; a mule cannot multiply, but its parents did). . . . Why should we regard these three particular porperties as defining life? It is because they are necessary if a population is to evolve all the other characteristic we associate with life."
A virus, by even less of a definition than that, fails to show it is alive. Left on its own, it will not multipy, it will not variate (constructively), and of course it will not pass on genetic material. It can do nothing until it enters a living system, which then merely reproduces the virus and reacts to the virus. True, the virus can mutate, but it can only do that once it enters the living system. Remember, the genetic material of a virus came from formerly living cells, so we shouldn't be surprised that programmed into it is an adaptive trigger. Because a virus cannot mutate on its own, we have to assume it is the living system itself which is providing the impetus to pull that trigger.
A virus is not alive!
Loren Booda said:L W Sleeth Think of the permanent stasis of viruses as occupying an otherwise unfulfilled niche. Also, not wasting energy on metabolism for processes like active motility can prove most efficient. One may thus think of a virus as utilizing statistically random currents to navigate its environment.
Jeebus said:As I said, no one here is going to agree 100% on what life consists of exactly. So far.
In summation, I think you can safely say that [virusues] because they require the metabolic machinery of host cells to survive, and contain genetic material, you can say they both have living and nonliving characteristics.
Imparcticle said:How does a virus behave outside of a host?
LW Sleeth said:The thing is, the aspect of "aliveness" doesn't show up until a virus enters a host everyone agrees is "alive." Isn't that suspicious?
So, what most defines "aliveness"? Is it the machinery of a biological form or is it the dynamism? Even the simple, organelle-less prokayote exhibits dynamism. In fact, when we observe a "dead" thing, we see all the machinery is present, but it has lost its dynamic-ness. Even if we agree that it's the machinery alone which produces that dynamism, it's loss nonetheless makes the thing dead (and a living being's dynamism can endure through the failure or loss of a great many machine parts too).
That's why I can't see what to make of the lack of dynamism in a virus except that it isn't alive itself, and is only animated by something that is alive. I suppose someone might argue that the virus is made alive by its host, but to me then we have to include my bicycle as alive while I ride it.
Jeebus said:Good point. But prokaryotes lack a nucleus. The organelles of eukaryotes allow them to exhibit much higher levels of intracellular division of labor than is possible in prokaryotic cells, so division of prokaryotes aren't quite sufficient to substitute in for a virus, … I think.
Jeebus said:A bicycle is an inanimate object, it isn't quite the same as a virus because it lacks genetic material and it can't reproduce, so you would need to find a better example to fit the same criterion as a virus.
Jeebus said:I see your point, and agree almost whole-heartedly, but as I said earlier without the definition of what life consists and constitutes of; no one here is going to ever agree on a 100% definition of what life is.
FZ+ said:Nothing does all the things a living organism is presumed to, independently. Plants need sunlight, for example. Humans need to eat. Animals usually need females, or males. Why can't we say that viruses are living carnivores, which feed on uninfected cells and digest them to function?
Don't also chemical (chaotic) clocks a la Prigogine's nonequilibrium thermodynamics?Everthing exchanges information and energy and under casually efficacious circumstances, complexity increases. Changes in the physical state of viruses and there higher hierarchy, meet these conditions.
Loren Booda said:Rader Don't also chemical (chaotic) clocks a la Prigogine's nonequilibrium thermodynamics?
LW Sleeth said:You caught me being lazy there . Okay, what if my bicycle wheels were connected to a belt that ran an assembly line which robotically produced other bicycles.
Imparcticle said:Jeebus:
What is the difference between "to produce" and "to construct"?
This is a common question that arises when discussing viruses. The answer is not straightforward, as there is ongoing debate among scientists about whether viruses can be classified as living or non-living. Some argue that viruses meet the criteria for life, such as the ability to replicate and evolve, while others argue that they lack essential characteristics of living organisms, such as the ability to maintain homeostasis.
Viruses cannot reproduce on their own, as they lack the machinery to do so. Instead, they rely on host cells to replicate. Once a virus enters a host cell, it takes over the cell's machinery and uses it to produce more viruses. This process can vary depending on the type of virus, but ultimately results in the production of multiple viral particles.
Yes, viruses can evolve through the process of natural selection. As they replicate and spread, mutations can occur, leading to variations in the viral population. These variations can give some viruses an advantage, allowing them to better infect and survive in their host. Over time, this can lead to the emergence of new strains or even new types of viruses.
The purpose of viruses is a topic of ongoing research and debate. Some scientists believe that viruses serve as a means of genetic exchange between different organisms, while others argue that they may play a role in regulating the population of host organisms. However, it is important to note that viruses also have the potential to cause harm and disease in their hosts.
Viruses are classified based on their genetic material, structure, and mode of replication. They are divided into different families, genera, and species, similar to the classification system used for living organisms. Currently, there are over 5,000 known species of viruses, and this number is constantly growing as new viruses are discovered and characterized.