Viruses: alive or not?

reply to post by Lazarus Short


I bet that kid who got hit by lightning when he left the school function a while back didn't have to worry about infections from existing bacteria or viruses. What were his last words as he left? "What could happen, like I am going to get struck by lightning" or something like that.: Now he's a shaman whether he likes it or not.

Originally posted by PatriotAct
Of course most biologist claim they're not, but here is my reasoning to why they are. Their classifications as to why they're not living, such as the viruses' ability to sustain homeostasis, that's where I think the definition falls apart. In order for you, a human, to sustain homeostasis you must be in an environment where the body can do so. That is of course the earth. Without our environment none of us could undergo homeostasis. The same applies to viruses. Alone they're dormant, but in the right environment, such as the human body, they too can engage in homeostasis. So basically, virii and humans are one in the same. Furthermore, I would wager humans are a virus on the earth.

Homeostasis is equilibrium as maintained by physiological processes, which viruses lack, hence your argument contradicts itself.

reply to post by Ayana


I tend to just think of virus' as being 'alive' but when dormant are in a true state of suspended animation.They most certainly aren't dead at that point. Upon coming into contact with a usable host they re-energize to attack and take over the host's cells.

There is no all encompassing criteria for "living" vs "not living".
It's really quite complex, I think Carl Sagan explained it best in one of his books.

Anyways, in the end, the determination of what is "life" can vary depending on who you ask. That would lead me to conclude there is a degree of subjectivity and that it is quite relative depending on how you perceive it.

Remaining open minded yet analytic seems to be a good strategy for approaching the subject.
Good question though, always nice to see people asking "what is life?".

Check this quick Google result I came up with:

Despite the abundance of life surrounding us, there is currently no generally accepted definition of life. In the 1970s, Carl Sagan, astronomer and exobiologist, attempted to define life through five categories of definitions. However, problems arise in the form of counter-examples of objects we would not consider “alive,” but fulfill the requirements of the definition.

5 Criteria for Life and Problems...

More philosophical musing for those interested to enjoy it:

"Viruses straddle the definition of life. They lie somewhere between supra molecular complexes and very simple biological entities. Viruses contain some of the structures and exhibit some of the activities that are common to organic life, but they are missing many of the others. In general, viruses are entirely composed of a single strand of genetic information encased within a protein capsule. Viruses lack most of the internal structure and machinery which characterize 'life', including the biosynthetic machinery that is necessary for reproduction. In order for a virus to replicate it must infect a suitable host cell".

Carleton.edu resources

Although there is no definitive resolution to the question of whether viruses can be considered living entities, their ability to pass on genetic information to future generations makes them major players in an evolutionary sense.

So really the best answer is that we don't have a real solid answer. Although this may leave things "up in the air" so to speak, it will keep us "on our toes", and we will remain in a state of questioning. I see a lot to gain from this process.

reply to post by Ayana

But on the other hand, viruses could do none of the criteria for living without a host to bring it about.

I think this is the ultimate line to consider when discussing whether or not viruses are alive.

However - the points you mention are very good ones.

I do it often, but for good reason; I will evoke the Red Queen: The Red Queen Hypothesis sets the groundwork for a new understanding of life, in general. If viruses didn't exist, we would all reproduce asexually, and multi-celled organisms may never have evolved.

Viruses have evolved alongside life - however it was they first came about - and have been one of the primary factors influencing natural selection - even more powerful than the environment in many cases.

I no longer think it's completely accurate to think of life as being separate from viruses. Not that viruses are alive, per se, but that it is an anterior companion to life. Much how the Earth's geological functions are largely influenced (when not directly caused) by the moon - not entirely separate from Earth, but not really Earth, either. The two together, however, form a system that has been conducive to life as we know it.

Wiki on Red Queen Hypothesis: en.wikipedia.org...

Other links of interest:

bevenjamieson.com...

www.indiana.edu...

www.indiana.edu...&recomb.html - examines real-world data

www.kurzweilai.net...

www.britannica.com...

www.wellcome.ac.uk...

When the bacteria were unable to adapt themselves, the rate of virus evolution slowed down to almost half that seen when the two species were allowed to evolve in tandem. What's more, the team found there was much less genetic variation in the resulting virus populations than those that co-evolved with the bacteria under Red Queen evolution.

"Together, our findings suggest that it is the interactions between species that are the main drivers of evolution. And by causing rapid divergence, they could even lead to speciation itself," said Dr Brockhurst.

discovermagazine.com...

The bacteria seem to gain nothing from this transaction. In fact, if this is proto-sex, it’s proto-bad-sex, because neither bacterium can be described as consenting. The plasmid contains the quintessential selfish gene, a bit of DNA whose only mission is to reproduce itself, thus driving the plasmid to distribute as many copies of itself to as many hosts as possible. In the process, bits of the original bacterium’s genome occasionally cling to the plasmid like foxtails on a dog’s coat and find themselves in the new host. Eventually, explains Rose, some hosts begin to use and benefit from the inadvertent gift of another individual’s DNA.

Rose and Hickey have gone on to propose that selfish DNA could account for a primitive form of sex that’s closer to sex as we now know it. In some early single-celled organisms, they theorize, selfish DNA didn’t merely cause a bridge to form so that it could travel from one individual to another--it impelled the two organisms to actually fuse, in a primitive anticipation of what sperm and egg do during fertilization. This parasitic DNA could then spread contagiously until the whole population was committed to sex.

This parasitic gene theory has also been proposed to explain the origin of males. While I'm sure that garners a bit of a laugh - an asexual or hermaphrodite population would be driven to extinction by a the 'parasitic' genetic material now contained in the Y-chromosome (a very small and stunted chromosome by comparison to all others). The surviving adaptation was the ejection of that bit of genetic material into its own chromosome.

Earlier theorists had assumed that sex was advantageous in the long run because it produced variability in gross features like size and shape, thus equipping species to adapt and roll with the inevitable environmental punches. If that were the case, then sexual organisms ought to turn up in harsh areas on the frontiers of an organism’s habitat, and clones ought to live only in cushy environments. In fact, nearly the opposite is true: clones tend to predominate in frontier settings, while sexual organisms fill the niches in environmentally stable zones

Which goes along with my opinion that viruses shouldn't really be considered apart from their hosts. Even if they're not alive.

This is a new subject for me, haven't got much to add, but I liked the read a lot!

I've always considered viruses as little machines with no real significance other than reproduction... Ahh guess that might be a solid definition for every organism. Anyway, when I try to visualise a virus, I instinctively come up with a sort of metallic, mechanical design, lifeless. And when I think of cells, or bacteria, I get an image of a moist clump of jelly, like the amoeba. Distinctly alive. I guess this might be a slightly twisted view embedded by schoolbooks...

Too bad researching this stuff independently is so damn hard, don't know where to start. I got very interested when I saw a pic of a T4 virus. Such a ridiculously beatiful design, it almost seems like it was intentionally manufactured.

Originally posted by rickymouse
reply to post by Lazarus Short

 

I bet that kid who got hit by lightning when he left the school function a while back didn't have to worry about infections from existing bacteria or viruses.

What were his last words as he left? "What could happen, like I am going to get struck by lightning" or something like that.

: Now he's a shaman whether he likes it or not.

You seem to be hung up on the subject...zap!

reply to post by Ayana


Good O/P- It's good to probe these areas, sometimes they get skirted around and brushed under the carpet...

Here's my input: firstly, define 'living'.

I urge everybody to watch this

Martin Hanczyc: What is 'life'?

Viruses are alive. just because science doesn't classify them as living doesn't mean they aren't. I think Science should look at their definition of life and make some adjustments.

The earth is alive, It's crust full of life. Humans are made up of millions of cells, many of which do not have our DNA and they still call us alive. We are even part of a living planet.

Originally posted by rickymouse
Viruses are alive. just because science doesn't classify them as living doesn't mean they aren't. I think Science should look at their definition of life and make some adjustments.

The earth is alive, It's crust full of life. Humans are made up of millions of cells, many of which do not have our DNA and they still call us alive. We are even part of a living planet.

Alive/not alive is a false dichotomy; there are merely chemical reactions, albeit some more complex than others.

I always wondered about viruses and white cells about one thing. Do they have some kind of sense? There's this gif I saw of a virus that makes it look like a virus is running away from a big ass wobbly white cell. It really appears like both of them "know" that there is enemy present. It could be just an appareance but is there a possibility that they have some unknown kind of sensing cabability?

Originally posted by PsykoOps
I always wondered about viruses and white cells about one thing. Do they have some kind of sense? There's this gif I saw of a virus that makes it look like a virus is running away from a big ass wobbly white cell. It really appears like both of them "know" that there is enemy present. It could be just an appareance but is there a possibility that they have some unknown kind of sensing cabability?

Qurom sensing and protein chemical communication is how microbes interact.

From what I understand is that is how same or similar cells communicate? So are white cells somehow equipped to sense viruses through this method and visa versa?

Originally posted by PsykoOps
From what I understand is that is how same or similar cells communicate? So are white cells somehow equipped to sense viruses through this method and visa versa?

Yes, they're evolved to do so.

I saw a good documentary on this a while back, let me see if I can find it

Edit: found it, see link

www.bbc.co.uk...

reply to post by Ayana


One thing you mentioned towards the end of your second op "viruses could do none of the criteria for living without a host to bring it about" ... In a similar sense couldnt us humans not do anything without the "hosts" which bring us about?

reply to post by 1nquisitive


Thx, I'm going to have to see this sometime. It wont let me watch it from bbc

Found the clip I was talking about as YT video. Science is effin awesome!



Also just noticed it's bacteria and not a virus. This is not my field at all

reply to post by Ayana


No true knowledge concerning Biology, may I therefore ask 1 question. I read how one teaspoon of seawater could carry up to 14 million viruses. These are found to carry Horizontal Genes.
At sea is it possible the virus helps keep certain bacteria alive by delivering such horizontal genes. Assuming the bacteria can stop such from multiplying - as it does whe we are infected.. At sea the virus has a job.
If seabirds, ducks etc. collect such virus, then fly inland and dry off. Is it possible that the Virus is then delivered to wrong address, hence infections ???
After all we can swim in the sea and emerge not infected.
Curious because I do keep many Fish (as a Hobby).

Originally posted by rickymouse
Viruses are alive. just because science doesn't classify them as living doesn't mean they aren't. I think Science should look at their definition of life and make some adjustments.

The earth is alive, It's crust full of life. Humans are made up of millions of cells, many of which do not have our DNA and they still call us alive. We are even part of a living planet.

Viruses don't really DO anything by themselves. They don't respire, they don't make proteins, they don't reproduce, they don't excrete, they don't respond to stimuli, they just sit there. Without hijacking the organelles of a cell, they are a package of information, no more alive than the contents of my hard drive.

Originally posted by Bedlam

Originally posted by rickymouse
Viruses are alive. just because science doesn't classify them as living doesn't mean they aren't. I think Science should look at their definition of life and make some adjustments.

The earth is alive, It's crust full of life. Humans are made up of millions of cells, many of which do not have our DNA and they still call us alive. We are even part of a living planet.

Viruses don't really DO anything by themselves. They don't respire, they don't make proteins, they don't reproduce, they don't excrete, they don't respond to stimuli, they just sit there. Without hijacking the organelles of a cell, they are a package of information, no more alive than the contents of my hard drive.

What causes them to hijack organelles of a cell?