Are Viruses alive?
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epic off-season debating
Viruses are Alive:
This is because recent evidence states that they have evolved from cells and should be considered life.
Milliken 2015 explains that “It suggests that viruses were not simply shed genetic material of cells, but shared unique properties with cells (and thus were living) and eventually evolved as separate entities. “We are now able to build truly universal trees of life,” says Caetano-Anolles, “that describe the origin and diversification of organisms and viruses.”” (https://www.popsci.com/new-evidence-that-viruses-are-alive)
Furthermore, MacDonald 2015 reveals that “Now a study by researchers in the US has managed to complete the first viral tree of life, and it suggests that not only are viruses alive, they're also really, really old, and they share a long evolutionary history with cells. "Viruses now merit a place in the tree of life," lead researcher Gustavo Caetano-Anollés said in a press release. "Obviously, there is much more to viruses than we once thought."” (https://www.sciencealert.com/viruses-are-alive-and-they-re-older-than-modern-cells-new-study-suggests)
He furthers by saying that because Viruses originated from ancient cells, “Of course, this doesn't mean that viruses suddenly fit neatly into our definition of life. But the researchers suggest that the evidence is strong enough that we may simply need to expand our understanding of what it means to be 'alive'.”
KhanAcademy writes that viruses only fail in a test of life in 2 categories, something that can easily be made up with a broader definition of life. (https://www.khanacademy.org/test-prep/mcat/cells/viruses/a/are-viruses-dead-or-alive)
Because viruses hold a tight evolutionary connection with cells, already being called life by multiple scientists, and can fit the definition by broadening what we define as life, viruses are alive.
Evolutionary Biologist LUIS P. VILLARREAL: most evolutionary biologists hold that because viruses are not alive, they are unworthy of serious consideration when trying to understand evolution. Due to the fact that genetic mutations within cannot happen without the complete aid of a host cell. Their genetic material is just wrapped in proteins and isn't subject to evolution. (https://www.researchgate.net/profile/Luis_Villarreal3/publication/8131916_Are_Viruses_Alive/links/0c9605212714edf204000000/Are-Viruses-Alive.pdf)
According to Merriam Webster evolution is defined as: "descent with modification from preexisting species : cumulative inherited change in a population of organisms through time leading to the appearance of new forms : the process by which new species or populations of living things develop from preexisting forms through successive generations." Viruses don't follow this definition, although genetic material does change successive generations have little to do with this. New forms of viruses are not created by inherited genetics.
Your second argument is based off of argumentum ad verecundiam, in which completing a viral tree of life does not add anything to the argument of whether viruses are alive. Using the same press release you cited, protein folds can be applicable to ribosomes and the nucleus. However they are not considered alive even though they carry proteins that are folded "giving them their complex, three-dimensional shapes." (https://www.sciencedaily.com/releases/2015/09/150925142658.htm)
From the same press release: "This tells you that you can build a tree of life, because you've found a multitude of features in viruses that have all the properties that cells have," This statement does not seem to make much sense to me. The same can be said about a lot of different things. Defining something based off of the properties that it shares with another thing that relates to it.
First, I will be stating the burden of proof that my opponent provides in order to win this round, then explaining why my argument fits into the framework of this debate, and ending on a refutation of his points.
First, my opponent concedes that life should be based on the ability for mutations, as states when they say that "Evolutionary Biologist LUIS P. VILLARREAL: most evolutionary biologists hold that because viruses are not alive, they are unworthy of serious consideration when trying to understand evolution. Due to the fact that genetic mutations within cannot happen without the complete aid of a host cell. Their genetic material is just wrapped in proteins and isn't subject to evolution."
- I'd like to note that this source is only pertaining to understanding evolution, not in determining whether viruses are alive or not, but for the purposes of this debate, I will accept this framework.
- My opponent then provides this definition and this reasoning to mutation: "According to Merriam Webster evolution is defined as: "descent with modification from preexisting species : cumulative inherited change in a population of organisms through time leading to the appearance of new forms : the process by which new species or populations of living things develop from preexisting forms through successive generations." Viruses don't follow this definition, although genetic material does change successive generations have little to do with this. New forms of viruses are not created by inherited genetics.
- In short, if I am able to prove that new forms of viruses are created by inherited genetics, viruses should be considered alive.
Now, I will be going over why viruses fit this definition of life.
- If "inherited genetic" mutations are defined as "changes that divert from a base set of genetics", viruses are considered life. For example, the influenza virus has multiple subtypes and continue to rapidly change its genetics, However, new subtypes of the flu are called subtypes and not a completely new virus because the genetic information between subtypes are similar and they all come from a single influenza virus.
Finally, let's go over some of their rebuttals.
- They start off by saying that a viral tree of life adds nothing to this debate, however, they fail to see other examples. For example, in my first source (Milliken 2015), "But within the last decade, developments in virology have started to reveal more and more that viruses might in fact be alive. One was the discovery of mimiviruses, giant viruses with large genomic libraries that are even bigger than some bacteria. To put this in perspective, some viruses, like the Ebola virus, have as few as seven genes. Some of these giants have genes for the proteins that are required for translation—those readers of DNA and RNA that in turn build new viruses. This throws the lack of translational machinery argument for classifying them as nonliving on its head."
- They also try to discredit the protein fold proof, but, again, Milliken 2015 tells us that "And now for the numbers. Caetano-Anolles and Nasir analyzed the protein folds of 5,080 organisms—3,460 viruses and 1,620 cells from other organisms representing every branch of the tree of life. What they found was huge: 442 protein folds were shared between cells and viruses along with 66 folds that were unique to viruses. What this indicates then, is a branching of some kind. It suggests that viruses were not simply shed genetic material of cells, but shared unique properties with cells (and thus were living) and eventually evolved as separate entities. “We are now able to build truly universal trees of life,” says Caetano-Anolles, “that describe the origin and diversification of organisms and viruses.” These findings provide some of the strongest evidence yet that viruses are indeed living. “The mere fact of the existence of a universal biology unifying viruses and cells now justifies the construction of a Tree of Life that embraces viruses side by side with cells.” says Caetano-Anolles. The interesting thing about these results is that they indicate that viruses must have diversified from ancient cells by a process called reductive evolution, where organisms simplify instead of becoming more complex. Viruses were likely “more cellular in nature and existed in the form of primitive cells,” explains Nasir. The ancient cells that these primordial viruses resided in were those of the last universal common ancestor that preceded diversified life about 2.45 billion years ago.
In conclusion, because viruses fit the definition of life that my opponent has provided, as well as the fact that my opponent's rebuttal to my first speech doesn't have much substance, I urge you to believe that viruses should be considered as life.
Think I’d be up for that, though I may want to challenge the basic definition of life if this is it.
Ok, I might put up the debate on the open debates and you can accept it if you like my definitions, so I don't flood these guys' debate comments section.
If that is living, then there would be a lot more excluded from this definition than I'd previously expected. Case-in-point: spores. Bacterial and fungal spores are about as passive as it gets, built to last and survive harsh environments and little else. They aren't battling the environment, they simply withstand what the environment can dish out. The same holds true for viruses. I'd still say spores are living, despite their passivity. Similarly, I'd say that any organism that requires another organism's metabolism to perform its own basic processes is not autonomous.
It is really cool. If you look up huge viruses like the Mimivirus or Pandoravirus and check out their virophages, you'll see some really awesome pictures.
I didn't put it in my 5 to be alive, but it is in the definition of life, because life is actually just a property of organic compounds when they are no longer passive and are actively recruited to fight for the system's survival. Living is an active battling of the environment and the characteristics necessary to have that battle are what define life.
Not having this autonomous characteristic makes it like a passive organic compound whose activity is at the direction of something autonomously living.
I didn't know about parasites for viruses, that's fucking cool, and it does speak to viruses' ability to behave like life.
There are viruses that have all the tools required for their metabolism within their capsids and are themselves parasitized by other viruses, so in a sense, yes. I will note, however, that the definitions do not include an "autonomous" requirement.
Are there viruses that autonomously metabolize?
To make a long story short, I find that it's human-centric. The history of how we define life starts with how we define what makes us alive, and then slowly expands as discoveries of bacteria that didn't quite fit that definition began. Some of those defining characteristics don't even fit some bacteria very well, particularly those that are obligate parasites. Honestly, though, I just have trouble understanding why this set of traits are required for life, particularly the first and third. What is so special about cellular organization? What is it about having a membrane that makes one alive? I can only understand that through the view that we are defining life as similar to ourselves. The same goes for homeostasis, which is required for the survival of membrane-bound organisms, but not for viruses. While I understand these choices as narrowing down what life is, I can only justify them if I'm deliberately trying to exclude that which does not fit neatly into these categories, though I can also argue that some viruses fit all 5.
So this topic was actually the essay topic for our district's benchmark assessment, and the curriculum explicitly states viruses cannot be living because they've no cellular organization, and since it's an all or nothing concept, students basically have to argue one way.
That being said, the arguments for viruses essentially behaving identically to life and perhaps being a precursor to it are compelling, but what is your major contention with the "need 5 to be alive" mantra?
Yep, I remember it well.
You guys should debate this, but I'm wondering if either of you were taught in biology the old rule "You need all 5 to be alive" the five characteristics being:
1. have cellular organization
2. able to inherit traits
3. maintain homeostasis
I noticed, doesn’t seem like it was much of a debate, though. Be happy to debate you on it, though. I’d argue they’re alive.
Btw, no cells, no life...done.
Let me know when this is finished and I’ll post a vote.