
New Giant Viruses Further Blur the Definition of Life - IntronExon
https://www.quantamagazine.org/new-giant-viruses-further-blur-the-definition-of-life-20180305/
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mgeorgoulo
I bet every biology student has struggled with the introductory "what is life"
chapter, full of conflicting definitions.

It is so difficult to define life because there is nothing to be defined.
There are complex stuff and simple stuff. We tend to call things that exhibit
a certain degree of complexity "alive", but that's just a word.

Can't remember who wrote the perfect definition of Biology: "The study of
complex things". There's a great deal of wisdom in that.

~~~
tome
> Can't remember who wrote the perfect definition of Biology: "The study of
> complex things". There's a great deal of wisdom in that.

Human society is complex, but it would not normally be considered biology.

~~~
pc86
Society isn't one thing, so perhaps a better definition would be "Biology is
the study of a complex thing?" Regardless, pedantry.

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Latty
To continue the pedantry - what makes society not one thing, but a human one
thing? That seems like a matter of perspective.

~~~
pluma
I was going to joke it's about medium sized things but size is not a
reasonable distinction (neither absolute size nor number of "parts") and you
quickly run into the problem how organisations (i.e. groups of humans acting
together) or machines (e.g. a car) are fundamentally different.

I guess the definition really is pretty fuzzy and arbitrary. It's "obvious"
why a bunny is biology and a car or company is not, but it's not quite so
obvious why a virus or an android isn't.

Heck, xenobiology seems to be inherently problematic because alien life would
defy all classification. Imagine the "xenomorph" from the Alien universe.
Would that be considered a reptile? Is it even a vertebrate? What animal
rights legislation would apply to it if any? Would a "grey" count as a person?
We like to justify these laws with biological categories but what do we do
when faced with situations where the categories break down?

EDIT: Is an artificial, viable sheep-human hybrid an animal or a human?

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Latty
> We like to justify these laws with biological categories but what do we do
> when faced with situations where the categories break down?

Change them to suit the world as we understand it.

The reality is that classifications as strict rules are a fantasy we choose to
believe in, but at the end of the day, classifications are descriptions, and
so we have to mutate them to help us describe things as best we can.

The reality is we work to the level of detail and accuracy we need. Rigidity
in labels and classification is probably a sign of a lack of understanding,
because almost everything ends up being broken down more at some point, and
exceptions are found that break the rules.

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antiviral
What if we could use the notion of entropy in a definition of life?

Living things use energy to prevent entropy (decay?) while they are alive.

On the other hand, natural, non-living processes do no such thing, and
increase entropy as governed by the law of thermodynamics.

We could also use criteria such as growth, reaction to stimuli, and
reproduction. However, crystalline structures also grow and chemical processes
may produce more of a certain molecule. All of those seek some energy
minimizing equilibrium without any mitigating mechanisms.

~~~
snowwrestler
You can't beat entropy, or prevent it. All you can do is change its
distribution.

So, one way to look at living things is that each one is a local depression in
entropy. But because you can't make something from nothing, each living thing
has to broadly increase entropy in their environment, in order to decrease it
locally.

Thus if we envision entropy as a surface, a living thing is not a depression
from a flat plane, but rather more like a hill with a steep depression in the
middle.

But again, since you can't have something from nothing, life can't arise from
an environment of maximum entropy. In order for life to come into being, local
entropy must be low enough for a hill to develop. This is where the entropic
definition gets into trouble, because the local low-entropy environment around
here is provided by the sun. And if you define life as any local depression of
entropy, then it raises the question of whether the sun is alive.

Maybe it's better to think of life as a system, not an attribute. To use an
analogy, you wouldn't look at a single wave in a rapid in isolation, and
wonder what it is. Without the broader context of the river, you'll never
understand how the wave came to be there. If every living thing is a like a
ripple in the local entropic surface, we can point to individuals, but could
only really understand them if we consider the whole picture of the solar
system.

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sebazzz
I never understand why viruses are not life. Bacteria are life because they
are essentially a single-cell organism and act like any cell in our body: they
consume energy and produce waste. Viruses may not be a cell, but they can be
damaged, they die, and they appear to be more than a simple chemical process.

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ohf
Viruses are more like robots. They don't respond to stimuli. They just, do.

The definition of "life" comes down to splitting hairs. We don't consider
something "alive" if its behavior doesn't change when its environment does.

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felipemnoa
>>Viruses are more like robots.

A virus is just a computer program that needs a Von Neumann machine (CPU) to
run on. Following this analogy we could define alive by saying that the
combination of a program and a Von Neumann machine makes the entity alive.

~~~
dmurray
Except that they really do have a physical manifestation (from the article,
the cylindrical tail, the polyhedral box containing the genes, the fibrils on
the outside). In some way they are closer to being the USB stick containing
the computer program, that can reproduce onto other USB sticks but needs a
host computer to do so.

~~~
pluma
Everything[0] has a physical manifestation. A computer program has a physical
manifestation on its storage medium.

[0]: Let's not argue about whether it makes sense to say that abstract
concepts also have a physical manifestation. Programs are concrete expressions
encoded on a physical medium (whether using magnets, electrical charges or
even the position of mechanical switches).

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skissane
Trying to define "life" is one of the central questions of the philosophy of
biology. And the positions one takes in the philosophy of biology are
inevitably going to be influenced by one's metaphysical positions regarding
the problem of universals. A nominalist, a Aristotelian realist, a Platonist
(etc.), are all going to approach the question "what is life?" differently.

Sometimes when people discuss this topic, they assume a certain approach to
metaphysics without making that assumption explicit (indeed, they may not be
aware that there are genuine alternatives to their personal metaphysical
positions.)

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nonbel
>"Trying to define "life" is one of the central questions of the philosophy of
biology."

If this is true then "philosophy of biology" is a likely a total waste of
time. It is obvious that life vs non-life is an artificial categorization that
humans use because it is useful to them.

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skissane
Your response presumes a particular philosophical position. When you call life
"an artificial categorization that humans use because it is useful to them",
you are espousing the nominalist solution to the problem of the universals,
and applying that to biology. Even while attacking the philosophy of biology
you are actually engaging in it.

Nominalism may be "obvious" to you, but it isn't obvious to everyone. Just
because someone thinks something is "obvious" it does not automatically follow
that it is true. Have you given serious thought to nominalism's alternatives,
such as moderate realism (Aristotelian, Thomistic or Scotistic); or Platonism?

~~~
nonbel
There isn't any deeper philosophy behind what I said, it has nothing to do
with how things "really are".

Just go categorize some stuff and see what happens. Is a bottle cap a "coin"?
In some cases, sure that could be. In others, not at all.

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nyc111
I consider legal entities such as corporations to be living organisms. So I
don't agree that life is limited to organisms with a visible (biological)
body.

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WJW
In fact, corporations display many of the characteristics we typically
associate with AI: perfect recall due to record keeping, ability to pay
attention to many things at once, in theory immortal as long as it can keep up
funding itself, can do projects that surpass the ability of any normal human
to comprehend by itself, etc.

It's a bit slower than we regularly imagine computer-based AI to be, of course
:)

~~~
thaumasiotes
> perfect recall due to record keeping

I'm pretty confident there are not now, and never have been, any corporations
with this characteristic.

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meri_dian
Here's a controversial view, but any good comments section needs a few of
them:

Viruses are no more "life" than bacteria are "life" or amoeba are "life" or
ants are "life" or mice are "life" or humans are "life"... We're all just
chemical machines, nothing more nothing less.

Giving the word 'life' some special significance is misleading and confusing.
In order to not confuse ourselves we should be talking about functions and
descriptions of those functions as implemented among chemical machines.

Do viruses reproduce? Yes, by hijacking cellular machinery. Do bacteria
reproduce? Yes, by cloning themselves. ...

This sort of thinking about the world allows us to stay close to reality
without abstract and ultimately meaningless distractions like 'life'. Heaving
the burden of abstraction onto 'reproduce' is still dangerous, but much less
so than allowing 'life' to lurk as an abstract category in our minds.

~~~
Synaesthesia
The problem with that analogy IMO is that machines can be comprehended by
humans, whereas even the most primitive forms of life are more sophisticated
than anything human created.

Reproduction is an astonishing feat in itself - if only we could create a
machine which could reproduce, but it's not so simple!

~~~
cobbzilla
Reproduction is easy, and was done in software, on the Internet, in 1988 [1].
There is a lot more to life than mere replication, for example homeostasis.
The Morris Worm did not make any efforts to maintain homeostasis, and thus
became extinct relatively quickly.

[1]
[https://en.wikipedia.org/wiki/Morris_worm](https://en.wikipedia.org/wiki/Morris_worm)

~~~
Synaesthesia
A physical man made object that can reproduce itself though - that is an
incredible challenge.

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XorNot
1 micron is amazingly large. 300nm is about the threshold to resolve a
particle under light microscopy, so these things would just be there - you
could use a pipette and push them around.

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tensor_rank_0
anyone hear the theory that cytomegalovirus is a fragment of a gigantic
prehistoric virus? a nurse friend heard about the theory in his medical
microbiology class but I haven't been able to find much online.

~~~
emerged
d-d-dino virus? non-life finds a way.

Fascinating if true.

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novia
relevant radiolab episode here:
[http://www.radiolab.org/story/shrink/](http://www.radiolab.org/story/shrink/)

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ozy
My personal definition of life: self-replication with unlimited heredity.

self-replication: something can make a copy of itself.

unlimited heredity: when "information" is added, it is copied along, even if
it does not contribute directly to the replication process itself.

Implied in the definition is variation. And in the bigger view, that all
replicators are under pressure to do so well, or be outcompeted on resource
usage etc., and disappear.

While a virus depends on a rich and active environment to work, they clearly
fall into that definition.

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tehwalrus
This definition includes computer viruses. Did you mean to?

~~~
ozy
Sortof. But with a few caveats. 1) most computer viruses don't randomly vary,
and thus don't have a learning effect, miss unlimited heredity. 2) they are
not physical life, so the relevance is not the same as their chemical
counterparts.

~~~
zaarn
I wonder what would happen if we taught a computer virus to modify itself
without restriction.

Of course, most of those viruses would probably just be rendered inert,
printing a lot of segfaults into the kernel console.

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kleer001
Nature is not constrained by human imagination.

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Isamu
Wasn't it always taught that an active metabolism separates living from
nonliving?

This brings up other questions though about how complex a virus can be. And if
they can be arbitrarily complex, will we rethink our definitions?

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jimmahoney
"Life. Don't talk to me about life." \- Marvin.

[http://hitchhikers.wikia.com/wiki/Marvin](http://hitchhikers.wikia.com/wiki/Marvin)

