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Living things... - The highs and lows of KuteLuvr

About Living things...

Previous Entry Living things... Apr. 27th, 2005 @ 10:41 am Next Entry
For some strange reason, I find myself thinking about what constitutes "life" and "living". I'm not talking about the experience of living, but rather the technical, scientific definition of life.

For example, at what point do we consider something to be "living"? Put in it's absolute, fundamental way, where does something change from being just "matter" to being "living matter"?

We consider ourselves (and whole lot of other things) to be "alive"... where does that begin, exactly? We are living beings... our organs are considered to be alive... our cells are alive. The debate is still on about viruses, but I think a minor majority of science considers the virus to be a form of life.

So, where does this life begin? If a cell is alive, we might consider the mitochondria in it to be alive, right? Certainly, life processes and functions are performed by those intra-cellular blobs... what about the nucleus? Is DNA alive? Does that then imply that the molecules DNA as a whole is composed of are alive? If a molecule by itself can be alive (not saying that it can, but if), then why isn't that brick over there alive? Why isn't the sun alive? (it's certainly doing things on it's own).

Where exactly does the line between living and non-living live?
Current Mood: curiouscurious
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Date:April 27th, 2005 06:58 pm (UTC)
My flip answer is that a life form is a system that locally reduces entropy. While there are non-biological processes that can polarize a system into higher and lower entropy zones, I don't think there is any that can keep its entropy low relative to surroundings as well as what we call life forms.

Bucky fuller used the term pattern integrity to describe a thing that was more than the sum of its parts. That is, there was some synergetic process that couldn't be predicted from examination of the component pieces. He considered a living being to be something akin to a waveform passing through the medium of matter. Since most of the atoms in our body are replaced on a regular basis, it's a good point to consider.

I think viri are considered to be life forms because they can evolve to adapt to different environments. I'm not sure about prions though. Mitochondria are thought originally to have been independent organisms that invaded eukaryotic cells and evolved a symbiotic relationship. They have their own DNA, which is kind of bizarre. Mitochondrial DNA also evolves, and you can trace matrilinial family lines using it. Seems alive to me, but I doubt it could survive on its own anymore.

Something to think about: How much of you is you and how much is something else? You have several pounds of bacteria living in your intestines. By any reasonable estimate there are more bacterial cells colonizing your gut than there are cells that make up your body. Who's body is it anyway? Where do you stop, and where does not-you begin?
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Date:April 27th, 2005 09:10 pm (UTC)
as a trekkie freak, I too have wondered this question. is Leitenent Commander Data alive or is he merely a clever interactive robot?
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Date:April 28th, 2005 12:15 am (UTC)
There is a five-fold test from Biology ("life" has to meet all five):

1. has mass
2. takes up space
3. exhibits irritability
4. reproduces itself
5. I forgot this one.
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Date:April 28th, 2005 12:34 am (UTC)
life begins when you get tivo.

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