What causes death and how can we prevent it?

[NoTime]

cite one form of life that exists on Earth that does NOT have nucleic acids as the ultimate cause of your repeated actions.

I did do just that
Perhaps you do not like my example, but that's an entirely different argument.

My biggest objection to your definition is the fact that life is the only thing that generally violates the law of entropy.
I would think that this feature would be required in the definition of life.

 

[arildno]

THis is not quite so. Pictures of people of the late 18th century at various ages (for example Benjamin Franklin, but the case is much more general) show them looking just about the way modern people look at those ages. The same is true for the busts of Roman emperors. The difference in modern demographics is not caused by differential aging but by differential death rates. Many more people died young, because of primitive, ineffective medicine, but those who survived aged just about as we do know. I am currently reading about Jefferson's last years; he died in his 80's and for the last fifteen years or so he suffered from hardened prostate and arthritis, something men still suffer, but he was generally active and went for horse rides nearly every day in his 70's.

About the only evolution that has taken place in humans^* since the ancient egyptians and sumerians is in resistance to disease. Descendents of Europeans, who were swept repeatedly by epidemics, have a good deal of immunity form being descendents of the survivors.


^*Of course there is the theory that Ashkenazi Jews evolved enhanced intelligence from being confined to occupations like money changing which required it.

Not really.
Please remember that those you are looking at (for example busts of emperors) are those that had access to the TOP-QUALITY food in their society. Also remember that compared to previous dietary regimes, the lower middle classes of the Western world today eat the food of emperors on a daily basis.

 

[Another God]

Using this definition viruses are living entities--types of cellular parasites.

The "viruses aren't living because they need cells to replicate" argument has never seemed sufficient to me. The same argument could be stated "Humans aren't living because they need the Earth to live off". Or any other number of obligate parasitic organisms can be defined as non-living because of this ever so simple definition.

The only reason that definition is applied to viruses is because they are so simple. Well, in relation to the ecosystem, a human is pretty damn simple too. Similarly a virus looks simple compared to a Eukaryotic cell from our perspective, but the chemistry involved is still incredibly incredibly incredibly sophisticed. Just because it is comparitively simple doesn't detract from the very repetitive and directed nature of its existence.

I think Viruses ARE an expression, an external packaging, of what life is. To be more specific, BIOLOGICAL life really is just replication of DNA and all of the other associations are just conveniences to allow genetic replication to occur in a more smooth, consistent or reliable manner.

(PS: I don't mean to define what "life is". What I mean to express is that this thing we see all around us really isn't so remarkable (I mean it is...but there's no magic involved..if you know what i mean) that there is something which makes it impossible to define. This 'life' which we are familiar with is just DNA replicating in various forms)

Hmmm, I guess in response to your original post Rabe: By my very statements above I would take your definition that step further. Life is the replication of DNA.

I could takr this concept a lot further, but I think I am just stealing all of Richard Dawkins' ideas now and making them sound like they are my own, so I will stop LOL.

Shane

 

[Another God]

Ahhhh the ramblings of a crazy person. Sorry for the non-sensical post. let me try to re-post myself with a sensible summary:

Simplicity doesn't change the function of life, and lifes function is consistent from the smallest to the largest: Replication of Nucleic Acids. The packaging of nucleic acids, and the causal relationship nucleic acids have with their packaging (proteins, lipds etc) need not be part of the definition for their only role is simply to facilitate the safe, reliable, consistent replication of nucleic acids. No matter how the DNA is packaged: In a protein case in a virus, in the cytoplasm of a prokaryote, or in the nucleus of a eukaryote no matter how that DNA is placed in a position where it can be copied (polymerase, denaturation and cooling in presence of nucleotides etc) then it acheives the goal.

Yes, a PCR machine is a short burst of life. LOL

And yes, upon reflection, this is certainly Richard DAwkins' theory. For more info, read the Selfish Gene.

Shane

 

[selfAdjoint]

Another God and Rade, isn't this just one of those endless semantic arguments? Of course the noun "Life" has big emotional connotiations for us, but just like "Species", "Race" and other big feeling nouns when you try to project its categories into real nature they blur irretrievably.

None of these concepts ar "well-defined" mathematically. People attempt well-definition, even to the point of setting up axioms, but then other people complain that those axioms fail to capture something that "everybody knows" fits into the category in question.

Even if Venter creates a synthetic bacterium, some people won't admit it's synthetic life till they see it done on cows and horses (or sheep, like Dolly; now THAT was something that convinced the public!).

 

[superweirdo]

lets get back to topic,(although we are talking about life, its not the in the sense I intended-philosophical)

someone in here earlier said that if you freeze us, our cells die, if that is true, then why are rich guys freezing their brains and bodies so if later they come up w/ a technology, they can bring them back?

 

[arildno]

Why do idiots do the things they do?
It is unanswerable, whether or not the idiot is rich or not.

 

[selfAdjoint]

Just another Venter link. This one is from 2003 but it has a very clear discussion of their plans and the difficulties. As far as I know they are still working on it.

http://www.carlzimmer.com/articles/2003/Venter2003.html

 

[Rade]

I did do just that Perhaps you do not like my example, but that's an entirely different argument.

But your computer = life example because computer does "repeated actions" makes clear why the statement "self generated action" must be part of any definition of life. That is, the computer does not assemble the information content of its software code, living entities do. Also, many non-living entities do repeated actions that decrease local entropy such as planets that repeat movement around sun instead of willy-nilly just moving randomly with large entropy.

My biggest objection to your definition is the fact that life is the only thing that generally violates the law of entropy.
I would think that this feature would be required in the definition of life.

Fair enough, as long as we are sure that no quantum machines can violate law of entropy--I have no knowledge of this one way or another. If not, then sure, we can modify my suggested definition of life as "life = self generated motion regulated by nucleic acids that results in local decrease of entropy over time"

 

[Rade]

Another God and Rade, isn't this just one of those endless semantic arguments? Of course the noun "Life" has big emotional connotations for us, but just like "Species", "Race" and other big feeling nouns when you try to project its categories into real nature they blur irretrievably. None of these concepts are "well-defined" mathematically. People attempt well-definition, even to the point of setting up axioms, but then other people complain that those axioms fail to capture something that "everybody knows" fits into the category in question.
Even if Venter creates a synthetic bacterium, some people won't admit it's synthetic life till they see it done on cows and horses (or sheep, like Dolly; now THAT was something that convinced the public!).

The science of Biology (study of life) IMO demands that some attempt be made to define the concept that is studied. This must be achieved not for communication, but for cognition, for before we can communicate the concept first must be before us a "living thing" that is the focus of our attention. I think it critical to offer definitions of the concept called life, then wait for them to be falsified, such is the way of science. Take the concept we call matter for example--it comes in many complex forms, yet it is defined as simple mathematical equation as M = E/c^2. IMO, someday a biological Einstein will derive the equation for the concept we call life.

 

[selfAdjoint]

The science of Biology (study of life) IMO demands that some attempt be made to define the concept that is studied. This must be achieved not for communication, but for cognition, for before we can communicate the concept first must be before us a "living thing" that is the focus of our attention. I think it critical to offer definitions of the concept called life, then wait for them to be falsified, such is the way of science. Take the concept we call matter for example--it comes in many complex forms, yet it is defined as simple mathematical equation as M = E/c^2. IMO, someday a biological Einstein will derive the equation for the concept we call life.

I disagree, all the scientists need to do science is a rough working definition. "What is life" is to biologists as "What is the wave function" is to quantum physicsts; something outsiders obsess about but only a few professionals ever bother their heads about.

 

[superweirdo]

After you guys are done discussing about the definition of life, could you explain to me why can't a doctor freeze the body of a person who just died and then replace his brain and heart?(depends on how he died). B/c freezing cells don't kill them, it hybernates them.

 

[selfAdjoint]

After you guys are done discussing about the definition of life, could you explain to me why can't a doctor freeze the body of a person who just died and then replace his brain and heart?(depends on how he died). B/c freezing cells don't kill them, it hybernates them.

Water expands when it freezes, unlike nearly all other materials. This property is very important for life, but it means that freezing cells runs into the problem of ice crystals bursting the delicate structures in cells. There has been a LOT of research for many decades in trying to work around this problem, but such successes as have been announced are very small scale. Fact is when you freeze living tissue and then thaw it again what you get is dead tissue.

 

[arildno]

A more viable option would be the one some bugs use:
Effectively, they empty their cells of water, and fill them with a sort of "freezing" liquid that remains in fluid state at much lower temperature.
Their metabolism and signs of life stop, even though their inner machinery is unharmed.

Once more favourable external conditions are present, they "de-freeze", and wake to life again

 

[superweirdo]

Wait a sec, is there any research going on where they are trying to put freezing liquid in our body and see what happens?(they would need some suicidal volunteer for that though). I believe that the people who want to suicide should contribute to such experiments.(not if they can be stopped but sometimes, it is too much)

 

[Moonbear]

Wait a sec, is there any research going on where they are trying to put freezing liquid in our body and see what happens?(they would need some suicidal volunteer for that though). I believe that the people who want to suicide should contribute to such experiments.(not if they can be stopped but sometimes, it is too much)

We don't need to try to freeze whole bodies to know that cells burst when frozen. It's hard enough cryopreserving single cells and small pieces of tissue without this sort of damage occurring, and doing it requires infiltrating the tissue with substances that have "antifreeze" properties, like glycerol.

But, since we've answered your question multiple times over, and the remainder of discussion has diverged off into philosophy, I'm going to close this thread here.