PDA

View Full Version : Why do we age?


freddy
October 5th 04, 05:42 PM
Why do we age?

My niece asked me this the other day. I said that I seemed to recall that it
is due to damage caused by free radicals.

Is this correct?

John HUDSON
October 5th 04, 08:37 PM
On Tue, 05 Oct 2004 16:42:46 GMT, "freddy" > wrote:

>Why do we age?
>
>My niece asked me this the other day. I said that I seemed to recall that it
>is due to damage caused by free radicals.
>
>Is this correct?

No of course not freddy, it's all to do with the passing of time which
is quite relentless and out of our control.

Now the process of aging as the result of time, well....... that's
quite a different matter and a process culminating in decomposition,
which is something you should not really be discussing with a
delightfully naive niece!! ;o)

David Cohen
October 5th 04, 08:45 PM
"freddy" > wrote
> Why do we age?

God designed us that way.
The immutable passage of time.
Evolutionary design.
Demonic possession.
Telomeric degradation.
Something else.
Add your own.
Pick one.
Don't expect that you are correct.

> My niece asked me this the other day. I said that I seemed to recall that
> it
> is due to damage caused by free radicals.

Not only are they free, they run for President sometimes.

> Is this correct?

Is it safe?

David

Mistress Krista
October 5th 04, 09:11 PM
"freddy" > wrote in message
...
> Why do we age?
>
> My niece asked me this the other day. I said that I seemed to recall that
> it
> is due to damage caused by free radicals.
>
> Is this correct?
>


In part. However, there are complex mechanisms that decide when it's time
for the cell to check out. You might like a little book called A Means to
an End: The Biological Basis of Aging and Death, by William Clark.


Krista

--
http://www.stumptuous.com/weights.html
http://www.trans-health.com
mistresskrista at stumptuous dot com

freddy
October 5th 04, 10:19 PM
"Mistress Krista" > wrote in message
...
>
> "freddy" > wrote in message
> ...
> > Why do we age?
> >
> > My niece asked me this the other day. I said that I seemed to recall
that
> > it
> > is due to damage caused by free radicals.
> >
> > Is this correct?
> >
>
>
> In part. However, there are complex mechanisms that decide when it's time
> for the cell to check out. You might like a little book called A Means to
> an End: The Biological Basis of Aging and Death, by William Clark.
>
>
> Krista

Thank you.

Steve Freides
October 5th 04, 10:21 PM
"freddy" > wrote in message
...
> Why do we age?
>
> My niece asked me this the other day. I said that I seemed to recall
> that it
> is due to damage caused by free radicals.

I age because of my children.

My wife ages because of me.

My children age because we continue to feed them.


and the seasons they go round and round
and the painted pony goes up and down
We're captive on a carousel of time
we can't return we can only look behind
from where we came and go round and round and round
in the circle game

-S-
http://www.kbnj.com

Rutabaga22
October 5th 04, 10:28 PM
William Clark's book on cell death will give the precise answer, but a good
start is that we are machines made by DNA for the purpose of making more DNA.
Once we've done that, by reproducing ourselves, nature doesn't care about us
any more.

Cynical but, as far as I can tell, true.

Richard Smith
October 6th 04, 02:00 AM
"Steve Freides" > wrote in message
...
> "freddy" > wrote in message
> ...
> > Why do we age?
> >
> > My niece asked me this the other day. I said that I seemed to recall
> > that it
> > is due to damage caused by free radicals.
>
> I age because of my children.
>
> My wife ages because of me.
>
> My children age because we continue to feed them.

Nice summation Steve, thanks.

Think I'll go cut my throat.

But since it's inevitable I may as well climb the UT tower and have a go
with some long guns first.

RIchard
>
>
> and the seasons they go round and round
> and the painted pony goes up and down
> We're captive on a carousel of time
> we can't return we can only look behind
> from where we came and go round and round and round
> in the circle game
>
> -S-
> http://www.kbnj.com
>
>

elzinator
October 6th 04, 02:11 AM
On Tue, 5 Oct 2004 17:21:14 -0400, Steve Freides wrote:
>"freddy" > wrote in message
...
>> Why do we age?
>>
>> My niece asked me this the other day. I said that I seemed to recall
>> that it
>> is due to damage caused by free radicals.
>
>I age because of my children.
>
>My wife ages because of me.
>
>My children age because we continue to feed them.
>
>
>and the seasons they go round and round
>and the painted pony goes up and down
>We're captive on a carousel of time
>we can't return we can only look behind
>from where we came and go round and round and round
>in the circle game

Joni Mitchell


---------------------------------
Teddy Roosevelt for President!!

Peter Webb
October 6th 04, 08:08 AM
"Rutabaga22" > wrote in message
...
> William Clark's book on cell death will give the precise answer, but a
> good
> start is that we are machines made by DNA for the purpose of making more
> DNA.
> Once we've done that, by reproducing ourselves, nature doesn't care about
> us
> any more.
>
> Cynical but, as far as I can tell, true.

A somewhat circular answer.

If we didn't age, we could continue to reproduce, and make more DNA.

In evolutionary terms, aging and death are bad things - they restrict our
biological capacity to reproduce - which makes their existence even more of
a mystery.

John HUDSON
October 6th 04, 08:27 AM
On Wed, 6 Oct 2004 17:08:57 +1000, "Peter Webb"
> wrote:

>
>"Rutabaga22" > wrote in message
...
>> William Clark's book on cell death will give the precise answer, but a
>> good
>> start is that we are machines made by DNA for the purpose of making more
>> DNA.
>> Once we've done that, by reproducing ourselves, nature doesn't care about
>> us
>> any more.
>>
>> Cynical but, as far as I can tell, true.
>
>A somewhat circular answer.
>
>If we didn't age, we could continue to reproduce, and make more DNA.
>
>In evolutionary terms, aging and death are bad things - they restrict our
>biological capacity to reproduce - which makes their existence even more of
>a mystery.

You make a profound point Peter!

ray miller
October 6th 04, 11:13 AM
>If we didn't age, we could continue to reproduce, and make more DNA.
>
>In evolutionary terms, aging and death are bad things - they restrict our
>biological capacity to reproduce - which makes their existence even more of
>a mystery.

Look at it from the other direction. Aging and death are ubiquitous,
and since nature's failures never last long there MUST be a good
evolutionary reason for aging and death.

I suggest that change is one key. If life were immortal it wouldn't
change fast enough.
Another explanation may be population vs resources. If life were
immortal it would get to the point where resources ran out. It may be
more economical for individuals to age and die rather than compete for
finite resources.

But what do I know?

Ray
--
rmnsuk
273/182/182

rick++
October 6th 04, 04:35 PM
A body only needs to stay intact long enough to create and raise the next
generation. Then it can go to hell. And it does.

bc
October 6th 04, 04:40 PM
ray miller > wrote in message >...
> >If we didn't age, we could continue to reproduce, and make more DNA.
> >
> >In evolutionary terms, aging and death are bad things - they restrict our
> >biological capacity to reproduce - which makes their existence even more of
> >a mystery.
>
> Look at it from the other direction. Aging and death are ubiquitous,
> and since nature's failures never last long there MUST be a good
> evolutionary reason for aging and death.
>
> I suggest that change is one key. If life were immortal it wouldn't
> change fast enough.
> Another explanation may be population vs resources. If life were
> immortal it would get to the point where resources ran out. It may be
> more economical for individuals to age and die rather than compete for
> finite resources.
>
> But what do I know?

I agree with Ray. From a philosophical poin of view, valuing the
species over the individual, death is important for evolution of the
species.

- bc

aj
October 6th 04, 05:45 PM
On 2004-10-06, ray miller > wrote:
>>If we didn't age, we could continue to reproduce, and make more DNA.
>>
>>In evolutionary terms, aging and death are bad things - they restrict our
>>biological capacity to reproduce - which makes their existence even more of
>>a mystery.
>
> Look at it from the other direction. Aging and death are ubiquitous,
> and since nature's failures never last long there MUST be a good
> evolutionary reason for aging and death.
>
> I suggest that change is one key. If life were immortal it wouldn't
> change fast enough.
> Another explanation may be population vs resources. If life were
> immortal it would get to the point where resources ran out. It may be
> more economical for individuals to age and die rather than compete for
> finite resources.
>
> But what do I know?
>
> Ray

Well, you're pretty much dead on.

--
-aj
I'll mess with Texas.

Lee Michaels
October 6th 04, 05:52 PM
"aj" > wrote

> On 2004-10-06, ray miller > wrote:
> >>If we didn't age, we could continue to reproduce, and make more DNA.
> >>
> >>In evolutionary terms, aging and death are bad things - they restrict
our
> >>biological capacity to reproduce - which makes their existence even more
of
> >>a mystery.
> >
> > Look at it from the other direction. Aging and death are ubiquitous,
> > and since nature's failures never last long there MUST be a good
> > evolutionary reason for aging and death.
> >
> > I suggest that change is one key. If life were immortal it wouldn't
> > change fast enough.
> > Another explanation may be population vs resources. If life were
> > immortal it would get to the point where resources ran out. It may be
> > more economical for individuals to age and die rather than compete for
> > finite resources.
> >
> > But what do I know?
> >
> > Ray
>
> Well, you're pretty much dead on.
>
I find it interesting that science fiction has three takes on this topic.

One is stories about societies that have rigid controls on reproduction and
population.

Another is societies that have lost their ability to reproduce.

The other is a society with limited ability to reproduce and, again, have
rigid controls on reproduction and population.

aj
October 6th 04, 07:25 PM
On 2004-10-06, Lee Michaels > wrote:
>
> "aj" > wrote
>
>> On 2004-10-06, ray miller > wrote:
>> >>If we didn't age, we could continue to reproduce, and make more DNA.
>> >>
>> >>In evolutionary terms, aging and death are bad things - they restrict
> our
>> >>biological capacity to reproduce - which makes their existence even more
> of
>> >>a mystery.
>> >
>> > Look at it from the other direction. Aging and death are ubiquitous,
>> > and since nature's failures never last long there MUST be a good
>> > evolutionary reason for aging and death.
>> >
>> > I suggest that change is one key. If life were immortal it wouldn't
>> > change fast enough.
>> > Another explanation may be population vs resources. If life were
>> > immortal it would get to the point where resources ran out. It may be
>> > more economical for individuals to age and die rather than compete for
>> > finite resources.
>> >
>> > But what do I know?
>> >
>> > Ray
>>
>> Well, you're pretty much dead on.
>>
> I find it interesting that science fiction has three takes on this topic.
>
> One is stories about societies that have rigid controls on reproduction and
> population.
>
> Another is societies that have lost their ability to reproduce.
>
> The other is a society with limited ability to reproduce and, again, have
> rigid controls on reproduction and population.

Rishathra.

--
-aj
I'll mess with Texas.

Rutabaga22
October 6th 04, 10:53 PM
>> >If we didn't age, we could continue to reproduce, and make more DNA.
>> >
>> >In evolutionary terms, aging and death are bad things - they restrict our
>> >biological capacity to reproduce - which makes their existence even more
>of
>> >a mystery.
>>
>> Look at it from the other direction. Aging and death are ubiquitous,
>> and since nature's failures never last long there MUST be a good
>> evolutionary reason for aging and death.
>>
>> I suggest that change is one key. If life were immortal it wouldn't
>> change fast enough.
>> Another explanation may be population vs resources. If life were
>> immortal it would get to the point where resources ran out. It may be
>> more economical for individuals to age and die rather than compete for
>> finite resources.

This sounds right - there is some literature on evolution and the death of the
individual. Perhaps death evolved as an adaptation - amoebae etc. don't die,
they divide (I think). More advanced species seem to require their individuals
to die. It's probably all in Dawkins, so before pontificating any further I
should go back and read his stuff.

Peter Webb
October 7th 04, 08:29 AM
"Rutabaga22" > wrote in message
...
>>> >If we didn't age, we could continue to reproduce, and make more DNA.
>>> >
>>> >In evolutionary terms, aging and death are bad things - they restrict
>>> >our
>>> >biological capacity to reproduce - which makes their existence even
>>> >more
>>of
>>> >a mystery.
>>>
>>> Look at it from the other direction. Aging and death are ubiquitous,
>>> and since nature's failures never last long there MUST be a good
>>> evolutionary reason for aging and death.
>>>
>>> I suggest that change is one key. If life were immortal it wouldn't
>>> change fast enough.
>>> Another explanation may be population vs resources. If life were
>>> immortal it would get to the point where resources ran out. It may be
>>> more economical for individuals to age and die rather than compete for
>>> finite resources.
>
> This sounds right - there is some literature on evolution and the death of
> the
> individual. Perhaps death evolved as an adaptation - amoebae etc. don't
> die,
> they divide (I think). More advanced species seem to require their
> individuals
> to die. It's probably all in Dawkins, so before pontificating any further
> I
> should go back and read his stuff.

Unfortunately, Dawkins provides the very reason why this explanation is
wrong.

Evolotion is not determined by what is good for the species, it is
determined by what is good for the individual.

I absolutely agree that death is good for the species, for all the reasons
mentioned above (eg it allows more resources for future generations that may
be bettewwr adapted). But it is very bad for the individual (doh). Imagine
we are all immortal, and a gene for death appears. Do you think that the
individual carrying this gene would be more or less likely to have lots of
children than those without the gene (the rest of the population that is
immortal)?

Conversely, imagine that an individual suddently appeared in today's world
that somehow was immortal and didn't age. With 100,000+ years to screw
around in - and maybe 5,000 wives - they would certainly have lots of
opportunity to pass on the gene. It would be bad for the species as a whole,
as the immortals would push us normals to extinction very quickly, and so
the genetic variability in the human species would disappear. But evolution
doesn't care about what happens to a species; it only cares about who is
successful in making copies of their DNA.

If you are looking for an explanation of aging and death, and trying to use
evolution as an argument, then its going to have to be a whole lot more
subtle than this, because being immortal (and not aging) would be a HUGE
evolutionary advantage, and on the face of it would rapidly displace the
gene lines that didn't include this benefit.

ray miller
October 7th 04, 11:44 AM
>Evolotion is not determined by what is good for the species, it is
>determined by what is good for the individual.

Yes. That's how species explosions occur - cf rift lake cichlids. One
or two generalized species in a new environment produce hundreds of
new species in a very short timescale (gelologically speaking).

>If you are looking for an explanation of aging and death, and trying to use
>evolution as an argument, then its going to have to be a whole lot more
>subtle than this, because being immortal (and not aging) would be a HUGE
>evolutionary advantage, and on the face of it would rapidly displace the
>gene lines that didn't include this benefit.

Mortallity is the norm so immortality CAN'T have an evolutionary
advantage. In 4 billion years it must have come up at least once. You
may be right that the advantage is beyond our comprehension, but it's
not subtle. There are some plants that have lifespans approaching
immortality. Does this break my arguement?

I think there is an analog to immortality in higher animals.
There are a handful of species that exist as female only
(parthenogenesis). All individuals have the same genes (clones) and
pass them on intact. Although these species are well adapted to their
niche (they are usually quite specialized) they don't react to change
very well, and so the species become extinct very quickly in
geological timescales.

Ray

rick++
October 7th 04, 04:07 PM
> If you are looking for an explanation of aging and death, and trying to use
> evolution as an argument, then its going to have to be a whole lot more
> subtle than this, because being immortal (and not aging) would be a HUGE
> evolutionary advantage, and on the face of it would rapidly displace the
> gene lines that didn't include this benefit.

Most single-cell organisms are immortal and die through starvation,
being eaten, or starvation. Almost all multicellular organisms that
arise through a single-cell zygote (sperm with egg) die. (This excludes
multicellular aggregates like algae, slime, lichen, etc.) Most zygote derived
organisms have pre-programmed partial cell death as they grow.
So there is some connection between sexually reproducing organisms and death.

Several science writers have proposed the converse: the price of immortallity
may be asexuallity. E.g. Ann Rice's vampires.

Bob MacWilliam
October 7th 04, 06:15 PM
ray miller > wrote in message >...
> >Evolotion is not determined by what is good for the species, it is
> >determined by what is good for the individual.
>
> Yes. That's how species explosions occur - cf rift lake cichlids. One
> or two generalized species in a new environment produce hundreds of
> new species in a very short timescale (gelologically speaking).
>
> >If you are looking for an explanation of aging and death, and trying to use
> >evolution as an argument, then its going to have to be a whole lot more
> >subtle than this, because being immortal (and not aging) would be a HUGE
> >evolutionary advantage, and on the face of it would rapidly displace the
> >gene lines that didn't include this benefit.
>
> Mortallity is the norm so immortality CAN'T have an evolutionary
> advantage. In 4 billion years it must have come up at least once. You
> may be right that the advantage is beyond our comprehension, but it's
> not subtle. There are some plants that have lifespans approaching
> immortality. Does this break my arguement?
>

Longevity might confer an evolutionary advantage to a point, but
immortality in the face of scarce resources would never be able work
physically and it would seem that birthrate and therefore genetic
variation would grind to a halt, therefore impeding success as a
species. The lack of genetic variation becomes a serious extinction
risk. Something doesn't seem quite right about that argument though.

It could be that the same processes that make us able to reproduce
effectively and become genetically variable, also are responsible for
aging too. It could be that these processes are
chemically/biologically one in the same so that you can't get genetic
variation (and hence long-term success as a species) without aging and
death. The underlying rules of the physical universe could dictate
that reproduction is the same process as death at it's
physical/chemical core.

As Carl Sagan said (or something like it) "The physical universe is
not required to conform to eeeuuumannn ambition"

Bob

aj
October 7th 04, 08:13 PM
On 2004-10-07, rick++ > wrote:
>> If you are looking for an explanation of aging and death, and trying to use
>> evolution as an argument, then its going to have to be a whole lot more
>> subtle than this, because being immortal (and not aging) would be a HUGE
>> evolutionary advantage, and on the face of it would rapidly displace the
>> gene lines that didn't include this benefit.
>
> Most single-cell organisms are immortal and die through starvation,
> being eaten, or starvation. Almost all multicellular organisms that
> arise through a single-cell zygote (sperm with egg) die. (This excludes
> multicellular aggregates like algae, slime, lichen, etc.) Most zygote derived
> organisms have pre-programmed partial cell death as they grow.
> So there is some connection between sexually reproducing organisms and death.
>
> Several science writers have proposed the converse: the price of immortallity
> may be asexuallity. E.g. Ann Rice's vampires.

You misstyped 'thinly vieled homosexuality'.

Which, by the way, is my solution to human population growth:

Mandidtory homosexuality.

It worked for the Spartans. If by 'worked' you accept that it acheived
the opposite of what they were trying to do: breed more warriors. There
are rumours that it was such a problem that new brides had to shave
their heads and wait for their new hubbies in the dark, to simulate
being a widdle boy.

--
-aj
Better than a 'one child' policy.

DZ
October 8th 04, 06:12 AM
Peter Webb > wrote:
> "Rutabaga22" > wrote
>> This sounds right - there is some literature on evolution and the
>> death of the individual. Perhaps death evolved as an adaptation -
>> amoebae etc. don't die, they divide (I think). More advanced
>> species seem to require their individuals to die. It's probably
>> all in Dawkins, so before pontificating any further I should go
>> back and read his stuff.
>
> Unfortunately, Dawkins provides the very reason why this explanation is
> wrong.
>
> Evolotion is not determined by what is good for the species, it is
> determined by what is good for the individual.

This phrase is not controversial brecause it is too vague. Everything
around an individual can be considered its environment. If environment
is somehow abused, or equivalently, if the species to which the
individual belongs is harmed due to individual's behavior, the species
goes extinct. And so are individual's genes.

Most lineages become extinct and what we see around are examples of
evolutionary success - the succession of species survived to this day.
It does not matter how you define the process of extinction of
populations and species - selection on the level of species/groups,
whatever.

By the way, "group selection" is nowhere near being a controversial
concept. Things like maintaining optimal recombination rates cannot be
explained without invoking selection on the group level. It's the
extent of it that is disputed.

> I absolutely agree that death is good for the species, for all the reasons
> mentioned above (eg it allows more resources for future generations that may
> be bettewwr adapted). But it is very bad for the individual (doh). Imagine
> we are all immortal, and a gene for death appears. Do you think that the
> individual carrying this gene would be more or less likely to have lots of
> children than those without the gene (the rest of the population that is
> immortal)?
>
> Conversely, imagine that an individual suddently appeared in today's world
> that somehow was immortal and didn't age. With 100,000+ years to screw
> around in - and maybe 5,000 wives - they would certainly have lots of
> opportunity to pass on the gene. It would be bad for the species as a whole,
> as the immortals would push us normals to extinction very quickly, and so
> the genetic variability in the human species would disappear. But evolution
> doesn't care about what happens to a species; it only cares about who is
> successful in making copies of their DNA.

These are not very relevant examples. What's important is non-decrease
in the number of gene copies per unit of time. It doesn't matter
whether a gene is passed through single long-lived or multiple
short-lived individuals.

> If you are looking for an explanation of aging and death, and trying to use
> evolution as an argument, then its going to have to be a whole lot more
> subtle than this, because being immortal (and not aging) would be a HUGE
> evolutionary advantage, and on the face of it would rapidly displace the
> gene lines that didn't include this benefit.

There is no evolutionary advantage. Otherwise there would be a
historic trend - modern species would tend to be long-lived. The issue
is that the long-lived individuals are not as adaptable with respect
the changing environment.

Look at birds vs. rodents - similar metabolism rates and sizes, but
the life span of birds is often 5 times higher. Are birds just
happened to be better assembled (like Honda Civic vs. Ford Tempo)?

Consider recent experimental examples where even just single mutations
in yeast and worms are capable of *doubling* life span without
apparent reduction in fitness. What this shows is that there is a lot
of potential for increasing life span in wild species, and certainly
genetic polymorphisms with respect life span exist. However, these
mutations do not become fixed in the wild.

There isn't necessarily a selection for the certain species-specific
lifespan, but there is selection favoring mechanisms for maintaining
organismic integrity throughout the age of expected reproduction. Then
the genes decide they can no longer be bothered about maintaining
protection and let it all fall apart.

DZ

Lucas Buck
October 9th 04, 11:44 AM
On 6 Oct 2004 08:40:17 -0700, (bc) wrote:

>ray miller > wrote in message >...
>> >If we didn't age, we could continue to reproduce, and make more DNA.
>> >
>> >In evolutionary terms, aging and death are bad things - they restrict our
>> >biological capacity to reproduce - which makes their existence even more of
>> >a mystery.
>>
>> Look at it from the other direction. Aging and death are ubiquitous,
>> and since nature's failures never last long there MUST be a good
>> evolutionary reason for aging and death.
>>
>> I suggest that change is one key. If life were immortal it wouldn't
>> change fast enough.
>> Another explanation may be population vs resources. If life were
>> immortal it would get to the point where resources ran out. It may be
>> more economical for individuals to age and die rather than compete for
>> finite resources.
>>
>> But what do I know?
>
>I agree with Ray. From a philosophical poin of view, valuing the
>species over the individual, death is important for evolution of the
>species.


"And when you're dead, you've lost a very important part of your life."
Brooke Shields