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Age A Byproduct of Cancer Defense?
A reader writes "The International Herald Tribune has an article which says, in brief: they have discovered that aging in mice seems to be a byproduct of the chemicals that prevent cancer" If true, that's quite a double edged sword - avoid death, to cause it later.
Anti-Aging Pills Business Plan:
In the environment where we did most of our evolving very few people lived to "old age" before succumbing to a number of other dangers, so something that kept cancer at bay for a while at the price of guaranteeing death after a few decades probably seemed like a good deal. Kind of like the 640k limit. "That ought to be enough for everybody."
Actually, I was trying to be Insightful, not Funny.
Maybe that's why we age at all. We could have evolved to reduce the chances of developing cancer with the result of aging. Might explain all those ancient texts that have people thousands of years old.
I can't spell or type, but that doesn't mean I'm unusually stupid.
"Too much p53 and you get this aging effect. Too little and you get cancer. My guess is that evolution has evolved just the right level."
Would somebody explain to me how evolution would play in this finely-tuned scenario? In the U.S. our average lifespan is over 70 years, yet most women pass menopause around age 45. There's a 25 year lifespan discrepancy, in which evolution has no effect, because the population (at least of women) can't reproduce!
Well, in that case, the ??? actually equals "Market to a man's fear of death and desire for immortality". People have been making money off of that for thousands of years.
It hurts when I pee.
Does this mean that since modern day man has increased contact with carcinogens, evolution will now favor those with higher cancer resistance and therefore shorter life-spans?
"when the going get's wierd the wierd turn pro." -hst
Not necessarily ... if we can determine the mechanism, it might be possible to modify the P53 protein to prevent the aging effect.
You could think of death as the end of cell growth, whereas cancer is cell growth gone out of control.
Silly mortals! I propose that whomever designed us intentionally created these apparent paradoxes to force all doubters to eventually believe.
"What is the sound of one belly slapping?"
Do you have any links/info that corroborate your assertion?
A *lot* of people I know would have died much earlier than they did (or they aren't dead yet, me included) due to illnesses they contracted after age 5...
Considering all of the people older than 5 going in hospitals for heart surgery, appendicectomies, assorted cancer removals etc. that go on living for decades afterwards (rather than dying), I find it counter intuitive that a lower infant mortality is the only reason why the average lifespan has increased so much during the past decades.
Note that I don't necessarily think it's wrong, mind you, just very counter intuitive, that's why I'd like to know if you have some sort of proof to back your statement with.
-- the cake is a lie
at the same time, many of the carcinogens are also the same compounds that cause aging. A familiar class of these compounds include free radicals and anything else that causes oxidation.
It has been shown that organisms unable to manage certain environmental toxicants (as in knockout mice that can no longer tolerate heavy metals) age more quickly, and are immunosuppressed.
Toxicants cause mutations directly in DNA, or interferes with protein assembly. The presence of toxicants also shift a cell's energy utilization since the cell must now use more energy to either remove or break down the toxicant. Many toxicants (such as heavy metals) can neither be removed nor processed. Higher energy utilization means energy production increases, and that increases oxidative stress (as in oxidation of sugars, etc.). Thus, the cell can not do its "job" correctly, because it has to deal with all the other crap being thrown at it. Finally, after age 21, you stop growing, so all the cells in your body are there to maintain homeostasis. When cells can no longer do their jobs efficiently, stuff starts breaking (as in cartilage breakdown in joints to cause arthritis, or fibroblasts can no longer maintain rigid cytoskeletons and cause wrinkles and muscle cells lose their tone; nephrons become unable to repair themselves and kidney failure results; neurons can no longer flush out incorrectly produced proteins and alzheimer's sets in).
All joking aside, this shows how flawed the study of human cancer in rodents is. It's true, many rodents are very succeptible to cancer, most of the time from stuff which is not carcinogenic to a person. So, if we relied on rats to tell us about human cancer, we'd probably have to live in bubbles, but we, uh, don't.
"We kill to cure, with cures that kill" - Skinny Puppy
Err, two words: Organized Religion
If someone has been making money for thousands of years, I'd say their claims are pretty well-founded
Well, that's debatable.. I'm not going there, though.. :)
Shayne
Today I didn't even have to use my AK; I got to say it was a good day -- Icecube
Cells are dividing into more cells in our body at every given moment (e.g., skin sloughs off and more is "remade"). For a cell to divide, it's DNA must be replicated (i.e., copied). The molecular mechanisms that replicate DNA are very precise, but not perfect, even with the so called "error-correcting enzymes". This leads to maybe 1 error every 100,000 base pair copied.
Don't worry, most mistakes, or mutations, are trivial, or if dangerous, will cause that cell to die or be unable to reproduce, so that mutation never gets passed on. But because so much DNA replication is going on in the body, somewhere, somehow, a mistake will lead to a mutant cell that has a slight advantage. This new cell might be able to divide fast, or resist molecules that check for fast dividers, or be able to live without being next to similar cells.
In fact, many cancers seem to require a few distinct mutations before it can grow fast, split off, swim around in the bloodstream and still live, and finally be able to live off of whatever new cells it attaches to -- this endstage is called metastasized cancer, cancer that has traveled to the rest of the body.
So the reason why we get cancers is almost because of Darwinan selection in the body: eventually, the most fit mutations will be able to survive and grow irregardles of how our normal body wants to function, and thus that cancer overtakes and drains our body's normal resources.
So it actually makes sense that the longer you live, the more likely you will die of cancer, even without this new discovery of a potential mechanism. In fact, for adults over 55 years of age, the most common cause of death is cancer (even greater than heart disease, which is second). There is a subset of cancers known as "childhood cancers" that affect children, usually because of a genetic defect at birth that dooms them early. For "genetically normal" people, it is the stochastic process of accumulated mutations that, almost inevitably, resolves in cancer. In other words, everyone will get cancer if they lived long enough to get it.
The reason being that thermodynamics (or chaos theory, or whatever) says that you're wrong. Any system as complex as a living cell, even something so simple as a yeast cell or E coli can not maintain that level of organisation for long. The cell is very thrifty with its organization, to be sure, but it is not infinitely so. That's why reproduction and evolution are so critical, because no single system can survive by itself for too long, so it must rebuild itself from scratch. Yes, you can put these systems in to hibernation, but that isn't really life functioning in any way shape or form until it's revived.
And of course pre-programmed cell death wasn't present in single cell organisms, it'd be counterproductive for an E coli to simply kill itself. Preprogrammed cell death does not kill the entire organism, and it obviously be detrimental if it did.
And as for sex and evolution evolving together, there are single celled organisms that have sex via plasmids. Granted, it might not be the "one chromosome from each parent" that we are used to in humans, but it is still genetic exchange by conjugation. There is no apoptosis here either.
"I may not have morals, but I have standards."
From the post:
> If true, that's quite a double edged sword - avoid death, to cause it later.
Shouldn't that be to cause it sooner?
No, the poster was right. Cancer will kill you faster than old age*. So even though aging also kills you, growing old allows you to live longer. Quite preferable to the alternative, if you ask me.
* Assuming you don't get it when you are old. If you get cancer at the age of 95, you're pretty much screwed no matter what.
Remember "Bring 'em on"? *sigh