Why do humans die? I know that everyone does die ultimately, but why does life come to an end? Is it true that mental attitude plays a greater role in longevity than genetics? Longevity has been increasing at rapid rate over the last 100 years, will this continue into the next 100 years?
Well, this thread is certainly going to be an interesting one.
Death happens when the body can no longer keep functioning. Generally, a major system breaks down to the point where it can no longer be fixed and supported by the rest of the body, causing a domino effect of failures causing failures. For example, in a heart attack, the cardiovascular system is destroyed by the death of the heart, meaning the blood supply to the brain is halted, meaning your neurons simultaneously suffocate and starve, killing you.
It is, in the end, a physical process, although the exact seqence of events leading up to the death may be rather hazy depending on when the body was discovered (decay is time-related) and how badly the pieces of the body were mangled by the cause of death.
Mental attitude has a lasting effect on longevity. I’m not aware of the latest research, but the studies I’ve heard of indicate that people who lead mentally and physically active lives lead longer lives and minimize the effects of age. I’m not sure how that relates to heredity.
The past century saw most of its breakthroughs because of the development of the germ theory of disease, leading to sterile practice for hospitals, the discovery and wide use of antibiotics, and, perhaps the most dramatic achievement of 20th century medicine, the invention of the vaccine and widespread vaccination programs. I think for 21st century medicine to top those achievements, genetics and its daughter fields, bioengineering and gene therapy, will have to pay off big time.
Spiritual aspects aside a live human being implies a lot of complex processes that must all work without ever taking a significant break. Disrupt any of those processes enough and the whole system falls apart.
We’ve made progress in longevity by addressing specific causes of death but aging is going to be a tougher nut to crack. As cells age they no longer divide to produce new cells as well.
Padeye, just making cells divide forever is pretty easy. Radiation will do that at random. But that’s called cancer, and it isn’t what we’re aiming for. Aging is more complex.
We all die because we never fill out the warranty cards that came with our bodies, so we can never get Factory authorized service on the parts. 
Zev Steinhardt
Damn Best Buy!
You misunderstood what I said. I didn’t say that cell division stops but that it doesn’t work as well but of course I should have eaborated “New” cells are more likely to have damaged DNA and less ability to repair it as time goes on. I completely agree that aging is a very complex thing and that it will take far more than addressing specific causes of death to bring real increases in longevity.
Zev, I can always count on you for iluminating insights. I can only presume it’s mentioned on the tablet that Mel Books…err, Moses accidentally dropped. 
Short answer: entropy. Longer answer: Basically what Derleth and Padeye were saying. Or, what I like to think of as “The Xerox Effect”. Cells reproduce by making copies of themselves but, as with photocopiers, each copy is a little less precise than the original that produced it. Eventually, you end with a copy that may bear some resemblance to the original, but is no longer useful. When these space-occupying, but non-functional, cells become the majority, the organ or organism which they make up can no longer function properly. Much like a bureaucracy.
I don’t see how it can. People in industrialized countries (and I assume those are the ones you’re talking about, since the life expectancy of third world citizens has not risen that much) rarely die of virulent disease, relatively speaking. There are really only a handful of non-self-induced diseases that kill people who have access to modern medicine, these days. And, most of those don’t take the young. So, I don’t see any way of maintaining that rate of increase. Sooner or later, we just wear out the bodies we inhabit.
What’s the latest on Telomeres? Anyone know?
Last I heard they might hold the key to longevity.
Why is death still passed down from one generation to the next?
“Mental attitude” is such an ephemeral topic that I would guess that it should be very difficult to prove that it has a consistent relationship with longevity.
In the time I’ve spent making visits to retirement homes, it appears to me that there are a fair number of very old folks who are relaxed and optminsted, and a fair number who are bitter and whiney. On the other hand, it appears likely that people who are not in continual pain from a debilitating disease which is slowly killing them would, on average, have a better attitude about life than people who do, and so in that sense, I guess, a positive attitude should be linked to longevity.
As for spirituality generally and longevity, Francis Galton, one of the outstanding pioneers in statistical research, compared the average lifespans of doctors, lawyers and ministers in England. He found that lawyers on average outlived doctors, who outlived ministers.
Life span is more or less proportional to body mass, so that a mouse lives less long than a cat, cat less long than a human…
among the longest living mammals are bowhead whales.
on the other hand tortoises live much longer than their size might indicate.
The mere fact that there are exceptions to this rule of thumb means that it is likely that longevity is not ruled out in nature…
there is no reason why medical science could not extend cell life almost indefinitely…
the real limiter in my view will be the mental state of a human brain after a couple of hundred years of life or more.
Before you hit your thousandth birthday there would be no more room in your brain for memories, so you wpuld have to dump or off load some of them.
As far as entropy goes, that is important, and will certainly prevent you from living forever, but the human body is not a closed system, so can utilise external sources of energy to reorder itself.
While i can’t provide any cites i saw an interesting show on Discovery the other day.
I really have no idea what i’m talking about here, so bear with me OK 
At the end of our DNA, a string of molecules called Telomeres are attached. Each time a cell divides it’s DNA splits and in the process a tiny bit of the Telomere string is lost. When no telomere remains, the cell dies (no longer reproduces).
According to the program scientist have recently accomplished a couple of interesting feats.
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They have discovered that cancer cells does not lose telomere when the cells reproduces. The cell is immortal.
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They have produced an enzyme (forgot the name) which, when inserted into a human cell, keeps the cell DNA from losing telomere and thereby making it immortal. In labs, such cells has shown no sign of decay, nor any signs of not keeping dividing.
Whether or not this enzyme would make an otherwise healthy cell cancerous, they didn’t mention.
“Longevity has been increasing at rapid rate over the last 100 years” because of advances in health technologies and disease control. People were always able to live to 115, its just disease was more untreatable so someone’s chances of reaching old ages were very low. It seems that we’ve now reduced/eliminated most diseases, but we’ve found the “upper-limit” of human lifespan. If you read about it, a good explanation suggested is that we die because there’s really no reason to live… the primary design function of species is to reproduce.
Davebear’s “xerox” theory is just one of many theories on aging. Here’s a list of the leading ones:
Don’t forget the advantages gained by improvements to public health. Water treatment, storm drains, sewage treatment and sanitary landfills are primary contributers to our continued health. Pasteurization and food handling laws are also crucial. We live in a web of regulations and technologies that protect us from diseases that were endemic just a few generations back.
Interesting thought that came to me while reading this thread: there is no evolutionary advantage to immortality. In the beginning, an immortal creature would have quickly fallen prey to a more adaptable creature. Basically, an immortal creature would have done very well if it was top of the line, but the way the current system worked out, that immortal creature wouldn’t have lasted at the top for very long.
And that is all I’ll say, lest this post strays into GD territory (to late?).
Death is hereditory because it allows us to adapt to a changing environment (lamarkian theory was wrong of course).
If earlier species did not die they could not evolve to adapt. Since we evolved from them we have inherited the death trait.
I read in a Reader’s Digest article that the average life expectancy (of an average American I think) should reach 100. In the year 2070. So we should all be dead by then anyway.
Call me crazy, but I think that death is not so much of a burden, as many beleive. Sigmund Freud said that we all have “Death Insticts,” which are instincts that basically drive us toward death. The reason that we have these drives is that everyone always desires to fulfill their needs, and the only way to fulfill them all at once is in death. And that’s all I have.
Simplest answer: entropy.