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Memories of the 28th Century

How Long

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For several reasons, I sometimes wonder how long humans can live, and I also wonder whether death may be voluntary. In my limited experience, people often seem to have an innate sense for how long they will live, and they are relatively accurate, and that has led me to wonder how long humans can live. There was that Chinese herbalist, Li Ching-Yuen, who lived more than 250 years. And there was Old Tom Parr, an Englishman who lived 152 years. And there are others who were 150 years or older when they died. The recent, fully documented old people gave up before they got to 130, and most of them didnít even get to 120.

Some of the recent research suggests that there is a maximum age of somewhere in the range from 600 to 1200 years. Thatís a wide spread, but it provides a goal. The limiter is the deterioration of telomeres. Telomeres and the ends of DNA strands, and they shorten every time the DNA is replicated in cell reproduction. When they are gone, the cell canít reproduce, so it dies. There are some animals that redo the deterioration, but they are sponges and a few similar things. Sponges dissolve into individual cells, and the cells become free swimming one-celled animals for a time, then theyíre assemble, and the cells are like new. I believe that the sponges also may reassemble into more than one sponge. Humans are more complicated, and we donít have the ability to dissemble and reassemble, but humans don't work that way, so we can't make out cells new again, but I think that the subconscious mind operates like the operating system of a computer controlled machine that has parts that can repair other parts. When the order goes out to repair some part, the immune system assembles the necessary parts, takes apart to broken piece, and then it puts together a new piece. It isnít a fast system, but it does work, and it is flexible, and there are some types of flesh that are more difficult to repair, so they take longer. For example, if you have every had an injury that included damaged nerves, then you probably noticed the muscle, skin, etc. repairing to close to the original condition, but the nerve didn't heal, so there was numbness for a long time, but eventually it caught up. Damage to bones and tendons can also take a long time for complete repair.
It isn't the repair time that is a problem, it is the problem that many people don't think that their bodies will repair. That is especially a problem when someone's body starts to malfunction and continues repairing after the work is done. That becomes cancerous and is a problem with some lung cancers and skin cancers. But today, I was thinking more about our expectations of what our bodies will do.
Some people can't imagine living to be very old, because they know that their grandparents and other relatives have died before they reach even 90. In some cases, those are self-fulfilling prophecies, but some people do inherit genes that are not capable of repairing everything forever. We have no way to know for certain whether there is a maximum age for humans; although some researchers have suggested a maximum age as young as 120, even though some documented people have lived for longer than that. There were good documents for Li Ching-Yuen, and there were good documents for Old Tom Parr; it is ironic that Tom Parr died during a visit to some people who had documented his case and wanted to honor him. And there is the guess that humans can't last for more than 1200 years (twelve hundred). Due to other breakdowns, accidents, etc. I have read that actuaries have estimated that 300 is the maximum age, because accidents and crime will get anyone eventually. There's only one way to know for sure, and I am trying to find out.

Another related question has to do with menopause. Other anthropoids do not have menopause. Menopause prevents long-lived women from passing on their age related situation. If the situation were reversed, so that humans only gained the possibility of reproducing after several decades, then people who were prone to most diseases that are considered ďage-relatedĒ would die before they started to reproduce, so those tendencies would tend to die out. For example, type 2 diabetes is often considered age related, and it appears that there are underlying problems that lead to it, but if people with the underlying conditions died before reproducing, then that disease would eventually die off. There are are other tendencies toward disease that would similarly die off.

It is largely speculation, but it is likely that people who live long enough will gain immunity to infectious diseases, and they will either not be susceptible to diseases that are caused by immune responses. If one combines that with the results of eliminating aging on the cellular level, then a life span of more than a thousand years is not out of the question. The hangup is with telomeres. We know how to get telomeres to reconstitute, but treatment with telomerase leads to run-away cell reproduction, which is fatal. Apparently animals' immune systems can treat chromosomes on a single cell to repair one cell, so there should be some way to work around the problem with telomeres.

Aging cells cause many problems from sagging skin to loss of vision and hearing. On the other hand, cardiac arterial plaque is a result of an effective immune system repairing damage to cardiac arteries. The plaque is a sort of scab over the damage. Now we have to find a way to get rid of the scabs.

The most important thing is to keep the telomeres from deteriorating. After we do that, the rest should be easy.

This was going to be about death being voluntary, but I got sidetracked.

His surprising conclusion: if we eliminated aging at the cellular level, humans could live for a millenniumóand potentially as long as 20,000 years.