noahfor

if the body can grow and maintain itself for 30 years then why not forever, gotta be genetic

tecoyah

There is a theory....bordering on fact, that cells degrade themselves over time in an attempt to prevent abnormalities. They commit suiscide, so to speak. Some genetic studies are attempting to find the specifics behind cell death, and reverse it.
As of yet, there are a couple hundred experiments that have had mixed results with fruit flies, and mice. Still, we are a long way from immortality, Give it a couple more decades.

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filtherton

As much as i shudder with anticipation when it comes to technology i think reversing the aging process, unless balanced by birthrate quotas and universal healthcare, is a really bad idea.

Rodney

Well, glomming together info from a dozen hazily-remembered newspaper articles...

There are at least two factors (at _least_) at work here. One that scientists are pretty sure of is genetic damage, caused both by the environment and by the cell copying mechanism (y'know, like making a xerox of a xerox; the next copy just isn't as good). The human cellular mechanism for copying itself is pretty good at error checking, which is why we leave 70+ years instead of 10-15 for most dogs and cats. But it's not perfect. Over time, the genes in more and more cells get degraded enough that they work imperfectly, stop serving a useful purpose but don't exactly die (called "senecscent cells," which is like calling thems senile), or go wrong in a spectacularly bad way (cancer). All of which causes bodily system to lose efficiency and fail, eventually causing death.

Now there are some people in the world, particularly Okinawa for some reason, who have really, really good cellular repair systems. There's one guy in particular whose genes are as undamaged as most people's are at 20. And except for having really terrible skin (sun damage, moles), he's built like a fit 25-year-old. He's a diver -- one of those fishermen who keep nets and traps under the water, and dive down 30-40 feet to load and unload them _without tanks_. He does this every day, even now.

But he's still going to die within 40 years or so because of each cell's built-in suicide switch, the telomeres.

The DNA molecule which holds the genes itself is described as a double helix: two "ropes" of genes wrapped around each other and attached to one another at matching genes. The ends of these ropes (which don't hold functioning genes) are called the telomeres. They're literally the shoelaces of the DNA. The telomeres of each strand loop around each other in a sort of knot and hold the DNA together.

Each time the DNA replicates itself in cell division, it loses a little bit off the end of each telomere. When the telomeres become too short to form the knot during cell replication, the cell commits suicide. I'm not sure why, and I'm not sure if anybody is. But at any rate, in human beings this usually happens after 50-55 cell replications. And since cells generally replicate themselves approximately every two years, that's why practically no one lives past 120, and not past much that ever.

Some people have done experiments in which they were able to extend the telomeres of genes in animal cells and keep them going on past the usual number of replications for that creature. So I suppose it'd be possible, at some point in the medium to distant future, to renew everybody's telomeres.

Like I said, these are two factors that people think account for aging and death. Who wants to bet there are many more?

Yakk

The best theory I've heard why telomers exist is an anti-cancer mechanism.

Lets say a cell goes nuts, and starts replicating every minute.

At the same time, your immune system kills 25% of the cancer cells every minute.

So, every 2 minutes, every cancer cell has replicated twice, and there are twice as many.

In 1 hour, there will be a million copies of that cancer cell. But, it will have replicated 60 times. Oh my, it just hit the telomere limit! Bye bye tumor.

Human beings are, biologically, just carriers for our gamites (germ-line cells, sperm production cells and eggs). The rest of the body is intended to shut down rather than live forever, because reproduction is the important part. The telomeres help the body make it to reproduction, and clean up the waste humans that live past reproductive age.

We have gotten to a point beyond this. Evolution applies more to our culture and our minds and thoughts than it does to our biology. A human being who cannot have children still can influence the culture minds and thoughts of other humans, they are no longer a waste product.

A friend of mine is fond of the fact that over 50% of the humans who have ever lived are still alive. Gives him a decent chance at immortality, if that ratio keeps up. =)

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Last edited by JHVH : 10-29-4004 BC at 09:00 PM. Reason: Time for a rest.

:::OshnSoul:::

Our bodies are supposed to last forever, crazy huh? But that we has humanity as a whole and as individuals have made choices that shorten our lifespan here on earth. Pollution, drugs, eating habits, drinking, etc.

sexymama

Without death, life would be meaningless.

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It's not about being perfect; it's about developing some skill at managing imperfection.

Stompy

Hm... interesting points, but think of it this way:

The average human lifespan keeps expanding. Living till 70 was unheard of nearly 100 years ago, just like living to 50 was unheard of just 100 years before that. Now it's pretty common that you see 70-80 year olds with 100 being the "wow" age.

I think it's all based on the cells surrounding environments.. disease, nutrition, etc. I mean, it wasn't until farily recently that exercise (particularly cardio) was recommended as part of a healthy lifestyle.

Based on that, it's my opinion that cells have an indefinite lifespan, but it's just how they're treated that determines when your body as a whole kicks out. Of course, there are exceptions and abnormalities like cancer.

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:::OshnSoul:::

death is only a passing stage, nothing less. it is our exit out of this experience and an entrance to our next experience. I don't fear death, because I know it doesn't exist. So, truly, we never "die", but our bodily forms were originally intended to last forever, but in the physical world we have created ways to cause them to have a shorter-lifespan.