Muan

In the Bible you read about people who lived for hundreds of years. For example Noah live for around 950 years. What would scientifically allow someone to live for so many years, would our organs need to be vastly different, or would we need to be physically stronger(Bible mentions tall people in the beginning). Can this be explained scientifically or just filed under the 'miracle' tray?

Dark Knight Bob

Your neural pathways would have decayed long before then.

How many myths do you know of with people with super strength or magical powers.

Just add noah to the list of a guy who's super power was living for a thousand years.

Nothing short of robotic implants.

Damburger

Why?

I'm not making an argument for the bible here (I think its a load of crap) but I can't see why the brain can't regenerate like any other organ.

The way neural networks function, individual connections are not that important, and you can lose a surprisingly large number without seriously impairing the function of the network.

Dark Knight Bob

There are a few organs in the body that do not self regenerate. These include the heart the nervous system and areas of the lungs. I can only guess at why this is as i'm not a medical expert, It may be simply these organs require more stability to operate so regeneration allows for too many mistakes to be made. A case of getting it right first time when you're growing up is the best way to ensure these organs work properly.

Over time free radicals (basically oxides and radioactive particles/rays from the environment) eat away at these systems.

This is why you look old. This is due to your DNA being damaged over time.

Stem cells have not evolved to prolong you life because once you've had sex and raised a kid, in genetic terms you no longer need to exist.

in even 300 years I doubt if you'd even be able to interact with other human beings you'd be such a gibbering wreck of crippled motor neruon systems and mental abilities.

Muan

So basically, the key to living for hundreds of years is DNA, would there be any reason to suggest early people were programmed differently?

Epictetus

This is quite an interesting field which I am sure has some advocate in here that knows something about it. I have read in popular mags (Discover, et all) that research is ongoing with lab animals in an attempt to extend their lives by examining and manipulating their cells in one way or another. From the little I have read, the underlying problem with cellular aging and degredation is that during mitosis, the centromere and spindle fibers break down over time. The stuff I have read attempts to prolong the viability of these fibers, thus preserving the cell, thus allowing the animal to extend its life.

Perhaps there are some cellular biologists in here who can respond to this.

travc

Just a heads up... the nervous system (at least parts of it) do regenerate (though not terribly well most of the time). We used to think otherwise, but it has clearly been demonstrated in culture and in vivo. Figuring out how to "switch on" the regeneration in more cells is a current field of research, but only made possible by realizing that some of them are "on" normally (so it is reasonable to expect to be able to encourage more of them into that state).

PS: Growing ganglia in the lab is cool. Attaching them to semicondutor substrates and using them to do computation is really really cool (but doesn't work very well yet.)

DNAunion

The structure is not the centromere, but the telomere. The telomoeres lie at the very ends of our linear chromosomes and from what I know, have two functions. One is to cap the chromosomes to prevent fusions, and the other is to prolong the life of the cell. For the second, the reason they extend the life of the cell is that telomeres consists of numerous repeats of "junk" DNA: it doesn't code for proteins or have regulatory effects (that I am aware of). If just serves as a resevoir of DNA that can be lost little by little without negatively impacting the cell.

During the S phase of interphase, which proceeds mitosis, our DNA is duplicated. The main enzyme involved is DNA polymerase. One "problem" is that it needs a free 3' hydroxyl group to "grab onto" in order to work. When the DNA polymerase gets to the end of the strand, it can't replicate the last few nucleotides. So each cell division leads to a slight shortening of our chromosome. If that end region performed some needed function, we'd be in trouble. But having highly repeated, "junk" DNA there allows for many cell divisions without causing harm.

Some cells use an enzyme named telomerase to extend the telomeres, thus sidestepping the problem we have. So why not just genetically engineer our cells to produce telomerase? Besides problems with genetic engineering, scientists believe that the cells may become immortal, like cancer cells. So the fix may cause more harm than good.

PS: I haven't followed this for some years. I don't know if more-recent research has confirmed or rejected a possible link to cancer.

DNAunion

Many parts of the nervous system can "regenerate" in one form or another.

For example, if a peripheral nerve is transected, the distal portion is going to die. But if the two cut ends can be rejoined, the axons in the proximal portion can grow out into the nerve "wrapping" and replace the dead axons, reaching back out to the effectors and restoring function.

Also, the neuroglia of the brain "regenerate": new neuroglia cells are produced all the time. In fact, cancers of the brain are usually associated with adnormal "regeneration" of neuroglia.

The main cells that were thought not to "regenerate" are the actual neurons of the brain, which are far outnumbered by neuroglia. However, I believe back around 1999, it was found that these can "regenerate" (i.e., new neurons in the brain can be produced). But I don't know how common this is: I believe it is still not the norm.

Epictetus

I just had a buddy who was a paraplegic from a snowboarding accident. He travelled to China where they injected his spinal column with stem cells in an attempt to do what you have described. He is getting some limited improvement in his sensory tracts, though I am not sure if the motor tracts are responding as well. At any rate, it is more than what he was offered here: i.e. live with it.