> I don't really want to debate whether or not this is possible or likely (nobody can say for certain, obviously).

Which is a shame, really, as I think this is a very interesting topic for debate. How *would* you increase the longevity of a human being on a cellular level?

Cells contain their own little lifetimers, telemers, which shorten with replication - they count down the number of replications before the cells will undergo apoptosis. Trying to alter the life cycle of the cell by genetic manipulation, using an external agent to replace the telemer or alter your DNA to make the cell immortal is a bit risky - it would be like infecting yourself with a virus that causes cancer (cancers are cells that have no self-regulation). Also the change would have to effected across the ENTIRE body to stop your natural defence mechanisms from rejecting the new cells - your immortality drugs would have to be tuned to support every specialised cell in the body, delivered to the appropriate site within the body, and then all act as a single unit to change your body into Mumm-Ra, or whatever. Even a tiny fraction of this sort of control would be a fantastic leap forward in drug delivery and design.

So what about stem cell research - cells that can specialise into any organ? Well, once you get past the pro-life lobbyists, you have the potential to genetically modify the cells to grow a new organ to replace your old, worn out one. But the "spare parts on demand" idea doesn't quite fit immortality - would you be able to replace every single part of your body as it aged?

What about your brain - it kills off cells in order to create the connections that make up memories. You couldn't just replace that in a hurry - fitting it into a new, cloned body wouldn't be a satisfactory answer, either - the cells are still self-regulating and will eventually die.
How about downloading your mind into a computer, which the new clone can access, merging your memories with the new mind? Well, that brings us to the question of what the mind is? Will downloading your memories into a box transfer your consciousness as well, or is self awareness an aretefact created by occupying a body? How do you know (in your new body) that you're the same person you were before?

I think it's a fascinating problem, with many possible answers and innumerable problems to deal with along the way. I don't think we'll ever attain "immortality" other than that achieved by passing our genetic code onto the next generation, but the knowledge that could be gained from a little understanding of the possible avenues could prove a massive boon for mankind in general.

>What I'm more interested in is how humanity would deal with such an achievment.

When man's lifespan was c.a. 30 years, did that seem like a long, full life to people living then?

What if our perception of time simply dilated to match the timescale of our lives? Minutes become seconds, days become hours, and months become days...is perception of time based on physical scale and the speed at which me move, or on the length of time you live?

Bourne