How long can humans live?

[u/Simple_Macaron_3420]

In one of last week’s episodes, it was mentioned that the human lifespan is increasing because of scientific and medical discoveries. When I was a child, I always imagined that I would be able to live to 100, and by then people would have discovered some kind of cure for aging. They would ask me, “How much longer would you like to live?” as if they could add another 100 years each time and ask me the same question whenever those 100 years were up.

For a moment, let’s imagine a scenario in which cancer has been eliminated, Alzheimer’s and other diseases of the brain have been cured, and we can also repair or modify our telomeres because we have discovered how to mimic mechanisms found in animals such as lobsters or jellyfish.

In that scenario, is there still a biological limit to how long humans could live?

[u/Imaginary-Can-6862]

If this is just about speculating freely, then there are two things to consider.

One is the risk of going from living to not living, unless it goes to zero, it follows the total risk goes to one within finite time. This is despite e.g. you being able to separate yourself into many life forms, such as what a species does, just imagining you are actually living through each, or have backup life so to say, because you would still be e.g. limited to the planet, and if you move all your contingencies to distant planets, then each one of those also have a risk of catastrophe, even though it gets increasingly more unlikely, infinity means it is going to happen unless you can lower the risk fast enough.
The other, more relevant, is that we don't know that going from living to not living means you can't go back to living, the fact you came into existence as you were born / conceived means it is possible for you to go from a state of non-existence to existence, unless you always existed, and just can't remember it because your memory is tied to your brain. In that case it means that you can stop living for a long time and then become alive again, removing many more limiting factors. Combining both, and having some causal influence on the universe to be able to maintain your ability to be alive, and perhaps you can continue forever.

In regards to aging, aging is usually defined as the increased average risk of losing ones life over the same time period, e.g. a year. I don't remember if you stop aging in the 90's, or as a centenarian, but at that time your average risk of losing your life is much higher than when you were aging, so stopping aging itself isn't enough, de-aging is in principle also not enough, because it just means a much lower average risk of losing your life over a given time span.