The idea of living forever simply does not add up, say scientists.
Researchers in the US applied mathematical rules to basic biological processes involved in ageing.
They discovered that the dream of immortality is destined to remain exactly that - nothing more than fantasy.
"Ageing is mathematically inevitable - like, seriously inevitable," says Professor Joanna Masel, from the University of Arizona.
"There's logically, theoretically, mathematically no way out."
Current theories leave open the possibility of eternal youth if the body could be taught how to eliminate poorly functioning "ageing" cells. One way of achieving this may be to encourage "survival of the fittest" cell competition.
However, nothing is ever that simple, Prof Masel and colleague Dr Paul Nelson point out.
Dr Nelson, also from the University of Arizona, says: "As you age, most of your cells are ratcheting down and losing function, and they stop growing as well.
"But some of your cells are growing like crazy.
"What we show is that this forms a double bind - a catch-22.
"If you get rid of those poorly functioning, sluggish cells, then that allows cancer cells to proliferate, and if you get rid of, or slow down, those cancer cells, then that allows sluggish cells to accumulate.
"So you're stuck between allowing these sluggish cells to accumulate or allowing cancer cells to proliferate, and if you do one you can't do the other.
"You can't do them both at the same time."
Writing in the journal Proceedings of the National Academy of Sciences, the researchers demonstrate mathematically that ageing is an "intrinsic property of being multicellular".
Prof Masel says: "It's no surprise that we're all going to die; lots of things are obvious because they're so familiar to us, but really, why is it that we age? We start to explain why.
"You might be able to slow down ageing but you can't stop it.
"We have a mathematical demonstration of why it's impossible to fix both problems.
"You can fix one problem but you're stuck with the other one.
"Things will get worse over time, in one of these two ways or both: Either all of your cells will continue to get more sluggish, or you'll get cancer.
"And the basic reason is that things break.
"It doesn't matter how much you try and stop them from breaking, you can't."
PA
