With some regularity I hear the claim that, with sufficient advances in medical science, people can live forever — become immortal. Clearly that’s nonsense.
Perhaps someday medical science will be able to halt and reverse the aging process in humans, to cure heart disease, cancer, and the other diseases that kill us, and thereby to grant people an indefinitely long life, without death from “natural causes.” But obviously an indefinitely long life is not the same thing as immortality.
Two things kill people besides medical problems: homicide and unintentional injuries. CDC reports that, in 2007, 18,361 U.S. residents (6.1 per 100,000 population) died by homicide. And 123,706 (41.0 per 100,000 population) died by unintentional injury. The fraction of people who die every year of non-medical causes, then, is 0.000471.
According to my geek friend Paul Hsieh, one can calculate average life expectancy simply by dividing one by the death probability, which in our case renders 2,123 years. Paul adds, “Of course, there’s a long ‘tail’ of some people who might live for” very much longer than that. Thus, the “half life” of the population — the time by which half the original population would be dead — would be a few hundred years less than the average, or 1,472 years. (Paul recommends the discussion at Wikipediafor details.)
No doubt a life span over two millennia is a very long time, but it is hardly immortality. Such a state obviously would dramatically impact our understanding of a “normal human life.” It would also replace the norm of expecting to die of natural causes with the expectation that all death would result from largely random and unexpected causes.
There are some variables with this. Obviously, not everybody is at the same risk of dying by unintentional injury or homicide. A drug-dealing extreme-sports fanatic is much more likely to die prematurely than, say, a fit librarian. And it’s possible for the human-caused (as opposed to medical) death rate to change over time within a society.
Then there’s the remote possibility of being able to “back up” one’s consciousness, say, by daily transmitting a large data packet to a backup site on Mars, such that a person could be regenerated even if his physical body died. Now we’re really talking far-out science fiction. But if you look at the rate of technological advances over the last hundred years, perhaps it’s not so crazy a scenario.
But even with very-long lifespans, death would remain a possibility, and therefore, an inevitability. You’d have to worry about wars, large-scale interstellar events, and so forth. If your backup gets destroyed (or there’s nobody around to access it) and you’re stuck in the middle of a brutal thermonuclear war, you’re pretty screwed.
Even the possibility of ending death by medical causes seems incredibly remote; the notion of backing up one’s consciousness far more so. So why should anybody alive today care?
To me, the real value of such speculation is to remind ourselves that everybody dies. Within Ayn Rand’s theory of ethics, this fact establishes life as the basic metaphysical alternative (to death) that gives rise to the entire phenomenon of value. In some sense it is our need to keep ourselves alive that gives rise to value as such. How that works out remains complicated and controversial, but it’s an important insight, I’m convinced.
I hardly expect to outlive Methuselah, though I’d like to live to be 120 in good health. I expect that might become fairly normal within the next century, provided politicians do not continue to muck up health care and the economy as a whole.
Paul Hsieh commented April 27, 2011 at 2:35 PM
It also means that working on reducing small risks might become far more important to future Methuselahs.
For instance, if wearing a certain safety harness while driving reduced your yearly rate of fatal injury from 0.0002 to 0.0001, it might effectively *double* your expected lifespan from 5,000 years to 10,000 years.
Andrew commented April 27, 2011 at 3:25 PM
What Paul added about the small risks! It comes up occasionally in speculative fiction (Lazarus Long’s prepared paranoia leaps to mind), and all the time in my own life ;P
I observe that I must be protecting like 10+ healthy lifespans in my moment-to-moment choices compared to the personal risk profiles I observe in ‘normal’ people. Actions >> words
Anthony commented April 27, 2011 at 3:51 PM
Presumably doctors will get better at fixing people who get assaulted or injured.
In fact, I assume the “fraction of people who die every year of non-medical causes” has gone down over time. But I guess I could be wrong.
Joshua J. commented April 28, 2011 at 10:05 PM
It is, of course, obvious that no one can literally live “forever”. No one believes this except theists. What “immortalists” believe is that people can live practically forever, for thousands, perhaps millions or billions of years (or longer, maybe).
Obviously, the longer lifetimes would require “uploads” of consciousness in order to be achieved, but given the enormous progress we’ve seen in just the last hundred years in science, I have no doubt such a thing will be possible in another couple thousand years.
As for why it’s important now: Biotechnology may very well extend the healthy lifespan of someone in their forties or even fifties by an extra 20 or 30 years (Aubrey de Grey estimates the likelihood of this at about 50%). If such a thing could be achieved, there would be an unimaginably large amount of money poured into medical research to fix disease and repair the damage of aging, because no one wants to die and all of a sudden living for a few centuries would be a realistic possibility for many (plus, think of all those people paying bucketfuls of cash to live longer, and with each advancement, they’ll be paying for it longer!). This would spur more development, and soon we will likely hit what is dubbed “actuarial escape velocity”, where our life expectancy increases by one year each year, so we never get statistically closer to death, and with an increased rate of advancement will retreat from it, indefinitely.
This, too, would spur more investment and research. I’m only 20, and I think there is a better than even chance I could live thousands of years. “Indefinite lifespans” as they are called seem an achievable goal within many of our lifetimes (certainly mine, haha), and that is why the whole idea is important. Just one more reason to want the government to get out of the way.