The Brevity of Human Life

Time Flies, Whether You're Having Fun or Not

The tube worms will miss you.

By about the time they reach early middle age, most people not in the midst of extreme and irremediable suffering begin to develop a gradually deepening conviction that their lives are progressing quickly; that even the full human lifespan they hope to complete is distressingly brief. But not until reaching the very end of their days do they realize how right they really are.

01 “Life is short.” One hears this trite, media-amplified mantra all the time, expressed knowingly as a warning and a call to action, or as a vaguely cynical and self-indulgent justification for engaging in risky behavior, seeking instant gratification, and “living in the moment”. There’s a double irony here. People who most often declare that life is short — typically young and healthy adults — have less appreciation of this sobering fact than others who, due to age or infirmity, are more directly confronted by it; and they have a greater tendency to make correspondingly short-sighted decisions that reduce the duration of their fleeting existence even further.

02 Part of the difficulty in thinking about the extent of our lives is that even as we come to the conclusion that they are all too brief, we continue to regard those who make it past the average human life expectancy as having had long lives. “Long”, of course, is a relative term; but in this context it can be taken to mean something close to the maximum number of years a person could reasonably hope to forestall death during the era in which they lived.

03 Today, in the United States, the average life expectancy at birth is almost 80 years, which dovetails with what we presently believe to be a long life. But at the time of America’s founding, the average life expectancy was about half of what it is now. In that period, factoring out the skewing effects of high infant mortality, a long life for someone who reached adulthood was about 60 years (although some people lived considerably longer). If we go all the way back to the onset of anatomically modern humans two or three hundred millennia ago, the average life expectancy was no more than about 30 years. This could be thought of as the “natural” and most evolutionarily optimal lifespan of Homo sapiens — long enough to reproduce, form lasting social bonds, and care for offspring, but not so long as to continue to compete for scarce resources past sexual maturity and outlive usefulness to succeeding generations.

04 Because our current lifespans are twice as long as they were a few centuries ago, one might say that, relative to our forebears, we now have an entire “second life” to enjoy (or endure), on top of what we would have possessed in earlier times. But unless our lives are utterly miserable, even that doesn’t seem like nearly enough. Even people who have no desire to live forever would gladly accept many more years of life, if they had at least a fighting chance of staying healthy enough to derive some benefit from them. Once we get used to living, even with all of its difficult challenges, most of us want to go on living … and on, and on, and on. It’s all we know — all we ever can know. Yet we seem to reach our end before we’ve barely begun.

05 Worse still, our limited time on Earth not only passes rapidly, but it actually seems to accelerate as we get older. Some speculate that this is because the older we get, each completed year comes to represent a smaller and smaller fraction of the total number we have lived. Others suggest it’s because older people tend to have fewer significant personal milestones to mark the time and prevent it from becoming a nondescript blur of repetitive, mundane events. Whatever the reason, it only adds to the growing angst we feel as we pass the prime of our lives and enter middle age, hurtling toward our unavoidable demise.

06 The situation is all the more galling when we consider the lengthy lifespans of some other, “inferior” biological entities. Perhaps the most well-known long-lived animals are giant tortoises, which have an average lifespan of over 100 years, with some individuals living beyond 175 years. But that’s exceeded by Greenland sharks (200-300 years), the tube worm species Escarpia laminata (300-plus years), and ocean quahog clams (up to 500 years). None of those hardy creatures can compete with glass sponges, which are estimated to live for over 10,000 years, a feat equaled or surpassed by several types of trees and plants. At the extreme end of the longevity scale, certain varieties of jellyfish and regenerative hydra are thought to be effectively immortal. By contrast, the oldest person ever documented lived a mere 122 years. That is how much nature (or God, if you prefer) favors human beings.

07 There are a great many misfortunes associated with our truncated lives, but three particularly prominent ones come to mind.

08 First, we are unable to realize our full human potential. Even if we hang on to 100, there isn’t even close to enough time to do and experience everything we want; to be everything we could be. This is especially true given that the first two decades of such a centenarian life would be devoted to achieving maturity and learning how to live in the world, and the last two decades would be diminished, at least to some extent, by physical and/or mental decline. Assuming good health during the remainder, that leaves, at best, about 60 years to robustly engage in adult life activities, to the extent surrounding political, social, and economic conditions allow. We might think that a lot can be done in those 60 years, but that’s only because we’re used to setting our expectations to match the limited time we have available. 60 years, frankly, is nothing. For a third of that time, we’re not even conscious; and for about another third, we’re performing all the mindless tasks that modern life requires. So in our hypothetical century of being, we’re effectively left with as little as 20 years of “quality” time to actively pursue the goals and endeavors that are important to us, which is patently insufficient. Even what we might regard as the fullest, richest, most accomplished lives barely scratch the surface of what is possible. We have a chance to try a few things, chalk up a small number of successes and failures, and that’s it.

09 Second, a key mistake or serious misfortune in a person’s early years can derail their entire future. There often simply isn’t enough time to fully recover from such altering events as a bad upbringing, a drug addiction, a poor career choice, a failed marriage, a financial disaster, an incapacitating disease, or a criminal incarceration. All of these things can be overcome, of course; but a substantial portion of the person’s peak years may be adversely impacted, so much so that they feel like they’ve been irretrievably lost; and the negative after-effects may continue to reverberate for the rest of the person’s life. If instead we lived for, say, a thousand years, we’d have a much greater margin for error, and the price of taking a wrong turn would not be nearly so high.

10 Third, our connection to the past, and our interest in the future, is sharply curtailed. We don’t live long enough to learn much from personal experience or directly acquire a great deal of historical perspective. We’re prone to engage in short-term thinking, rather than taking the long view. And we can’t easily focus our attention on critical but slowly evolving threats like climate change that won’t fully materialize within our own short lifetimes. Some believe that affinity for younger members of society — or, more specifically, for one’s own children (and grandchildren, and great-grandchildren, etc.) — can change this mindset by expanding the scope of our concerns beyond our own lives, but this only goes so far. Parents as well as non-parents are creating and leaving behind massive problems for ensuing generations to solve (if they can). No matter who else may be affected, it’s hard to care about something — good or bad — that won’t happen until after you’re dead; after you literally no longer exist. As far as you are concerned, it will never happen. From your inherently self-centered standpoint, when you vanish, the universe, and everyone in it, will vanish with you.

11 Because of these dispiriting realities, most people — even those who say that life is short — choose to act as if they’re going to live forever (see Article 4). If they manage to attain whatever society currently deems to be a “ripe old age” with minimal trauma and a few happy memories, they’ll then try to convince themselves that they got their due; that they had a good run; that they couldn’t ask for anything more. They want to feel satisfied, and maybe, in some sense, they will. But their lives passed in an instant. And the tube worms live on.