The Future of Humanity, Part 3: A Longer Life

Imagine what it would be like to run into an old friend you hadn’t seen in centuries. How would it feel to have memories as old as the Mongol Empire? Or to hold your great-great-great-great-great-great grandchild? These are just a few of the corridors to explore when pondering a tenfold increase in lifespan. Longer lives would also have implications for interstellar travel. The average distance between stars in our galaxy is about five light years. The concept of crewed spacecraft averaging one-tenth light speed is not far fetched, but even this achievement would still mean 50-year journeys to reach the nearest exoplanets. If people expected to live for centuries, such a voyage may seem much more palatable: an intermission between one’s Earth life and Proxima b life!

It’s no secret that the average life expectancy of human beings has increased over time. In fact it has mainly risen only in the last two centuries, having hovered near 35 years for most of human history before then. This higher life expectancy is often misinterpreted as meaning people are able to live to older ages than they could in the past. This is not true. We are simply less likely to die young. Before the modern era roughly one quarter of all people died before the age of one, and another quarter did not make it to fifteen. In an odd way aging was to outrun death, since surviving into adulthood meant entering a relatively safe period of your life.

But then as now old age eventually takes its toll on our health. No matter how careful we are, the kinds of injuries and diseases that lead to death become harder to avoid. The theoretical upper limit on a human lifespan, which scientists estimate is about 125 years, is the same now as it was at any other time in human history. But will it always be the same? If we can somehow stop or slow the processes that cause aging, we would not only increase this upper bound, but also make us likelier to reach it.

The prospect of greatly increasing lifespans is often met with skepticism and even repulsion. The skepticism is perhaps understandable. Death is and always has been a certainty. Everyone dies, it’s just a matter of when. Moreover, death is final. So while you may avoid or at least recover from disease and injury, death affords no such possibility. But the mistake here is to think prolonging life is cheating death. It’s not. We’re not talking about becoming immortal. Instead it’s about cheating aging. If we do manage to greatly extend lifespans, it will remain an unfortunate fact that you can still die young. Slowing down the metabolic processes that cause aging will not help you if you get hit by a train. In this case dying young would be all the more tragic, given how much more life was robbed of you.

Aging is such a certainty that we rarely consider it a solvable problem. Our bodies are constantly replacing old cells with new ones. We can heal from all but the most serious wounds. As long as we avoid catastrophic injury, eat and sleep well, why should we not be able to maintain this process of regeneration indefinitely? According to aging researcher Aubrey de Grey (no relation to Dorian Gray) there are only seven processes known to cause aging, and since no more have been discovered since the early 1980s it’s likely that these are the only ones. These processes involve DNA mutations, loss of stem cells, the buildup of botched proteins in and around cells, and the accumulation of functionless cells. These changes lead to the familiar symptoms of aging and leave us less able to ward off diseases. While the technology to reverse these changes is still a ways off, some progress has been made. De Grey has predicted that there may be people now alive that will live to a thousand years old. This may be a bit optimistic, but he is not alone in the view that vastly longer lifespans could eventually be possible.

Way too many times I’ve heard people dismiss the idea of a longer life as not just unlikely but actually undesirable. “Who would want to live that long?” “I want to live to the age of 75 and that’s it.” “Think of how boring it would be to live for hundreds of years!” Statements like these are maddening. Of course you would want to live longer, just as you want to continue living right at this moment. And why would these extra years be any more boring than the ones you’re living right now? Get a hobby! Make friends! Life is fun. The notion that you wouldn’t want ten times more of it evaporates the moment you give any serious thought.

However, there are some reasons to be cautious about extending lifespans. I can think of three possible drawbacks. As with many other technological and medical advances, it’s probable that extended lifespans will not be equitably distributed, at least at first. We don’t want a world where the haves live ten times longer than the have-nots. It’s also possible that as lives get longer the rate of social and scientific progress could decline. Unlike in the past, most people today think slavery is wrong, and that the Earth orbits the Sun. But such changes in our collective outlook have less to do with people changing their minds and more to do with old minds being replaced by new ones. If the same minds are around much longer than they used to we would want to make sure they are flexible enough to keep up with the Zeitgeist.

Both of these potential issues are at least in theory preventable with proper planning and attention. The third problem we may encounter as lifespans increase is the added strain on Earth’s space and resources, since fewer deaths would lead to a population boom. Other than imposing limits on childbirth, which has its own major drawbacks, the only other reasonable solution would be for humanity to reach beyond Earth.

So while drastic increases in lifespan should be approached with due consideration of the side effects, it would be pretty damn cool. Callisto, here we come!