In Greek mythology, Tiresias, the blind seer of Thebes, lived beyond 600 years. In the Bible, Noah lived to be 950. And in Chinese legend, Peng Zu was believed to have lived for over 800 years during the Yin Dynasty.
We associate these ancient mythical figures with wisdom, an omniscience that is a consequence of their longevity. But as science enables humans in today's world to live longer, how do we assess the value of years we weren't otherwise prepared to live out?
In a quest for answers and a greater understanding of the meaning of a life that extends 30, 40, or 50 years longer than usual, we sat down with Shelly Kagan, the Clark Professor of Philosophy at Yale University. He says living longer means fundamentally rethinking nearly every set of social structures that help us to define who we are on this Earth.
"Instead of living to an average of 80, if people suddenly lived to 150, that would double the population, which would mean we don't have room for everybody," says Kagan. "That implies that we would then have to cut back on the number of children that people have. Right away that poses families in different directions from the ones we're used to. It leaves the question of what happens to the parents. Instead of having 20 years-plus of raising children in the house, we would have decades—really 50 or more years—in which we were still in prime health, at least that's what we're imaging, but our children have left the home."
Kagan says that for many, the central project of life revolves around family and raising children. With a longer lifespan, the process of raising children would seem relatively short—a period that passes as quick as high school. When taking the central life project of parenting out of life's equation, Kagan asks: What would we have as a replacement?
"Does the role of being a grandparent become a more significant one?" he asks. "Does the role of becoming a great-grandparent, or a great-great-grandparent–a role that doesn't even exist now for all practical purposes—does that become significant? What does that look like? One possibility is that extended families across many generations might come to the fore. But, of course, a completely different possibility is that family recedes from importance and we won't have deep family connections."
To be frank, Kagan says that humans cannot simply add 50 or 80 years to the average lifespan and believe that it will fit well with life as we currently know it. For much of human history, people have looked to the afterlife as way to "survive death" so they can continue living in one way or another, says Kagan. With a lifespan that could stretch for centuries, would the value we place on existence have a new meaning?
"If you imagine life going on longer, where do the extra years fall in terms of our life story?" asks Kagan. "Do we imagine the extra 30 or 40 years coming after we've retired? That's a difficulty right away because most people currently don't save enough money for a retirement, let alone a retirement that is two, three or four times as long. If instead you imagine the extra years coming during our working years, then which kind of jobs are going to be sufficiently interesting to sustain our interests for 80, 90 or 100 years? Or instead do we imagine that people will, at a certain point change careers, perhaps at the point where we would normally retire? But how is that going to work—who at the age of 60, 70 or 80 is going to want to start over at the lowest rung in their new chosen profession?"
Aside from the ways achievement milestones like parenting or careers would fit into a 150 year lifespan, Kagan says there are larger ethical and moral considerations to be had with a lengthening life. To aid this longer life span, Kagan says that technology could presumably provide deteriorating organs with things like synthetic livers or lungs—allowing humans to live for centuries or more. But at a certain point, would technology as a means to extend life distort the fundamental concept of being human?
"The human brain, like every organ, would eventually wear out," he says. "Imagine that the scenario is that when that stage is approaching, we upload the human personality of the given individual onto some computer chip or synthetic brain so that all of your memories, desires, beliefs, goals and ambitions are uploaded onto this chip. That chip would be then placed into a new synthetic brain, and that offers a scenario for which, conceivably, we might continue to live. But now we have to face the philosophical question: Is that still you?"
While humans may change from the age of 20 to 30, 40, 50 and beyond, Kagan says many people believe that they are fundamentally the same person who has merely persisted and survived through these changes.
"If we have the person with the brain copy or the duplicate, is that me—am I surviving the change of brain or is that rather simply a kind of xerox of me?" asks Kagan. "We have to turn strictly to philosophical speculation and metaphysics to face the question of, 'What kind of changes can I survive? How long can I live and still have it be, strictly speaking, me?'"