Maximum adult lifespan: Debate over how long humans can live.

What’s the Longest Lifespan I Could Have?

What’s the Longest Lifespan I Could Have?

Why we live so long.
Sept. 12 2013 5:41 AM

Just How Long Can People Live?

It’s one of the juiciest debates in science.

(Continued from Page 1)

Antibiotics are the lifesavers that are most familiar to us. When I asked my acquaintances why they weren’t dead yet, the most common stories involved infections that had been cured by antibiotics. Today we’re publishing some of the best #NotDeadYet stories that people tweeted or emailed to us over the past week. Many of you alive today would have been vanquished by bacteria in previous eras.

The public health interventions that protect children from infectious disease continue to echo throughout their lifespan. People who reach old age today are stronger and healthier than earlier generations, partly because they weren’t weakened in childhood by repeated infections. As more people live to old age, they have more time to develop diseases of aging, the most devastating of which is dementia. But taking age into account, the rate of dementia seems to be falling, probably because of improved overall health.

Life expectancy can make sudden jumps even in older populations in response to social conditions. Before the reunification of Germany, retirees living in the former East Germany had much lower life expectancies than their cousins in the West. After reunification, they started living much longer—even people in their 80s and 90s had years added to their lives.

People with more years of education live longer, and the gap is widening between people who didn’t graduate high school and those who have college degrees. That may not be surprising since the well-educated are also wealthier on average and have safer jobs and better access to health care. But a few studies have found that education in itself prolongs life; it seems to allow people to manage chronic diseases better, handle stress, and make better judgments. The proportion of the population with some college education has been growing, and that may pay off in better long-term health outcomes.

It’s all connected, of course—the reason we live longer today is that we are living in an entirely different world than the one people inhabited at the end of the 19th century. It’s less nasty, less brutish, and less short. One final reason we’re living longer is that we have less exposure to the most heart-breaking risk factor for death: bereavement. In other words, we are living longer because our loved ones are living longer, and thus we are less likely to be sunk in grief than at any time in human history.


* * *

So what’s next? What are the little things that could make our average life expectancy jump again? Some of them sound simple but really aren’t. “The biggest low-hanging fruit is smoking,” says medical historian David Jones of Harvard. “But is it really low-hanging?” About half of the population smoked in the mid-20th century. That rate dropped steadily until the latter part of the century, but it seems to have plateaued (although a recent gruesome ad campaign had promising results). About 20 percent of the population smokes, and it may be very difficult to get the remaining holdouts to quit.

Obesity is the other major risk factor for heart disease, cancer, diabetes, and any number of other causes of death. The obesity rate climbed so much in the past few decades that S. Jay Olshansky, a longevity researcher at the University of Illinois–Chicago, and his colleagues estimate that obesity could swamp the effects of reduced smoking on average life expectancy.

The most disturbing fact about life expectancy in the United States today is that African-Americans live about four years fewer on average than whites. The good news is that the gap has been narrowing. This disparity has been seen as a matter of social justice, but as Jones points out, there’s also a major gap in life expectancy between males and females. “I can expect to live five years less than my wife,” he says. “To me, this feels totally unfair.” We tend to think of this difference as something biological and immutable, but finding ways to help men live as long as women would go a long way toward improving life expectancy and making the world a less sorrowful place.

The United States could learn a lot from other developed countries. Our life expectancy is much shorter than it should be considering how wealthy we are. By some estimates, we’re 40 years behind other countries in terms of advancing life expectancy. The National Academy of Sciences took a hard look at what we’re doing wrong and identified nine things that set the United States apart from other countries, including drug and alcohol use, HIV and AIDS, adolescent pregnancy, and injuries and homicide. The Centers for Disease Control and Prevention calls many of these problems “winnable battles.”

* * *

One of the most fascinating debates in life science these days is between Olshansky and James Vaupel of the Max Planck Institute for Demographic Research in Rostock, Germany. They disagree fundamentally about whether and how average life expectancy will increase in the future, and they’ve been arguing about it for 20 years. Olshansky, a lovely guy, takes what at first sounds like the pessimistic view. He says the public health measures that raised life expectancy so dramatically from the late 1800s to today have done about as much as they can. We now have a much older population, dying of age-related diseases, and any improvements in treatment will add only incrementally to average life expectancy, and with vanishing returns. He explains his point of view in this charming animated video.

Video is courtesy of Project M.

On the other side of the ring is Vaupel, who says that people are living longer and healthier lives all the time and there is no necessary end in sight. His message is cheerier, but he takes the debate very seriously; he won’t attend conferences where Olshansky is present. His charts are heartening; he takes the records of the longest-lived people in the longest-lived countries for each year and shows that maximum lifespan has been zooming up linearly from 1800 to today. One wants to mentally extend the line into all of our foreseeable futures.

Olshansky says the only way to make major improvements in life expectancy is to find new ways to prevent and treat the diseases of aging. And the most efficient way to do that is to delay the process of aging itself. That’s something that some people already do—somehow. Olshansky says, “The study of the genetics of long-lived people, I think, is going to be the breakthrough technology.” Scientists can now easily extend lifespan in flies, worms, and mice, and there’s a lot of exciting research on genetic pathways in humans that might slow down the aging process and presumably protect us from the age-related diseases that kill most people today. “The secret to longer lives is contained in our own genomes,” Olshansky says.

Predictions about medical breakthroughs are notoriously optimistic, of course. When the human genome was sequenced, people predicted personalized medical interventions in a decade. That was 12 years ago. Richard Nixon’s war on cancer has yet to be won. So while you’re waiting, do what you can. Eat right, exercise. Drive safely. Don’t smoke or play with fire. Get that mole looked at. Are you sitting in front of a computer screen now? Stand up and stretch, do some lunges, we won’t laugh. Here’s to your health and long life.

Read the rest of Laura Helmuth's series on longevity.