Laura Carstensen: Long Life in the 21st Century

By Christine VanDeVelde Luskin, Writer and Bing Alumni Parent

Professor Laura Carstensen

Professor Laura Carstensen

Next time you visit Bing Nursery School, look around at the boy building a tower of blocks in East room and the girl laughing on the tire swing in the redwood grove and the toddlers gathered for story time. They will likely be among the first centenarians of the 22nd century.

Today, the majority of children who are born in developed regions of the world have the opportunity to grow old—a change unprecedented in the history of humankind. That’s because in the 20th century, life expectancy nearly doubled in industrialized nations around the world. A new stage in life has been created—old age—and we’re only beginning to come to terms with the implications.

On May 6th, Stanford University Professor of Psychology and founder of the Stanford Center on Longevity, Laura Carstensen, presented to the Bing community in the 2009 Distinguished Lecture her overview of long life in the 21st century and beyond—how we got the fabulous gift of an extra 30 years for the average person, and what we need to do now in science and technology to ensure these added years are good years.

Best known for the development of socioemotional selectivity theory, which posits that the perception of time plays a fundamental role in the selection and pursuit of social goals, Carstensen founded the Center on Longevity to combine such research with swift entrepreneurial action and to deliver products and policy that will improve the quality of life for an aging population.

But before considering the question of creating a world that is going to allow today’s children to become healthy, happy, fit, independent and secure as they live long lives into the next century, it’s necessary to understand how we arrived here.

For most of human history, life expectancy hovered at around 20 years. That’s barely enough time to reproduce and then stay around long enough to insure offspring would survive. Things were touch-and-go for a long time for the survival of our species.

Life was extended by natural evolution. Longer-lived people were selectively advantaged, so life expectancy inched up in the way evolution acts—that is, very, very slowly. By the mid-1800s, life expectancy in much of the developed world hovered around the mid-30s. By 1900, in the United States, life expectancy was 47. But by the end of the 20th century, life expectancy had risen to 77—thirty years in just a century! At the same time that life expectancy was rising, fertility rates were falling. On average, the number of children born to American women fell from 4.2 in 1900 to 2.1.

These two factors—longer life and decreased fertility—created an unprecedented change in the distribution of age in the population. In 1900, about 4 percent of the U.S. population was over 65. Today it is about 13 percent. By 2030, 22 percent of the population in the United States will be over 65.

But why are people living longer lives? The demographic changes that are occurring in the United States have nothing to do with a fountain of youth. In fact, the story of how society launched into this era of long life doesn’t begin with a discussion about older people at all. It begins with a story about babies.

The dramatic increase in life expectancy in the 20th century occurred not because old people lived longer, but largely because fewer people died when they were young. In 1900, 25 percent of the babies born in this country died before they reached the age of 5. Many more were orphaned by the time they reached 18, and many more were permanently disabled because of chronic diseases. Remember polio? Life was very, very hard for young people.

But medicine only gets some of the credit for these changes—for dealing with the spread and impact of disease at a fundamental level. And natural evolution had nothing to do with the changes seen in the 20th century. The true story is much more complicated and interesting.

In fact, garbage collectors should get as much credit as doctors for the 20th century’s increase in life expectancy. Because the earliest and largest gains in average life expectancy came about because of community-wide efforts to improve sanitation and the safety of the food supply.

There were many changes: Waterways were purified, food-borne pathogens were identified, and surveillance of the food supply was implemented. Governments in Europe and the United States built vitamins and nutritional supplements into the food supply that improved the health of young people, and these food-fortification programs nearly eliminated major nutritional deficiencies like rickets, goiter and pellagra. After electricity came into common use, there was refrigeration. Heating and cooling systems were incorporated into daily life, which, again, improved people’s chances at long life. But it was access to these technologies—as much as their discovery—that led to these changes. For example, if it had only been the wealthy who had refrigerators, the safety of the food supply in the entire population would have remained precarious, even for the wealthy.

The long life people are enjoying right now is really an amazing triumph of culture. “Culture” doesn’t just connote the foods people eat and the languages spoken, but the way that people transmit knowledge across generations, the social practices that are encouraged, and the collective efforts of people to improve the well-being of entire populations. Nobel Laureate economist Bob Fogel of the University of Chicago describes what happened in the 20th century as “techno-physio evolution”—that is, evolution not by natural selection, but by changes in societies and culture. In other words, culture operated on the individual, influencing human biological capacities.

At the same time that these changes in public health were occurring and fertility rates were falling, societies were also increasing the investment made in young children through initiatives such as public education and child labor laws. Develop-mental science was identifying how children think, considering how they best learn and the optimal way to frame information for them. So today the world is exquisitely attuned to the needs of the very young. And this world that was developed to save the lives of the youngest among us is also responsible for long life.

The result is that we are at a point in human history where very soon there are going to be more people in the developed world over 60 than under 15. The shape of families is changing, with four, five, and even conceivably six generations alive at the same time—again, something unprecedented in the history of humankind.

The implications of these changes are only beginning to be contemplated. Primarily, the public is voicing concern—that so many old people in a population will take from the young and leave fewer resources for schools and children, that aging societies will break the bank on health care and retirement, forcing young people to bear undue burdens. There is fear that eventually society and individuals will be forced to make stark choices between providing support for children and their parents, and the aging. It’s common to hear among policymakers that a crisis is on the horizon that will cripple society.

There are serious problems with aging as we know it. To the extent that societies are comprised of people who are cognitively impaired and suffering from serious diseases, it will threaten the future. But the remarkably good news is, on average, people are getting healthier at the same time as, on average, they are getting older. In the 1980s, when it became possible to accurately predict what the population was going to look like, there was concern that any added years would all be sick years. So people would live longer but be sick longer. That hasn’t come to pass. In the last 50 years, each elderly cohort that has arrived at age 65 has been healthier than the preceding one.

But there is some bad news. Discrepancies by social class are profound and the gap is widening. There will be two old ages: one for the wealthy and educated, and one for the disadvantaged. “The Americans’ Changing Lives Study” by James House of the University of Michigan showed that more than 90 percent of people over age 60 who have 16 or more years of education report no functional limitation. Even at age 75, there is not much change: 80 percent of this group shows no functional limitation. But for those who don’t graduate from high school, there is a decline in health that begins at age 30 and progresses steadily downward throughout adulthood.

Crisis is usually the catalyst for scientific breakthroughs. So to the extent that there is fear that a crisis looms because of an aging population that can be used to direct energy and attention to solutions. If the same ingenuity and commitment that was used to improve the lives of children in the last century can be used to improve the health and well-being of people 50 and older, then longer-lived populations could inspire major breakthroughs in science and technology that will improve life at all ages. Science and technology got the population here, and science and technology will lead the way forward again, transforming human aging from an object of fear and loathing to a goal that people aspire to.

The work of Carstensen and her colleagues at the Center on Longevity will be part of the answer. Just as 60 years ago researchers and scientists were studying children’s minds and how they access information, today, the quest is to understand the ways that information can best be presented to and processed by older learners.

Although it doesn’t disable people, cognitive decline is a major public health problem. Setting aside dementia and Alzheimer’s disease, there is clearly general deterioration in memory and comprehension that occurs with age. While such deterioration is offset by increases in knowledge, cognitive decline is an important area of inquiry in the quest to improve the quality of longer lives. Among the questions being explored at the Center on Longevity are whether increased knowledge can be used to offset decline in the speed of processing information and how information can be framed so that older individuals retain it better.

Carstensen’s theory of socioemotional selectivity—holding that people set goals in temporal contexts, and those contexts change as we get older—is the basis for much of the inquiry into the psychology of the aging. When the future is perceived as expansive and open-ended, when mortality or endings aren’t contemplated, individuals feel like they have all the time in the world. Under those conditions, people are motivated to collect things: people, information, knowledge. People are willing to take risks because they’re acquiring knowledge and banking it. Even if it’s not important now, they reason to themselves, it could become important down the road.

But as people begin to see the future as less open-ended and more constrained, they are motivated to achieve emotional balance, placing more value on experiencing satisfying relationships and other pursuits. In part, that’s because these goals are realized in the doing, in the present. So as people age, goals change, and they care more about emotional experiences than gaining information.

One of Carstensen’s key findings is that as people age, there is a preference for positive information. In a study in which subjects were shown positive, negative and neutral images and asked to recall as many as possible, it was found that young adults remembered exactly the same number of positive and negative images; middle-aged people remembered more positive images than negative; and older individuals had a significant response to positive information, remembering far more positive images than negative or neutral. This bias—not any lack of basic mental competence—may explain why older people can be more susceptible to swindles and scams.

So Carstensen and her colleagues then set out to see if the preference for positive information could be circumvented by re-framing goals. Further studies established that when the goal is changed from remembering as many as possible to being as accurate as possible, the difference across ages was eliminated entirely. This is one of the many ways that communication and learning in older age is being studied so that cognitive performance can be enhanced and the quality of life continues to improve as people age.

It’s interesting that younger people often think the psychology of older people must teeter between terror and depression as they age. It’s actually the opposite. Older people’s mental health is better than younger people’s—there is less depression, less anxiety, less incidence of all psychiatric disease other than dementia. In some sense that’s because older people are relieved of the burden of the future. There are all sorts of “what ifs” in life, and humans are not good at dealing with “what ifs” emotionally. Humans are good at adapting to the cards they’ve been dealt once they’re known, but it’s psychologically difficult to not yet know what those cards are. So the best years actually do seem, for most people, to come later.

And the best news is that today the potential of science and technology to further improve our later years—both in small ways and large—is breathtaking. Engineers at Stanford are developing shoes that slow the progression of osteoarthritis. There are new medical fields: for example, regenerative medicine—the possibility of growing new tissues from an individual’s own cells—that didn’t exist 20 years ago. Economists like George Shultz and John Shoven are coming up with win-win solutions to solve Social Security’s financing problems so that individuals will continue to work through the golden years. Dr. Alan Garber is working on finding realistic, fair ways to move forward with health-care reform. Much of this work is being done with the Stanford Center on Longevity. Going forward, lessons from the history of how long life was achieved in the last century can be used to develop technology and policy in response to the demographic changes underway in the United States, innovation that will benefit all of us and our children.

Laura L. Carstensen is a professor of psychology at Stanford University, Fairleigh S. Dickinson Jr. Professor in Public Policy, and founding director of the Stanford Center on Longevity. Carstensen is best known for socioemotional selectivity theory, a lifespan theory of motivation. She received her B.S. from the University of Rochester and her Ph.D. in Clinical Psychology from West Virginia University. She is also the grandmother of Bing graduate Evan Pagano and current student Jane Pagano.