Average life expectancy has risen by 16 years since the national retirement age was set at 65. We asked health experts when they think people should stop working now.

In 1881, the conservative German Chancellor Otto von Bismarck, plagued by a rise in socialist ideology, proposed a national retirement benefit to appease the leftist masses. He set the retirement age at 70. Average life expectancy at the time? About 40 years.

Von Bismarck resigned shortly after the policy passed, but his legacy remained, and Germany’s retirement benefit (which was lowered to age 65 in 1916) became the model for many other nations. When President Roosevelt established the Social Security Act of 1935, 65 was similarly chosen as the national retirement age, despite the fact that less than 60 percent of American adults lived that long.

Which is all to say, the national retirement age in the U.S. and elsewhere has origins in a bit of political smoke and mirrors; it began as a symbolic offering, accessible only to the lucky citizens who managed to survive well into old age.

Today though, many more people live long enough to have access to a national retirement fund, often for years if not decades. Average life expectancy in the United States is 76, and in many European countries it’s even higher. The U.S. national retirement age — when you can start claiming full Social Security benefits — has crept up much more gradually, to 67 for people born after 1960.

In response, several countries — most notoriously France, where the retirement age is 62 and life expectancy is 82 — are debating raising the retirement age to try to offset the economic pressures of an aging population and the concern that national retirement benefits won’t be able to keep up for much longer.

From an economic standpoint, a later retirement age perhaps benefits everyone’s bottom line. But putting finances aside, what are the mental and physical implications of raising a national retirement age? We asked experts to weigh in.

One way to answer this question is to look at changes not in life span but in health-span — the number of years people are healthy and disability-free. Think of it as your work-span.

Gal Wettstein, a senior research economist at the Center for Retirement Research at Boston College, looked at age and potential for employment in a study about people’s working life expectancy. He found that Americans who are healthy at age 50 can expect to have roughly 23 more years free of disability, plus about eight years living with disability. That would suggest people’s maximum working life expectancy, on average, is age 73.

“There’s no doubt that life expectancy is longer, and also the ability to work has expanded,” Dr. Wettstein said. “Part of that is medical changes, and part of that is the nature of work has changed.” In 2020, roughly 45 percent of the American labor force worked in a knowledge-based field, such as management, business and finance, education and health care. In 1935, these types of professions accounted for just 6 percent of the workforce.

Dr. Pinchas Cohen, dean of the Leonard Davis School of Gerontology at the University of Southern California, agreed that, from a health standpoint for people in these fields, a retirement age under 65 “makes no sense.”

“Even 65 is a 20th century number,” he said.

For people working in knowledge-based jobs, a retirement age in the 70s is reasonable from a cognitive perspective, too, said Lisa Renzi-Hammond, director of the Institute of Gerontology at the University of Georgia. “Our cognitive faculties we’re able to maintain, usually, pretty well into our 70s,” she said. “If retirement age is set based on the capabilities or competence of employees, there’s absolutely no reason to have a retirement age in the 60s.”

Parts of the brain — most notably the prefrontal cortex, which is critical for executive functioning, attention and working memory — do start to lose volume as early as around age 45, but other areas are able to compensate, Dr. Renzi-Hammond said. And other aspects of cognition, such as crystallized intelligence (accumulated knowledge that can be applied to new situations) and social cognition (behaving appropriately in interpersonal interactions), continue to improve for decades.

Many of these cognitive processes are maintained and strengthened by staying in the work force. Consequently, some people decline mentally and physically when they stop working. One study even found that delaying retirement was associated with a decreased risk of death, regardless of health before retirement. Experts speculate that the losses of job-related physical activity and social interactions that come with leaving work are largely to blame for post-retirement declines.

National health and disability averages don’t tell the full story, though. While some people stay sharp and continue to work into their 80s, other jobs are more physically demanding and take a toll on people’s health.

“There are people who do manual labor where at age 65, they really cannot continue to do this very challenging work,” Dr. Cohen said. “Their need to retire needs to be respected.”

For these types of work, retirement can actually improve health outcomes, Dr. Renzi-Hammond said. “If you’re leaving a job that is physically bad for you, where you are getting terrible sleep and you’re constantly stressed out, then retirement is great for your health.”

Life span and health-span are also not consistent across race and gender, both because of the type of work certain demographics are more likely to take part in, and the toll chronic stress from discrimination takes on the body.

In his research, Dr. Wettstein found that, at age 50, Black men have a working life expectancy of approximately 17 years, while white women could continue working for 24 years. “There is an equity concern there, both on the life expectancy side, and also on the working-life expectancy side,” Dr. Wettstein said.

“We know that Black Americans, particularly, develop illness at earlier ages, live with more disabilities, die younger,” said Dr. Lisa Cooper, director of the Johns Hopkins Center for Health Equity. “So not allowing them to retire until they’re older means they’re just not going to benefit from” Social Security as much. This is also true for people from lower income brackets and those who work in physically intense jobs, she added.

As a result, Dr. Cooper said, “Raising the retirement age needs to be done with all of these issues in mind, because it’s not going to affect everyone the same.”

The initial intent for Social Security when it was established in 1935 was simply to sustain people once they could no longer physically work. But another way to think of federally funded retirement is that it should reward people with a few years of leisure.

“One of the areas that we don’t talk enough about is: What do people deserve?” Dr. Cohen said. “Is a few wonderful years when you’re still healthy — that you can do things and travel and so on — is that a national goal?”

In France, and likely elsewhere too, many would say yes.