Health & Medicine / Aging

A few years back, biodemographer Jay Olshansky called his friend Steve Austad, a gerontologist, after reading an outrageous quote attributed to Austad about aging. Olshansky, at the University of Illinois, and Austad, at the University of Idaho, have long shared an interest in the human life span. But they differ on some points. Austad had been quoted as saying that someone alive today could survive to the unprecedented age of 150.

Most students of human longevity agree that exercise, antioxidants, low-fat diets, and prostate exams will join forces with a battery of new techniques to extend the lives of seniors and improve their quality of life. But that amiable projection raises a tough question: If medical science were to eliminate geriatric infirmity and disease entirely, how long would the human body last? Is there some built-in expiration date for each member of our species beyond which no one will ever survive? If so, what is it, and why does it exist?

Demographics of the last two centuries seem to be on the side of soaring life spans. Worldwide, average life expectancy has increased from about 27 years to more than 65. In the United States, a person born in 1900 lived, on average, less than 50 years; now the average life span is 78. Japanese women, the longest-lived people ever known, now have a life expectancy of 85 at birth.

These unprecedented gains are reflected in the number of people surviving to extreme ages. The longest-lived human whose age has been unequivocally documented is Jeanne Louise Calment, a Frenchwoman who died six years ago at age 122. Although people of such advanced age are still rare, they’re becoming more commonplace by the minute. The United States now boasts a population of more than 40,000 people aged 100 and older. In 1950 there were only 2,300 centenarians in this country. James Vaupel of the Max Planck Institute for Demographic Research in Rostock, Germany, says the number of centenarians in many industrialized nations is doubling every decade.

Vaupel has shown that the maximum life expectancy among such countries has risen steadily by more than two years each decade since 1840. The increase is “so extraordinarily linear that it may be the most remarkable regularity of mass endeavor ever observed,” Vaupel wrote in a 2002 paper coauthored by Jim Oeppen of Cambridge University. If that pace continues, Vaupel maintains, the average life span in industrialized countries in 2150 will be 122.5, making 150-year-olds common.

Demographer Ronald Lee of the University of California at Berkeley says Vaupel’s analysis came as “a big surprise. We just did not expect to see a linear increase in life expectancy. It’s hard to resist extrapolating that line. That’s a 25-year gain every century.”

Still, Olshansky has reason to be skeptical. The astounding improvements in public health between 1900 and 1950, aided by such factors as refrigeration, sewage treatment, and safer working environments, produced many of the increases in life expectancy in the last century. The advances helped young people most of all by greatly reducing infectious and parasitic diseases that decimated infants and children. Each young life saved added decades to the raw numbers from which life-expectancy averages are drawn, since a person who survived childhood at the turn of the last century was likely to live decades more.

“Once you’ve accomplished that, you’ve accomplished your easy gain in life expectancy,” Olshansky says.

Around 1950, he says, the pattern reversed, and most medical gains helped prolong the lives of older people. Medical interventions headed off many ills of the aged, especially the number one killer: heart disease. But saving those who are living out the last years of their lives adds only a few months or years to the actuarial tables. Olshansky therefore believes that even major advances in geriatric care won’t push life expectancy much past 85—at least not in the lifetime of anyone alive right now.

“There are no lifestyle changes, surgical procedures, vitamins, antioxidants, hormones, or techniques of genetic engineering available today with the capacity to repeat the gains in life expectancy that were achieved during the 20th century,” he and his collaborator Bruce Carnes, of the University of Chicago, have declared.

“Will the maximum human life span increase in the future? Probably,” Olshansky says. “It’s possible someone might make it to 130. But to go another 20 years? I don’t see it happening.”

Vaupel says Olshansky belongs to “a sorry saga of distinguished people” who postulate that some maximum age will never be exceeded, only to see it exceeded within five to seven years. “If life expectancy were close to reaching a maximum, then the increase in the record expectation of life should be slowing,” he and Oeppen wrote. “It is not.”

When Vaupel’s daughter was born in 1984, he claimed often and in writing that she would live to see 100. Olshansky’s daughter was also born in 1984. While wishing her no ill, he says she most likely won’t live to be 100. “Purely mathematical extrapolation of a biological phenomenon is inherently dangerous,” he warns. And so it has gone, with Vaupel and Olshansky trading fire in the scientific literature for decades.