Leonard Hayflick, who discovered why no one lives forever, has died at 96

Leonard Hayflick, the biomedical researcher who discovered that normal cells can divide only a certain number of times — a limitation on human lifespan that frustrated would-be immortals everywhere — died Aug. 1 at his home in Sea Ranch, Calif., at age 96.

His son, Joel Hayflick, said the cause was pancreatic cancer.

Like many great scientific discoveries, Dr. Hayflick’s discoveries came about somewhat by accident. As a adolescent scientist in the early 1960s at the Wistar Institute, a research organization at the University of Pennsylvania, he was trying to develop robust embryonic cell lines to investigate whether viruses could cause certain types of cancer.

He and his colleague, Paul Moorhead, soon noticed that somatic—or nonreproductive—cells go through a phase of division, dividing 40 to 60 times before settling into a state he called senescence.

As senescent cells accumulate, he said, the body itself begins to age and decline. The only cells that don’t age, he added, are cancer cells.

He said that because of the workings of the cellular clock, no amount of diet, exercise or genetic intervention will cause the human species to live longer than about 125 years.

The discovery, which the Nobel Prize-winning virologist Macfarlane Burnet later called the Hayflick limit, contradicts everything scientists believed about cells and ageing — most notably the idea that cells themselves are immortal and that ageing is the result of external factors such as disease, diet and sunlight.

Other researchers later discovered the mechanisms behind the Hayflick limit: When cells divide, they make copies of a strand of DNA, but the ends of each copy, called telomeres, are slightly shorter than the last. Eventually, the telomere runs out, and the cell stops dividing.

Dr. Hayflick made other significant contributions to science. He developed a particularly viable cell line, WI-38, which has been used for decades to produce vaccines. He also discovered that walking pneumonia, unlike ordinary pneumonia, is caused not by a virus but by a type of mycoplasma, the smallest form of free-living organism.

But it was his work on aging that established his legacy. Dr. Hayflick was an outspoken critic of those who thought they could discover a science of eternal life; he considered the idea an illusion, and the pursuit of it a folly, if not a complete fraud.

“Discovering ways to extend human life is the second oldest profession in the world, and maybe even the first” he said in a 2011 interview with the medical journal The Lancet“People are going to the bank right now with huge sums of money that they’ve managed to get by convincing others that they’ve found a way to extend your life or make you immortal.”

Leonard Hayflick was born on May 20, 1928, in Philadelphia, Pennsylvania, to Nathan Hayflick, a denture maker, and Edna (Silver) Hayflick, who worked in her father’s practice.

He enrolled at the University of Pennsylvania but took three years off to serve in the Army. He graduated with a degree in microbiology in 1951 and earned a Ph.D. in chemistry and microbiology five years later.

After two years as a postdoctoral fellow at the University of Texas Medical Branch at Galveston, he returned to Penn and the Wistar Institute, where he made many of his most significant discoveries. He continued this work at Stanford University in 1968.

There was a problem, though. The National Institutes of Health had funded research on the WI-38 cell line but refused to fund its distribution, even when other researchers requested samples. Dr. Hayflick set up a company to process orders, charged a minimal shipping fee, and banked the proceeds until the ownership issue was resolved.

But in a private report released to the media, the NIH accused Dr. Hayflick of theft. He sued the institute, accusing him of invasion of privacy and reputational damage, including forcing him to resign from his position at Stanford. The lawsuit lasted six years and ended with a settlement that allowed him to keep some of the money and the cell samples.

During those six years, Congress passed the Bayh-Dole Act, which allows scientists to profit from government-funded research. The act, which would have undoubtedly made Dr. Hayflick’s earlier actions legal, helped catalyze the biotechnology industry.

Dr. Hayflick married Ruth Heckler in 1955. She died in 2016. In addition to his son, he is survived by four daughters, Deborah Curle, Susan Hayflick, Rachel Hastings and Annie Hayflick; eight grandchildren; and a sister, Elaine Rosamoff.

Dr. Hayflick later worked at the University of Florida and, from 1988, at the University of California, San Francisco, where he was professor emeritus.

His criticism of those who tried to find ways to extend human life was not just about practicality. He thought it was a terrible idea on principle.

“I’m an optimist,” he told The Guardian in 2001. “Anyone who believes in manipulating the human ageing process is a terrible pessimist. I don’t want to be alive when that becomes possible. I don’t want to give the next Adolf Hitler, Saddam Hussein, another 50 years of life.”

He continued: “Every time someone like that dies a natural death, people should thank their God, whoever he is, for the phenomenon of aging.”