How Long Can People Live?
by Karen Hopkin
She took up fencing at age 85 and rode her bike until she was 100. She made her first movie appearance at age 114 and released a rap CD on her 121st birthday. When it comes to long life, Jeanne Calment is the world's recordholder. She was born before Edison invented the light bulb and lived to the ripe old age of 122. When asked the secret of her longevity, Calment guessed that God must have forgotten about her.
Calment died in 1997, and since then no one has broken her record. So is 122 the upper limit to the human life span? Or will people keep living longer and longer? If scientists come up with some sort of pill or diet that would slow aging, could we possibly make it to 150—or beyond?
Researchers who study the biology of aging have thought about these questions. And they don't entirely agree on the answers.
“When it comes to maximum longevity, everything is speculation,” says Jerry Shay at the University of Texas Southwestern Medical Center. “Jeanne Calment lived to 122, so it wouldn't surprise me if someone alive today reaches 130 or 135.”
Steve Austad at the University of Idaho agrees. “There's no evidence that there's a limit to human longevity,” he says. Experts used to say that humans couldn't live past 110. When people blew past that age, they raised the number to 120. Then Jeanne Calment thumbed her nose at that stop sign. So why can't we go higher?
The trouble with guessing how old people can live to be is that, in the end, it's all just guessing. “Anyone can make up a number,” says Rich Miller at the University of Michigan. And even a scientist's guess is still a guess. “Usually the scientist who picks the highest number gets his or her name in Time magazine.”
Technically, there's no “biological limit” to how long people can live, says Jay Olshansky at the University of Illinois. In other words, there's no special set of Death Genes that will switch on when it's time for us to check out. At the same time, animals that mature quickly and start reproducing early, like mice, tend to have shorter lives than animals that take their sweet time growing up, like turtles. Or humans. So people are already pretty long-lived. In fact, some researchers think that we might already be living as long as we can. Maybe the folks who live to be 100 or more are already doing something to give their longevity a little extra boost, says George Roth, who works at the National Institute on Aging. Without realizing it, these super-old folk could be taking in fewer calories, a treatment that has been shown to slow aging in mice and rats. In that case, says Roth, “120 might be close to the max.”
But what about all the new antiaging techniques that scientists are chasing? Won't they keep us alive for centuries? Actually, says Miller, any “miracle cure” for aging would probably keep most of us kicking until, oh, about 120. Look at it this way: Researchers right now are working on therapies that extend the life span of mice by 50 percent at most. So, if the average human life expectancy is about 80 years, says Miller, “adding another 50 percent would get you to 120.”
So what can we conclude from this little debate? That life span is flexible, but not infinitely flexible, says George Martin of the University of Washington. “We can get flies to live 50 percent longer,” he says. “But a fly's never gonna live 150 years.” Of course, if you became a new species, one that matures at a different rate, all bets would be off, he adds. Does Martin really believe that humans could evolve their way to longer life? “It's pretty cool to think about,” he says with a smile.
- longevity: The length or duration of life.
- therapies: The treatments for illnesses or disabilities.
- This article mentions the debate among scientists about whether or not science can help people live longer lives. Write a paragraph telling how you think the world would be different if most people lived to be 120 years old.
[anno: Answers will vary.]