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No. 499:
How Old Will You Be?

Today, we lay up store against winter. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

You hear a lot of claims about long lives. But no one has ever verified a lifetime of more than 120 years. When we talk about extending human life, we really mean seeing how close we can get to that apparent natural limit.

Life expectancy involves three issues: One is disease. Eliminate cancer, and life expectancy will rise. Another is natural deterioration, even in healthy old age. Finally, we ask if we can ever silence the ticking of our genetic clock. Can we find a Fountain-of-Youth cure for the aging process itself?

I'll leave Fountains of Youth to science fiction. They're not on the horizon yet. We have to make peace with the competing forces of disease and aging. The more disease we eliminate, the more we have to worry about the quality of late life.

For example, women's life expectancy went from 46 years in 1900 to 84 in 1988. We've reduced both infant mortality and disease. Now our diet is improving. We smoke and drink less. The result: we'll see far more old people in the 21st century.

So we have to ask about the quality of our grandchildren's extended lives. Some factors that extend life also extend its quality. My father lived to be 86, but smoking-related ailments made his last 25 years very unpleasant. He would've lived a little longer as a non-smoker. More important, his last years would've been so much happier. So it's time to worry less about fatal diseases than ones which disable us in late life.

Life expectancy will get to 100 years, even without inventing a Fountain of Youth. So you and I had better think more clearly about how to use the gift of old age.

And it can be a gift. When I was a student, I swam to blow off physical energy. Every day I saw the same 70-year-old chemistry professor. His name was Joel Hildebrand. He also had to blow off energy.

I watched him swim his laps and wondered what it meant to look back on his long and distinguished life. I didn't know it then, but he wasn't looking back at all. He had almost as much career ahead as he did behind. Hildebrand published his last paper just after his 101st birthday.

The mind, of course, is our most reliable source of pleasure. It's also the last organ to go, as long as the body doesn't betray it. Creative minds are what will serve the quality of longer life in the 21st century. That's a gift we've too often squandered in the past. It's one we'd better learn to hang on to, as more of us start observing 80th and 90th birthdays.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Olshansky, S.J., Carnes, B.A., and Cassel, C., In Search of Methuselah: Estimating the Upper Limits to Human Longevity. Science, Vol. 250, November 2, 1990, pp. 634-640.