News about what can lead to a long life comes out regularly. Sitting can cut years off your life. Taking multivitamins can lower cancer rates. Smoking is bad. Mediterranean diet good. Fatty foods bad. Stress bad. Exercise good. Some other advice: keep working; have lots of friends; drink a glass of wine a day. The list goes on.

But what happens really, when you crunch the numbers? According to two recent studies, you might be better off smoking than sitting and watching television for hours a day.

Scientists who surveyed 12,000 Australian adults, The Times reported, figured out that every hour of television that an adult watched after the age of 25 reduced his life expectancy by 21.8 minutes. The authors said smoking a single cigarette reduces life expectancy by about 11 minutes, The Times reported. An adult who spends an average of six hours a day watching TV in his life can expect to live 4.8 years fewer than a person who does not watch TV.

The results of another study of sitting were similar.

"Many of us in modern society have jobs which involve sitting at a computer all day," Dr. Emma Wilmot, a research fellow at the University of Leicester in England, who led a review of data from 18 studies involving 794,577 people, told The Times. "We might convince ourselves that we are not at risk of disease because we manage the recommended 30 minutes of exercise a day." But, she says, we "are still at risk if we sit all day."

Scientists studying DNA and other molecular biodynamics may soon offer a longer life to those who desire it. David Ewing Duncan wrote in The Times that over the past three years he has asked nearly 30,000 people at his lectures on trends in bioscience how long they want to live: 80 years, 120 years, 150 years (which would require a biotech breakthrough) or forever.

Some 60 percent chose a life span of 80 years. Another 30 percent chose 120 years, and almost 10 percent chose 150 years. Less than 1 percent desired immortality, he reported. After learning about the possibilities for extending life, including stem cell treatments, bionics or other drug regimens, few people wanted to live longer, Mr. Duncan wrote. Even when people were told that a pill had been invented to slow aging down by half, allowing a person who is, say, 60 years old to have the body of a 30-year-old, he said that only about 10 percent of people he talked to would favor a life span of 150 years.

Many were concerned about issues from extending the life spans of millions of people, including boredom, the cost of a longer life and the impact of so many extra people on earth. Some worried that millions of healthy centenarians would deprive younger people the jobs and opportunities that come about with the passing of generations.

Residents of the Greek island of Ikaria, where many live into their 90s, don't think too much about the passing of generations. Nor are they terribly concerned about time. Or money. They grow most of their own food, sleep as long as they like, have little interest in material goods and spend a lot of long afternoons and evenings socializing with friends over locally produced wine and homemade meals. These factors may contribute to Ikaria's striking rate of longevity, one of the highest in the world.

"People stay up late here. We wake up late and always take naps," Dr. Ilias Leriadis, one of the island's few physicians, told The Times. "Have you noticed no one wears a watch?" Dr. Leriadis pointed out what might be the islanders' secret to a long life: "We simply don't care about the clock here."

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