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Long life expectancies called unlikely

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SAN FRANCISCO — Human life expectancy has increased by three decades since 1900 and may reach 85 for babies born in this century, but that may be near the upper limit unless science finds ways to dramatically slow the aging process, some researchers said Sunday.

Claims by some scientists that humans in this century will have a life expectancy of 100 or even 120 are not realistic and not supported by the trends measuring the rates of death, said S. Jay Olshansky of the University of Illinois, Chicago.

"We anticipate that many people here today will live long enough to witness a life expectancy of 85 years, but everybody alive today will be long dead before a life expectancy of 100 is achieved, if ever," said Olshansky.

The researcher was the head of a panel of experts that on Sunday analyzed trends in human life expectancy at the national meeting of the American Association for the Advancement of Science.

Olshansky said there are no "magic potions, hormones, antioxidants, forms of genetic engineering or biomedical technologies that exist today that would permit a life expectancy of 120 or 150 years as some people have claimed."

Leonard Hayflick, an expert on aging at the University of California, San Francisco, denounced what he called "outrageous claims" by some scientists that humans are capable to living well past 100 years.

Hayflick said even if the most common causes of death — cancer, heart disease and stroke — were eliminated, "the increase in life expectancy would be no more than 15 years."

With those death causes gone, he said, the true cause of death would be revealed: the aging process.

Aging, he said, is a decline on a molecular level that makes people "increasingly vulnerable to disease" and that this process is not receiving much research attention.

Instead, most aging research, said Hayflick, concentrates on the age-related diseases that can be easily identified, such as heart attack, stroke, cancer and Alzheimer's disease.

Nature designed humans to peak physically at about age 20, to assure reproduction and survival of the species, he said. After that, humans "coast for another four to five decades" and it is the length of this coast that determines longevity

Kaare Christensen of the University of Denmark said the future may not be as bleak as Olshansky and Hayflick suggest.

He said studies in Sweden, where every citizen has been listed on health roles for about 200 years, show that the upper limit for the oldest of the old at the age of death is still going up. A study published last year showed that the oldest person to die in that country in 1999 was 108.

Christensen said that the age at death of the oldest old continues to increase "and there is no evidence that we are pushing up against the limits."

But measuring the maximum age achieved by a remarkable individual does not directly correspond to life expectancy, which is a measure of how long half of the population born at a specific time can expect to live, said other experts.