Their debate about aging led to the half-billion-dollar wager, which is payable in 2150. Austad believes someone already born will provide the proof of the wager. Their bet reflects the estimated proceeds of a trust fund they created this year.

Austad bet that someone will live to be 150 years old by 2150. Olshansky bet that 130 years is the top end of the human lifespan.

The wager coincides with the release of a new book, "The Quest for Immortality: Science at the Frontiers of Aging" by Olshansky and his co-author, Bruce A. Carnes. Their book will be published Jan. 22 by W.W. Norton & Co.

Austad, a University of Idaho zoology professor at Moscow, Idaho, is the author of "Why We Age: What Science Is Discovering About the Body's Journey Through Life," originally published by John Wiley & Sons in 1997 and issued in paperback in 1999.

"Our body design, although beautiful to behold, miraculous in design and astonishing in its complexity, was never intended to be operated in the laboratory of extended life," Olshansky said.

Although Olshansky concedes it may be possible for individuals to reach the age of 130, he warns us to "beware what we wish for, because surviving to such extreme ages without significant changes to the rate at which we age, would produce a world filled with frailty and disability in older ages."

Biomedical technologies promise better than an even chance that at least one person will survive to be 150 years old by 2150, Austad believes. "We are closing in on the fundamental processes of aging, learning what drives them. Next we will begin to tinker," he wrote in the foreword to his 1997 book.

The progress continues, Austad said recently, bolstering his optimism. "We will live longer because cloning technology, combined with stem cell research, is likely to allow the growth of replacement parts (organs and tissues) in the not-too-distant future.

"I also think that we are now understanding the fundamental processes of aging, such as oxygen radical damage, well enough that pharmaceuticals and perhaps gene therapy to combat aging are likely within the next couple of decades -- in plenty of time to help someone alive today," Austad said.

"We really agree on just about everything," Olshansky said. "What we're really debating is what will be the world record for the human lifespan."

The wager reflects the scientists' agreement that simply being alive for 150 years does not count. To win, Austad's 150-year old must be cognizant and aware of his or her surroundings throughout life.

The result of their bet will be determined Jan. 1, 2150, by three scientists chosen by the president of the American Association for the Advancement of Science. The scientists will rely first on three standard forms of identification such as a birth certificate, marriage license, death certificate or other reliable and verifiable documents.

If such evidence proves elusive, Olshansky and Austad agree to defer to the scientific expertise and methods of the future to determine a person's age.

The heirs of the scientist who wins the bet will collect the prize. The $500 million total is the estimated value of a trust fund that the two men inaugurated this year with $150 apiece. The trust calls for each scientist and his heirs to contribute a minimal amount to the trust annually for the next 150 years.

If the winner has no living heirs in 2150, universities will emerge as the beneficiaries of their wager.

In Austad's case, the University of California at Los Angeles and University of Idaho would share the proceeds for undergraduate scholarships for biological sciences majors.

If Olshansky has no living heirs in 2150, he designated as his beneficiaries Michigan State University and University of Chicago, where he also serves as a senior research associate in the Center on Aging. - By Bill Loftus

[Contact: Steven N. Austad, S. Jay Olshansky, Bill Loftus, Jody Oesterreicher ]

12-Jan-2001