L. Stephen Coles, 73, who spent his career studying the reasons that supercentenarians - or those who live to 110 or more - survived as long as they did, died Wednesday in Scottsdale, Ariz., of complications from pancreatic cancer, two colleagues said.

Mr. Coles wanted to learn how to slow "and ultimately reverse" human aging within 20 years, according to the website for the Gerontology Research Group, which he founded.

He lived in Los Angeles but was in Arizona toward the end of his life so he could be put in cryopreservation when he died, said Robert Young, who worked with Mr. Coles for 15 years.

Mr. Coles, who was also a university professor, was described by colleagues as a pioneer in the field of gerontology. He spent decades tracking the world's oldest human beings, studying their genomes and DNA sequences in hopes of finding out why some people outlived others by so many years.

Mr. Coles' more than 100 scientific journal articles made him a leader in his field, Young said, and revolutionized the study of aging. - AP