When Edna Parker died on November 26, 2008, at the age of 115, the new oldest person in the world became Maria de Jesus of Portugal, also 115. Behind her is 114-year-old Gertrude Baines from Los Angeles, and there are 10 others behind her at 113.

There seems to be no shortage of successors to this most remarkable of honors. As of November 27, there were 89 “validated living” supercentenarians (i.e., those who are 110 and older): 79 women and 10 men, according to the Gerontology Research Group (GRG), a group of medical professionals that tracks the world’s oldest people. (The Validated Living Supercentenarians List is updated regularly.)  The GRG is quick to note, however, that the actual number of supercentenarians is much greater than 89—possibly between 300 and 450—but their ages can’t be confirmed.

Consider this feat by looking at the Centers for Disease Control and Prevention’s most recent data (2005) on longevity in the United States, the 2005 National Vital Statistics Report. Life expectancy (for both sexes and all races) is 77.8 years, with men living to 75.2 years and women to 80.4 years. Once you reach the age of 100, life expectancy extends a mere 2.6 years for women and 2.3 years for men. The CDC’s numbers don’t go any higher than that.

Documentation for this older age group is important because, as the New England Supercentenarian Study reports, “the majority of claims of age 115 and older are false.” Researchers start with a birth certificate and request other forms of proof that indicate ages at different times in a prospective supercentenarian’s life, such as census records, school report cards, military records, marriage licenses, employment records, old passports, and/or the age given on children’s birth certificates.

The New England study has enrolled more than 100 supercentenarians and is exploring the genetic and environmental factors that allow people to attain extreme old age. They hope to discover why some people are predisposed to longevity and less susceptible to the illnesses that can come with age.

The one thing these seniors seem to do especially well is postpone the debilitating chronic diseases of aging. In 2006, the New England study examined the characteristics of 32 supercentenarians and found that 41% of them required minimal assistance or were independent; few had a history of vascular-related diseases, including heart attack and stroke; only 22% were taking medication for hypertension; and 25% had a history of cancer but were cured. Only osteoporosis (44%) and cataracts (88%) were common ailments.

Other work is being done by the Supercentenarian Research Foundation (SRF), an international nonprofit organization that funds research into the biology of aging. The SRF hopes to determine why supercentenarians live longer than anyone else (and what limits their life span) and to identify the basic factors of aging that affect diseases of old age and shorten life expectancy of the general population.