AMERICAN Edna Parker, the world’s oldest known person, celebrated her 115th birthday Sunday, defying mind-boggling odds.

    Her achievement was recognized by Guinness World Records last August after the death of a Japanese woman four months her senior.

    There are only 75 people alive — 64 women and 11 men — who are 110 or older, according to the Gerontology Research Group, a California-based organization that verifies reports of extreme ages.

    Parker, who was born April 20, 1893, has been a widow since her husband Earl died of a heart attack in 1938.

    She has also outlived her two sons — Clifford and Earl Jr. — but is far from lonely with five grandchildren, 13 great-grandchildren and 13 great-great-grandchildren to keep her company.

    “We don’t know why she’s lived so long,” said Don Parker, her 59-year-old grandson.

    “But she’s never been a worrier and she’s always been a thin person, so maybe that has something to do with it.”

    Scientists who study longevity hope that Edna Parker can help unlock the secrets to long life.

    Two years ago, researchers from the New England Centenarian Study at Boston University took a blood sample from Parker for the group’s DNA database of super centenarians.

    Her DNA is now preserved with samples of about 100 other people who reached the 110-year milestone, and whose genes are being analyzed, said Dr. Tom Perls, an aging specialist who directs the project.

    “They’re really our best bet for finding the elusive Holy Grail of our field — which are these longevity-enabling genes,” he said.

    On Friday, a birthday party for Parker was held at her nursing home in Shelbyville, Indiana.