World's oldest known person to turn 115

Maybe it was a lifetime of chores on the family farm that accounts for Edna Parker's long life. Or maybe just good genes explain why the world's oldest known person will turn 115 on Sunday, defying staggering odds.

Scientists who study longevity hope Ms. Parker and others who live to 110 or beyond – they're called supercentenarians – can help solve the mystery of extreme longevity.

“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.”

On Friday, Edna Parker laughed and smiled as relatives and guests released 115 balloons into sunny skies outside her nursing home. Dressed in pearls, a blue and white polka dot dress and new white shoes, she clutched a red rose during the festivities.

Only 75 living people – 64 women and 11 men – are 110 or older, according to the Gerontology Research Group of Inglewood, Calif., which verifies reports of extreme ages.

Dr. Perls said the secret to a long life is now believed to be a mix of genetics and environmental factors such as health habits. He said his research on about 1,500 centenarians hints at another factor that may protect people from illnesses such as heart attacks and stroke – they appear not to dwell on stressful events.

“They seem to manage their stress better than the rest of us,” he said.