UCLA gerontologist Dr Stephen Coles said Mrs Parker's great-nephew notified him that Mrs Parker died Wednesday at a nursing home in Shelbyville, Indiana. She was 115 years, 220 days old, said Mr Robert Young, a senior consultant for gerontology for Guinness World Records.

Mrs Parker was born on April 20, 1893, in central Indiana and had been recognised by Guinness World Records as the world's oldest person since the 2007 death in Japan of Ms Yone Minagawa, who was four months her senior.

Dr Coles maintains a list of the world's oldest people and said Mrs Parker was the 14th oldest validated supercentenarian in history.

Ms Maria de Jesus of Portugal, who was born on Sept 10, 1893, is now the world's oldest living person, according to the Gerontology Research Group.

Mrs Parker had been a widow since her husband, Mr Earl Parker, died in 1939 of a heart attack. She lived alone in their farmhouse until age 100, when she moved into a son's home and later to the Shelbyville nursing home.

Although she never drank alcohol or tried tobacco and led an active life, Mrs Parker didn't offer tips for living a long life. Her only advice to those who gathered to celebrate when she became the oldest person was 'more education'.

Mrs Parker outlived her two sons, Clifford and Earl Jr. She also had five grandchildren, 13 great-grandchildren and 13 great-great-grandchildren.

'We don't know why she's lived so long,' Mr Don Parker said before his grandmother's 115th birthday. 'But she's never been a worrier and she's always been a thin person, so maybe that has something to do with it.'

Mrs Parker taught in a two-room school for several years after graduating from Franklin College in 1911. She wed her childhood sweetheart and neighbour in 1913.

But as was the tradition of that era, her teaching career ended with her marriage. Mrs Parker traded the schoolhouse for life as a farmer's wife, preparing meals for as many as a dozen men who worked on her husband's farm.

Mrs Parker noted with pride last year that she and her husband were one of the first owners of an automobile in their rural area.

Coincidentally, Mrs Parker lived in the same nursing home as Ms Sandy Allen, whom Guinness recognised as the world's tallest woman until her death in August. -- AP