Edited sentence: A November 2018 study advanced the hypothesis that Calment's daughter Yvonne usurped her identity in 1934, so that Jeanne actually died at age 59 and Yvonne, posing as Jeanne, was 99 years old upon her death in 1997.As Yvonne was born in 1898, this situation would have made the purported Jeanne 99 years old upon her death in 1997.In November 2018, Russian gerontologist Valery Novoselov and mathematician Nikolay Zak advanced the hypothesis that Calment's daughter Yvonne usurped her identity in 1934, by claiming that the daughter died instead of the mother, thus avoiding payment of estate tax.This would explain the statistically unlikely difference of several years between Calment's documented age and the next dozens of oldest persons ever recorded