Résumé
The exponential increase in the number of centenarians, which started just after World War II, is well documented in Europe and Japan. Much less is known about the population of extremely old persons reaching age 105-the semisupercentenarians-or age 110-the supercentenarians. The first cases of validated supercentenarians appeared in the 1960s, and their numbers have steadily increased since the mid-1980s. The current prevalence of known supercentenarians in low-mortality countries involved in the International Database on Longevity (IDL) is approximately 10 times higher than in the mid-1970s. In roughly 20 years, from 1980 to 2000, the maximum reported age at death, which was once assumed to indicate the maximum life span of the human species and seen as a stable characteristic of our species, has increased by about 10 years from 112 to 122 years. The annual probability of death at age 110 is about 50% and stays at that level through age 114. Our results strongly support the finding that mortality does not increase according to the Gompertz curve at the highest ages, and the results are consistent with a plateau between ages 110 and 115. The data after age 115 are so sparse that they are not analyzed here, but an earlier study suggested that mortality may fall after age 115. We intend to investigate this question in subsequent research.