Ultracentenarians: age goes up, but not the risk of dying
Is there a biological limit to human longevity? How is our risk of death correlated to ageing? To answer these questions, researchers from the Sapienza Department of Statistical Sciences, in collaboration with ISTAT – the Italian Statistics Institute and the Univesrities of Roma Tre, Berkeley and Southern Denmark, conducted a study on semi-supercentenarians (individuals aged 105 and over), with the aim of accurately estimating the risk of dying. The results of the research published on Science, have surprisingly shown the achievement of a constant level of the mortality risk at these extreme ages.
The team of researchers has estimated, for the first time, mortality at the highest ages with an accuracy and precision that had not been possible until now. "Our data, carefully documented - explains Professor Elisabetta Barbi from Sapienza - lead to the conclusion that the mortality curve grows exponentially up to about age 80, but then decelerates until reaching a plateau, that is a constant level, beyond age 105".
The study also showed that, even at these extreme ages, human mortality slowly declines across cohorts. "If there is a limit to longevity - comments Barbi - this has not yet been reached".
The lack of reliable data on these "pioneers of longevity" has fuelled until now a controversial debate among scientists all over the world. The scientific community is divided between those who maintain that the mortality curve continues to increase exponentially with age, and who instead argues that it decelerates and reaches a constant level (plateau) at the highest ages, mimicking the behaviour of other animal species.
The discovery of the plateau is crucial for understanding the mechanisms underlying senescence and human longevity. "For the scholars of the field - concludes Barbi - represents a first and important confirmation of the role played by the selective survival and provides the necessary empirical clarity for the progress of studies concerning evolutionary theories of senescence".
The Plateau of Human Mortality: Demography of Longevity Pioneers - Elisabetta Barbi, Francesco Lagona, Marco Marsili, James W. Vaupel, Kenneth W. Wachter – Science, 29 Jun 2018: Vol. 360, Issue 6396, pp. 1459-1461 DOI: 10.1126/science.aat3119
For further information
Elisabetta Barbi, Department of Statistical Sciences, Sapienza University