The risk of death decreased if you get really, really old. A new study suggests that once you’ve managed to get really old, you’ll probably become even older.
The risk of dying, your ‘mortality’ as it is called in the research community, increases exponentially as you grow older. But maybe not indefinitely. This ‘universal truth’ may not hold after the age of 105 since it seems that the risk of death plateaus above that age.
This apparent plateau indicates that we have not reached the limit of how old we can become; hence, there is no clear biological limit to our age.
The study has been published in the journal Science and is based on data from almost 4,000 really old Italians, every one of them over 105 years. The researchers then aimed to assess the quantitative risk of death at different ages.
The research data showed that people at age 110 had the same continued chances of survival as those between the ages of 105 and 109—a 50/50 chance of dying within the year and an expected further lifespan of 1.5 years.
“Our data tell us that there is no fixed limit to the human lifespan yet in sight,”
“Very few of us are going to reach those kinds of ages, but the fact that mortality rates are not getting worse forever and ever tells us there may well be more progress to be made improving survival past the ages of 80 to 90. This is a valuable, encouraging discovery.”
– Senior author Kenneth Wachter, a professor of demography and statistics at the University of California, Berkeley.
The researchers were able to draw an upper maximum of the curve of mortality, which steadily inclines the older you get, but then slows down and plateaus. The risk is then constant, and even if you become older, the odds to die seems to be unchanged.
Obviously, getting this age is about having the right genes and the right living habits. There is also a bit of natural selection when studying very old people, which evolutionary demographers like Wachter and study co-author James Vaupel point out. They theorize that those who survive do so because of demographic selection and/or natural selection. Frail people simply tend to die earlier, while robust people, or those who are genetically blessed, can live to extreme ages.
Reference:
E. Barbi et al., 2018. The plateau of human mortality: Demography of longevity pioneers. Science. Doi: 10.1126 / science.aat3119