A newly released study has floated the idea that there are inherent limits to the human aging process and longevity. The findings, based on demographic analysis and trends, suggests that humans have already begun to bump against the ceiling of the maximum possible lifespan and that few will end up growing past age 125.
The analysis uses data on life expectancy from 41 different countries and looks back over the past century. It was observed that the human lifespan has risen significantly over this period and that the improvements were due to a number of different factors. These factors included, but are not limited to:
- Advances in childbirth and maternity care (i.e.: lower child mortality)
- Improvements in access to clean water
- Development of vaccines and antibiotics
They also noted that, although the proportion of people who survive to age 70 has gone up since 1900, the rates of improvement afterwards seem to see diminishing returns. For instance, those between ages 70 and 100 have seen improved levels of survival. For those who are aged 100 or more, however, life expectancy has not changed that much. Simply put, medicine is not very good at reducing the mortality rate of people over 100 years old.
When the examination focused on data from France, the UK, the US, and Japan, a sort of plateau was noted. These countries were chosen because they have the highest proportion of “supercentenarians,” people aged 110 or older. Although the maximum age at death rose by about 0.15 years annually between 1970 and the early 1990s, by the mid-to-late ‘90s, the maximum age leveled off at 115 and has not changed since.
The researchers began to run some modeling and future predictions and determined that, based on the data, the odds of a person living beyond age 125 is about 1 in 10,000. Incidentally, the oldest known human, Jeanne Louise Calment, was 122 when she died in 1997.
The reason for this “wall of mortality” appears to be a combination of inherent limits to the aging process and various genetic programs. Medicine is able to address specific problems such as a heart condition or a lung disease, but it is not capable of effectively handling the overall, systemic decline that is experienced in old age. Eventually, flaws
and damage simply build up to the point where there isn’t a way to respond effectively.
The one major caveat to all of this, however, is that it is based on knowledge of things as they stand now. Plenty of research is ongoing as people try and learn more about the aging process and how to tinker with longevity. Although the study indicates that the human lifespan hasn’t gone up recently, it doesn’t mean that an increase isn’t possible—just that it won’t be without further work and understanding.
Dong, X., et. al., “Evidence for a limit to human lifespan,” Nature, 2016; 10.1038/nature19793.