Amy Middleton
Amy Middleton is a Melbourne-based journalist.
Humans may have already hit the ceiling when it comes to the oldest human age possible.
Using age-of-death data, a US study published in Nature predicts the likelihood of a single human living beyond the current world record of 122 years – and the outlook isn’t great.
Jan Vijg at the Albert Einstein College of Medicine in New York and colleagues wanted to weigh up whether the oldest possible age for a human is fixed at a certain number, or if it’s flexible, more like our life expectancy.
The average expectancy for human life has risen dramatically across most countries over the past century, but this is largely because we’ve managed to survive birth and early childhood.
Studies also show a dramatic increase in the oldest recorded age across the world, but that momentum has plateaued since the 1990s. The oldest person on record is still Jeanne Calment from Arles, France, who passed away in 1997 at 122 years old.
Does this mean we’ve reached the maximum age for a human being?
To model this, the researchers gathered data from the Human Mortality Database and the International Database on Longevity, each of which records mortality across 41 countries and territories.
The team homed in on France, Japan, UK and US – countries with the most recorded supercentenarians (people over 110 years old) between 1968 and 2006.
Their results suggest that before 1995, maximum age of death increased by 0.15 years every year, but after 1995 that growth slowed and even began to lessen.
These rates were verified against data recorded by an independent research group.
Vijg and colleagues then used their scale to model our maximum age of death into the future. They found that the probability of anyone living over 125 was as low as one in 10,000.
“Our results strongly suggest that the maximum lifespan of humans is fixed and subject to natural constraints,” the paper reads.
The team also examined the increase over time in our survival at specific ages. For instance, the likelihood that a human will survive past 70 has increased dramatically in France and other countries since the 1900s.
The idea of a “natural limit” to life doesn’t imply that it’s direct byproduct of a genetically driven program that causes ageing and death, writes S. Jay Olshansky, from the University of Illinois at Chicago in the US, in an accompanying News and Views article.
“It means that there is no fixed limit beyond which humans cannot live, but that there are nevertheless limits on the duration of life that are imposed by other genetically fixed life-history traits.”
Although interventions into these genetic programs are being investigated, the researchers say this is a massive task given the huge range of genetic variants that determine our lifespan.
