According to the scientists behind an study in Nature, modern-day humans have reached their maximum age limit.
Like most statements, this one has supporters and skeptics. The authors of the Nature study said that continued advancements in medicine will not and have not increased today’s age limit since the 1990s. However, studies manipulating the genetics of small animals and insects led other scientists to believe the maximum human age limit can still increase with similar manipulations and medications.
According to the Human Mortality Database—a database containing the population and mortality data for 38 countries across the world, the increase of human life expectancy in the past was due to reduced infant mortality, but now life expectancy is increasing because more people are surviving old age which the study classified as living past 70.
The scientists plotted the ages at death from the HMD across 1910 to 2010 to display how lifespans increased until the 1980s. The data from the 11 countries in the HMD at the time followed a similar pattern 88 percent of the time. The authors said this result suggests that humans do have a set lifespan.
With lifespan seemly accounted for, the scientists studied the absolute age limits of our species.
The scientists pulled maximum reported age at death data from the world’s top four countries,the United States, the United Kingdom, France and Japan, with supercentenarian citizens—people over the age of 110—and charted the data from the 1970s till 2015. They discovered that before 1995 supercentenarians continued to age 0.15 years per year, but after 1995, people began dying 0.28 years earlier per year. The age of supercentenarians plateaued at 114.9 after the 1990s.
The authors of the study accepted 115 years of age as the maximum human age with the possibility that some people will live to be older.
“…the probability of an MRAD [maximum reported age at death data] exceeding 125 in any given year is less than 1 in 10,000,” according to the Nature study.
The study concluded that human life does have an absolute limit, but their small sample size does leave room for error.
The director of the Max Planck Institute for Demographic Research, James Vaupel, said Japan among other countries expects children born in 2015 to live for 83.7 years, according to an additional Nature article.
This paper has “one-sided conclusions,” said Vaupel.
Advances in lifespan extension in test animals led some scientists to believe there is hope that more people will live past their 100th birthday.
“In worms, mice and flies, for instance, researchers have radically extended lifespan by suppressing genes involved in growth-factor signalling, or by restricting food,” according to the Nature article. “Human cells have been rejuvenated by delivering RNA encoding a protein that extends telomeres, protective caps on the ends of chromosomes that are associated with ageing and disease.”
Such studies cannot be compared to human longevity, because the animals tested were bred for extended life, said the lead scientist, Jan Vijg.
Future studies hope to focus on the biological systems encoded in our DNA that affect how long humans can live; however, the answer to genetically manipulating humanity’s way to a long life could be hidden within countless genes.
“I’m not saying drugs or tissue engineering couldn’t be very beneficial to increase our average lifespan, but will they really enable us to break through this ceiling of 115? I find that highly unlikely,” Vijg says in Nature. “Lifespan is controlled by too many genes. You could maybe plug one of those holes, but there are still another 10,000 other holes springing up.”