Human longevity has improved so rapidly over the past century that 72 is the new 30, scientists say.
Researchers at the Max Planck Institute for Demographic Research in Rostock, Germany, said progress in lowering the odds of death at all ages has been so rapid since 1900 that life expectancy has risen faster than it did in the previous 200 millennia since modern man began to evolve from hominid species.
The pace of increase in life expectancy has left industrialized economies unprepared for the cost of providing retirement income to so many for so long.
The study, published in the Proceedings of the National Academy of Sciences of the United States, looked at Swedish and Japanese men – two countries with the longest life expectancy today. It concluded that their counterparts in 1800 would have had lifespans that were closer to those of the earliest hunter-gatherer humans than they would to adult men in both countries today.
Those primitive hunter gatherers, at age 30, had the same odds of dying as a modern Swedish or Japanese man would face at 72.
Scientists who worked on the study said it was unclear what the possible upper limit for life expectancy would be. "How much longer can we extend life?" said Oskar Burger, lead researcher on the study. "We just don't know."
The study did not try to draw conclusions about whether the extension of human life was moral or desirable, or whether it could occur without depleting the faculties needed to enjoy the extra years.
Instead, it tried to look at how the odds of dying at specific ages had changed over time. The researchers used longevity data from chimpanzees in captivity to estimate lifespans for pre-humans and data from modern day hunter-gatherer tribes as a benchmark for early human lifespans.
"The recent jumps in mortality reduction are remarkable in the context of mammal diversity because age-specific death rates for hunter-gatherers are already exceptionally low, probably among the lowest of any non-human primate," the study noted.
In fact, the rate at which human life expectancy is rising is even faster than that achieved by scientists when they tried to breed organisms such as fruit flies to create genetically engineered long-living species. Although these experiments produced sharp rises in longevity, the rise in human longevity over the past century, which is not based on genetic improvements, has been much starker.
Mr Burger noted that the very rapid improvement in lifespans coincided with the invention of antibiotics and vaccines, huge improvements in agricultural efficiency that made food far more available and the widespread development of systems that made clean water more readily accessible.
Human mortality, he added, has shown itself to be far more "plastic" and capable of manipulation than anyone had imagined.