Researchers at the Max Planck Institute for Demographic Research in Germany used hunter-gatherer mortality data as a baseline to measure the rate of mortality reduction and how the probability of dying at specific ages has changed over time. They found that the bulk of mortality reduction has occurred since 1900 and that mortality at younger ages is now 200 times lower than that of previous generations. "The mortality revolution of the last 100 years is biologically unprecedented," Oskar Burger, one of the study's authors, said.
The researchers examined Japanese and Swedish men (two countries with the longest life expectancies). Their most striking finding: the mortality rates of hunter-gatherers are closer to those of wild chimpanzees (humans' closest living relatives) than they are to today's mortality profiles for Japan and Sweden.
The study, titled "Human Mortality Improvement in Evolutionary Context," notes that primitive hunter-gatherers at age 30 have the same probability of death as present-day Japanese person at age 72. "In other words, "compared with the evolutionary pattern, 72 is the new 30," the researchers write.
Indeed, humans have made great progress in extending our lives, and the sharpest reductions in death rates began to accelerate around 1900, according to the paper's authors.
The authors also compared the increase in human longevity to increases observed in fruit flies selectively bred to live longer. Their findings show that humans' ability for extended life is unprecedented, suggesting that the drop in mortality stems not from modifications to genes but from the environment – by making injuries and illness less fatal with advances in medical technologies and by improving health at older ages, as well other external sources like better "standards of living, education, public health, sanitation, medicine, housing and nutrition." They describe human mortality as being "plastic" and somewhat at odds with conventional theories of aging, which posit that harmful genetic mutations lead to accelerating death rates among individuals past childbearing age. But in fact, the lowest mortality is now experienced by people in their 70s and the chance of death of a 70-year-old Swede is less than one-tenth of the chance for hunter-gatherers.
Financial implications
Our extended life spans are already giving U.S. policy makers and the financial industry plenty of work trying to figure out how people can possibly make their savings last through a 30-year retirement. A 2011 survey by the Society of Actuaries, more than half of respondents underestimated population longevity. And even when individuals or couples do make a reasonably good estimate of remaining lifetime for people their age, far too few of them provide adequately for the consequences of out¬living average life expectancy, the report said.
Indeed, the implications are global. In its Global Financial Stability Report published last year, the IMF underscored the hefty implications to governments and economies of people living longer than expected, also known as longevity risk. Part of the issue is that governments have done their analysis of aging largely based on best guesses of population developments. But longevity has been consistently and substantially underestimated.
If average life spans by 2050 were to increase three years more than now expected, the already high cost of aging would increase by 50%, the IMF report said, and society would need extra resources equal to 1% to 2% of GDP per year.
