Despite humanity's best efforts to eradicate disease and improve well-being, there's a limit: Humans will probably never live much past 115 years of age, according to a new study published in Nature.
While experiments in animals have shown that genetics can be tweaked and drugs administered to increase lifespan, Jan Vijg and his team at the Albert Einstein College of Medicine argue that this doesn't mean we aren't subject to a hard maximum. In support of their hypothesis, they offer that once we get over 100, our survival rates haven't gotten any better; and that the age at death of the world’s oldest person has not increased since the 1990s. In what may be considered a pessimistic view, they figure that 115 might be the maximum age for humans, no matter how much money Silicon Valley billionaires, in the throes of their mid-life crises, throw at the problem.
Over the past century, life expectancy has risen rapidly. In France, for example, the average age at death has gone from around 50 to over 80 for females, with men a few years behind. The trend is the same everywhere in the developed world. Better medicine, better care, and healthier lifestyles all mean we're lasting longer than ever, and this increase in life expectancy is predicted to continue. But that's average lifespan, not maximum lifespan.
As a species, we are surviving longer, but that may just mean that more and more of us are pushing up against a hard limit. Imagine a world where nobody dies of disease, where we're all as fit as possible. What happens then? To find out, Vijg studied the ages at death of the world's longest-lived people. His team plotted the maximum reported ages at death (MRAD) in France, Japan, the U.K., and the U.S. These are the countries with the highest proliferation of supercentenarians, or folks 110 year old and more.
They found that the increase in death age plateaued around 1997, after spurt increase between the 1970s and the early 1990s. Before 1995, the MRAD increased by 0.15 years per year. After 1995 the increase stopped. In fact, the MRAD has decreased slightly since then. One problem with Vijg's results, though, is that there just aren't that many supercentenarians to count, so the sample size isn't big enough for accurate data. To combat this, the team moved down a few years to include people who had other high ages at death.
Vijg's conclusion is that human life-span is limited, probably to 115 years on average. As more and more of us live to supercentenarian-age, the data surrounding our maximum lifespan will get a lot better, or at least more plentiful, but the increase in supercentenarians in the past two decades means that Vijg's study should be more accurate than earlier attempts.
Is this depressing news? Maybe not. Consider that the world's longest-lived person so far, Jeanne Calment, who died in 1997 at age 122—someone the study says is a major outlier.
By that point, she'd spent over half of her life above retirement age. What if, instead of trying to increase the human lifespan, we instead focused on making our 115 years better. Or rather, we should try to make the good years we have even better. Being 70 no longer means you have to sit around all day outside the old-folks home, petting passing dogs, then eating soup for dinner. We should work on increasing the quality and number of our active years, perhaps with drugs to complement exercise and diet. Then, if we do get to 122 years old, we might still be in good enough shape to enjoy ourselves.
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