isset（Is there a set limit to how long humans can live）

New research has revived one of the longest standing, and biologically fundamental, debates in the life sciences: Is there a set limit to how long humans can live?

The study, published in the journal Science, suggests that maybe there isn’t. (It should be noted that this finding contradicts other, similar research by biologists and demographers, as Nature notes.)

Researchers examined a population of nearly 4,000 Italians who were 105 years or older. What they found was that mortality risk essentially plateaus after a certain point for these “super-elderly” individuals. The risk of death increases gradually the older that someone gets, especially as they reach their 80s and 90s. But, say Sapienza University’s Elisabetta Barbi and University of Roma Tre’s Francesco Lagona, after reaching the ripe old age of 105, the odds of dying within the following year essentially drop down to 50%.

The researchers emphasized the quality of their dataset, asserting that their “estimates are free from artifacts of aggregation that limited earlier studies and provide the best evidence to date for the existence of extreme-age mortality plateaus in humans.” If a mortality plateau really does occur at higher ages, that theoretically means death doesn’t have to be an inevitability.

Not all scientists have reached that conclusion. For instance, a team from New York’s Albert Einstein College of Medicine analyzed the ages of the world’s oldest people and pegged the maximum length of human longevity at somewhere between 115 and 125 years. (For the curious: The oldest person ever in recorded history was a French lady named Jeanne Calment, who died at 122 years of age in 1997.)

“By analyzing global demographic data, we show that improvements in survival with age tend to decline after age 100, and that the age at death of the world’s oldest person has not increased since the 1990s. Our results strongly suggest that the maximum lifespan of humans is fixed and subject to natural constraints,” wrote the Albert Einstein researchers in their 2016 report.