Want to live the longest life you possibly can? The secret seems to be to just hang in there.

A study of the very oldest people alive in Italy shows that once they reached the age of 105, they were less likely to die right away than younger people.

It might seem counterintuitive, but there’s something about people who make it to super-ager status that keeps them alive. An international team of researchers thinks it might be evolution. People may be evolving to live longer, they report in the journal Science.

“The increasing number of exceptionally long-lived people and the fact that their mortality beyond 105 is seen to be declining … strongly suggest that longevity is continuing to increase over time and that a limit, if any, has not been reached,” the team, led by Elisabetta Barbi of Sapienza University of Rome, wrote.

Many groups have studied people who live to extreme old age and it is clear that genes are very important, with lifestyle coming in second.

But it’s difficult to study the very aged. For one thing, until recently it has been difficult to verify the birth dates of people more than 100 years old.

“Even in countries with reliable vital registration, age exaggeration is common among the oldest old,” they wrote.

Barbi’s team used verified data from Italy. “The project includes all individuals 105 and older in the period from 1 January 2009 to 31 December 2015,” they wrote. They collected birth certificates of the oldest, just to be sure.

They ended up with details on 3,836 Italians who lived to be older than 105.

Then they plotted mortality, to see when people died and if there was a pattern. There was. Once people reached 105, the rate of death fell. Of course, they will all eventually die, but the rates were lower as they got older.

“When a mortality curve levels out, it is said to reach a plateau,” Barbi’s team noted. And the death rate plateaus after age 105, they found.

“By using clean data from a single nation and straightforward estimation methods, we have shown that death rates, which increase exponentially up to about age 80, do decelerate thereafter and reach or closely approach a plateau after age 105,” they wrote.

Other studies have found that super-centenarians are exceptionally healthy, given their age, and that they often do not live their last years being sick and frail.

The longest validated lifespan is for Frenchwoman Jeanne Calment, who died in 1997 at when she was 122 years and 167 days old.

The Gerontology Research Group, a U.S. network that tracks the super-old, says 36 are currently living. Chiyo Miyako of Japan, who is more than 117 years old, is currently the oldest verified living person, followed by Giuseppina Projetto-Frau of Italy, who is 116.

The last surviving person born in the 1800s was Italian Emma Morano, who died in 2017 at the age of 117. She was born in November of 1899 and so her life spanned three different centuries.

The trend is moving the wrong way for the United States, however, where life expectancy is falling.