Since 1900, average life expectancy around the globe has more than doubled, thanks to better public health, sanitation and food supplies. But a new study of long-lived Italians indicates that we have yet to reach the upper bound of human longevity.

“If there’s a fixed biological limit, we are not close to it,” said Elisabetta Barbi, a demographer at the University of Rome. Dr. Barbi and her colleagues published their research Thursday in the journal Science.

Read more at The New York Times.