By studying the genomes of people over the age of 105, an international team of researchers has identified several genetic factors that appear linked to human longevity — and they center on the body’s ability to repair its own DNA.

The challenge: The world’s average life expectancy is 72 years today, but many people live decades longer.

Research suggests that genetics play a role in human longevity, but we don’t know precisely what it is that allows some people to live so much longer than others.