Volunteers who were given a cocktail of drugs for a year actually aged backwards, losing an average of 2.5 years of their biological ages, according to the new study. The research showed that the marks on their genomes that represent their “epigenetic clock“, as well as their immune systems, actually improved despite the passing of time.

The scientists involved in the study were shocked by the results.

“I’d expected to see slowing down of the clock, but not a reversal,” researcher Steve Horvath from the University of California, Los Angeles told Nature, which first reported the findings. “That felt kind of futuristic.”