Scientists at the University of Oregon have resurrected antimicrobial proteins dating back 160 million years, and laboratory tests show some of them kill drug-resistant bacteria better than their modern counterparts.

The research, published in the journal PLOS Biology on August 25, traced antimicrobial peptides through the evolutionary history of placental mammals. The team reconstructed molecules from the lactoferrin protein, which emerged alongside the earliest placental mammals near the end of the Jurassic period.

Peptides are short fragments of protein that form part of the body’s natural defences. In lab tests, some of the extinct versions proved more potent against drug-resistant bacteria than versions found in living species today.

The study was led by senior author Matt Barber, an evolutionary biologist at the university’s College of Arts and Sciences. He said the ancient molecules could become starting points for treatments that complement or replace antibiotics that no longer work.

Antibiotic resistance is one of the biggest global health challenges, making once-treatable infections harder to cure.