The rise of drug-resistant bacteria is one of the most important threats facing modern medicine. One by one, our arsenal of antibiotics is coming up short against microbes that can pump them out, slip under their notice, deactivate them, or even eat them. But these tricks aren’t new. Bacteria have been defeating antibiotics for millennia, long before Alexander Fleming noticed a piece of mould killing off bacteria in a Petri dish. And the best proof of that longstanding struggle has just emerged from the ice-fields of Alaska.

In 30,000-year-old samples of frozen soil, Vanessa D’Costa and Christine King from McMaster University have found a wide variety of antibiotic-resistant genes. They would have allowed ancient bacteria to shrug off many modern drugs such as tetracyclines, beta-lactams and vancomycin.

Vancomycin resistance is especially interesting. This drug has traditionally been used as weapon of last resort, a drug to use when all others have failed. When vancomycin-resistant bacteria first emerged in 1987, it was a surprising blow. Since then, resistant versions of more common bacteria, such as staph (VRSA) have reared their heads.

These superbugs neutralise vancomycin using a trio of genes ...