When antibiotics first came into use, they were so effective at curbing bacterial infections that it seemed the age-old battle of man vs. microbe would soon be at an end [1]. Eighty years and dozens of drugs later, we now know better. Following each new antibiotic’s launch, reports soon accumulated that once-treatable infections were becoming refractory to the drug [2]. Nowadays, many infectious strains are already resistant to multiple antibiotics [3]. Treating such cases is becoming more and more difficult, expensive and risky. Meanwhile, the supply of new antibiotics hasstalled.All thisaddsuptoamajorglobal crisis. It is already underway, and it is worsening every day [3]. The rise of resistance is simply adaptation—evolution in action. Bacteria’s large populations and their proclivity for swapping genes mean that mutants arise regularly, and thereafter, the fittest mutants spread through natural selection. So is resistance wholly inevitable? Not necessarily! Evolutionary theory not only explains why resistance occurs but it also offers clues as to how we might be able to prevent it—or at least slow it. Evolutionary perspectives