Across 160 million years of mammalian history, the immune system quietly refined a small protein — lactoferricin — into an increasingly precise weapon against bacterial infection. Researchers at the University of Oregon have now reconstructed that evolutionary journey in the laboratory, resurrecting ancient versions of the peptide to trace how single amino-acid changes produced dramatic leaps in antibacterial power. In an era when conventional antibiotics are losing ground to resistant bacteria, this deep reading of evolutionary memory offers not a ready cure, but something perhaps more valuab