We spend a good amount of time on this blog discussing the new uses of the biocidal properties of copper. We look to the past civilizations that used copper to kill bacteria without knowing the mechanisms behind it - the Ancient Egyptians who used copper in wounds, the Ancient Greeks who used it in plumbing, and the seafaring explorers who used it to store drinking water. But there is actually a far, far more ancient use of copper to combat infection: Our own innate immune system.