It’s a war out there. Even on the level of bacteria and other microbes, there’s a constant arms race, each side developing weapons to target the other’s weakness and defenses against the latest attacks. Humans are key players in this microbial one-upmanship, and so are other organisms. The tools of aggression produced by microbes are applied by higher forms of life and, in some cases, become useful products like human drugs. The vast majority of antibiotics now in use—penicillin, streptomycin, tetracycline, erythromycin, vancomycin, and many others—come from nature. Read more.