ABSTRACT
Chemical warfare has been taking place since very early in the history of life on earth, and the design of chemical weapons by humans is an extremely recent event on the evolutionary scale. The synthesis by plants of secondary compounds (“toxins”), which are toxic to invertebrates and vertebrates that feed upon them, together with the development of detoxication mechanisms by the animals in response, has been termed a “coevolutionary arms race” (Ehrlich and Raven 1964, Harborne 1993). Animals, too, have developed chemical weapons, both for attack and defense. Spiders, scorpions, wasps, and snakes possess venoms that paralyze their prey; bombardier beetles and certain slow-moving herbivorous tropical sh produce chemicals that are toxic to other organisms that prey upon them (see Agosta 1996). Microorganisms produce compounds that are toxic to other microorganisms that compete with them (e.g., penicillin produced by the mold Penicillium notatum). Thus, chemical weapons of both attack and defense are widely distributed in nature, and are found in many different species of animals, plants, and microorganisms.
