Let me tell you the story of the most successful organism of all time: this is the story of the parasite. ... Early on, evolution branched into two distinct paths: independent organisms-those that exist on their own in the natural world-and parasites-organisms that live on other organisms. And it was, by far, the parasites that proved the more successful of the two branches. Today, for every independent organism in nature, there exist three parasites. ... These two strains of evolution have been locked in a primordial arms race, constantly evolving to best each other for supremacy of this planet. As parasites evolve to perfect their systems against a species of host, the host evolves to evade their attack. Scientists call this theory of an eternal genetic struggle the Red Queen Hypothesis-a name taken from Lewis Carroll's Through the Looking Glass.