A kabob-shop owner in Frankfurt finds—through a network of acquaintances—that the social distance between himself and Marlon Brando really is only the fabled six degrees of separation. Meanwhile, a mathematician randomly distributes 150 letters in Kansas with the instructions that they be sent to a broker in Boston, without revealing the broker's address; remarkably, the letters that make it arrive in six steps or less. Thus, author Buchanan, a science writer and former Nature
editor, introduces readers to the dynamics of networks and shows how these networks affect behaviors in both the natural and the social world. Armed with conceptual mathematics, Buchanan goes in search of all kinds of "small-world" networks and finds the same patterns taking shape in food chains, in the neuronal networks of insects, in the architecture of the Internet and in the cultural backgrounds of elite CEOs. The world, in short, is moved by shifts and adjustments in these tiny worlds. Capitalizing on this knowledge, he argues, might reveal, e.g., why the rich get richer, why the Internet functions smoothly and how small-world networks can combat the spread of AIDS. Buchanan's ability as an affable, easygoing storyteller makes up for myriad digressions, and the narrative is, at times, spellbinding. Unfortunately, it takes scores of pages before the author addresses how his concepts might be used in the real world. Readers may still be left wondering just what the practical implications are of these complex and elegant mathematical models. (May)
