Everything Is Obvious_ _Once You Know the Answer - Duncan J. Watts [40]
The headhunter would speak to the headman of his village, who would speak to the trader who came to buy copra, who would speak to the Australian patrol officer when he came through, who would tell the man who was next slated to go to Melbourne on leave, etc. Down at the other end, the cobbler would hear from his priest, who got it from the mayor, who got it from the state senator, who got it from the governor, etc. We soon had these close-to-home messengers down to a routine for almost everybody we could conjure up, but we would get tangled up in long chains at the middle until we began employing Mrs. Roosevelt. Mrs. Roosevelt made it suddenly possible to skip whole chains of intermediate connections. She knew the most unlikely people. The world shrank remarkably.4
Jacobs’s solution, in other words, assumes that social networks are organized in a hierarchy: Messages flow up the hierarchy from the periphery and then back down again, with high-status figures like Mrs. Roosevelt occupying the critical center. We are so used to a world of hierarchies—whether inside formal organizations, across the economy, or in society—that it is natural to assume that social networks should be hierarchical as well. Karinthy, in fact, used a similar line of reasoning to Jacobs’s, where in place of Mrs. Roosevelt he invoked Mr. Ford, writing that “to find a chain of contacts linking myself with an anonymous riveter at the Ford Motor Company … The worker knows his foreman, who knows Mr. Ford himself, who in turn is on good terms with the director general of the Hearst publishing empire. It would take but one word from my friend to send a cable to the general director of Hearst asking him to contact Ford who could in turn contact the foreman, who could then contact the riveter, who could then assemble a new automobile for me, should I need one.”
As plausible as this method sounds, however, it is not how messages actually propagate through social networks, as we know now from a series of “small-world experiments” that began not long after Jacobs was writing. The first of these experiments was conducted by none other than Stanley Milgram, the social psychologist whose subway experiment I discussed in Chapter 1. Milgram recruited three hundred people, two hundred from Omaha, Nebraska, and the other hundred from around Boston, to play a version of the messages game with a Boston stockbroker who was a friend of Milgram’s and who had volunteered to serve as the “target” of the exercise. Much as in Jacobs’s imaginary version, participants in Milgram’s experiment knew whom they were trying to reach, but could only send the message to someone whom they knew on a first-name basis; thus each of the three hundred “starters” would send it to a friend, who would send it to a friend, and so on, until someone either refused to participate or else the message chain reached the target. As luck would have it, sixty-four of the initial chains made it all the way to their destination, and the average length of those that did was indeed about six; hence the famous phrase “six degrees of separation.”5
But although Milgram’s subjects were able to find paths as short as those hypothesized by Karinthy and Jacobs, it wasn’t because they employed Mrs. Roosevelt or anyone like her. Instead, ordinary people passed messages to other ordinary people, tracking along the same social stratum rather than going up and down the hierarchy as both Karinthy and Jacobs imagined. Nor did the chains get tangled up in the middle as Jacobs worried they might. Instead they experienced their greatest difficulties after they had already gotten close to their targets. Social networking, it seems, is less like a pyramid than it is like a game of golf—where, the old adage goes, you “drive for show, putt for dough.” When you are far away from the target, that is, it’s relatively easy to jump large distances simply by sending the message to someone in the right country, and from there to someone in the right city, and then to someone in the right profession. But once you