Watts didn't start off in sociology. Growing up in a small town in southeast Queensland, Australia, he thought he wanted to be a physicist. Then, more or less out of the blue, he decided to join the Navy, attending college at Australia's national military academy. After graduation, he owed five years of service. "I really wanted to go to sea, but I had bad eyesight and they wouldn't let me," Watts recalls with a rueful laugh, "so I ended up in all these jobs I didn't like." Watts wound up in his nation's version of the Pentagon, doing work that eventually sparked an interest in sociology and—though he didn't have a name for it then—network science. "One thing you learn in the Navy is that you never want to use the chain of command, even though you're always supposed to, because it breaks; everything goes up and gets jammed," he says. "So instead you go horizontally. You find the person over in Supply Squadron who was a classmate of a friend of yours, and get them to help you get whatever you need. Whereas, if you go through your commander's commander's commander, nothing will ever happen."
The lesson, he says, is that there's an important distinction between how we think the world works and how it actually functions. While we're comfortable with the idea that a few trendsetters dictate fashion, for example—or that a Patient Zero is responsible for the spread of a deadly disease—the truth is far messier and more complicated. "We bring to bear common sense that seems right to us," he says. "It seems right that the world is hierarchical. If we try to understand how information flows, we say there's got to be someone special doing it, otherwise we don't know how to understand it. We don't have a way of thinking of decentralized systems. When people tried to understand how the brain works, they thought there must be a little guy in there making all the decisions."
'I've spent my whole life doing what other people aren't doing. I pretty much always gravitate to the crack between the stools.'After a couple of years in the Navy, Watts applied to graduate school, winning a Fulbright to study theoretical and applied mechanics at Cornell. (He was eventually able to avoid returning to military service by reimbursing the government for his training costs.) On the Hill, he worked under Strogatz on a project that started with how networks of tree crickets synchronize their chirps, and wound up as a career maker. In work that essentially served as a roadmap for modern network science, Watts and Strogatz cracked what's known as the "small world" or "six degrees" problem—why, even in a system as large as the population of the Earth, a relative handful of connections unites us all. In the paper—"Collective Dynamics of 'Small-World' Networks," published in Nature in June 1998—the researchers demonstrated the "six degrees" phenomenon in three disparate systems: the power grid of the western U.S., the neural network of the worm C. elegans, and collaborations among actors on the Internet Movie Database.
The paper caused a sensation, prompting stories in the national media—a popular parlor game at the time was "Six Degrees of Kevin Bacon"—and helping Watts get his first book, Small Worlds: The Dynamics of Networks Between Order and Randomness, published by Princeton University Press. It remains one of the most cited papers in the field, with more than 20,000 citations on Google Scholar. But Watts notes that it almost didn't get published, initially being rejected by Nature because the reviewers didn't know what to make of it; one of them dismissed it in two highly critical sentences. "There was no such thing as network science," Watts notes. "I didn't even know what to call what I was doing. It wasn't sociology. It wasn't graph theory. There were no jobs and no funding. Before Steve would let me work on the problem, he made me promise that I wasn't interested in having an academic career."
But he did have one; he went on to become a full professor in sociology at Columbia, eventually leaving because, as he puts it, “all my time was sucked up by everything except research.” Jettisoning a tenured professorship at an Ivy League school may sound like career suicide—but it’s typical Watts. “I’ve spent my whole life doing what other people aren’t doing,” he says. “I pretty much always gravitate to the crack between the stools.” He spent five years at Yahoo Research before moving to Microsoft about a year ago. “I’m still interested in the same problems as when I was working with Steve,” Watts muses. “Collective dynamics of social networks—whether it’s risk in financial systems, epidemics of disease, outbreaks of political violence, or changing social norms. These are the biggest issues of our time and they affect everyone, but we have very little idea of why they happen. It’s endlessly shocking to me how unscientific we are about how we go about solving these big social and economic problems—that we leave it to our instincts to make these weighty and consequential decisions. So that’s the mission; that’s what gets me excited.”
Watts is well aware of the fact that he is, in many ways, a poster child for cumulative advantage—how flukes can engender long-term success. He went to grad school because the Navy wouldn't let him go to sea. The Nature paper got a second look because that one review was so peremptory, the editor sent it out again. The paper gave him the cachet to get Small Worlds published; that book's editor was instrumental in getting his next one, Six Degrees: The Science of a Connected Age, published by another house. Six Degrees helped him get tenure at Columbia—and so on. "People often think it's depressing to say that things are random, they're unpredictable, and that undercuts their meaning," Watts muses. "They think if the Mona Lisa is just an accident, they'll never be able to look at it the same way again. But meaning is different from explanation. It's true that if we re-ran history, some other painting would be famous and not the Mona Lisa. It's probably true for your life, your relationships; how I met my girlfriend was a total accident that could easily not have happened. Almost anything of importance—meeting Strogatz—was a random fluke. But meaning is a different thing. To say that something is random is not to say that it's not meaningful. Meaning is a construct that we place on the event once we know it's important."