Tools

Of all the things you can learn from Harvard professor Nicholas Christakis, one of the most important is this: be terribly careful about the connections you make. I met him on a recent visit to Oxford, and as I shook his hand I called him Dr Nick. “It’s Nicholas,” he corrected. No one calls him Nick, not even his friends.

But friendship is a funny thing in Dr Christakis’s world, a place where personal encounters are sometimes no more important than connections with people you may never meet. After our handshake, he showed me pictures that looked like Spirograph doodlings in which the mooring pins had slipped and clusters of coloured nodes spread out seemingly randomly towards the paper edges.

But they weren’t random; they were all intertwined, and they turned out to be fundamental to his work. They showed inked patterns of obesity, happiness, sexual activity and smoking among groups of hundreds or thousands of people. Christakis became excited as he spoke about them.

“We’re not just social animals in the conventional way that people think,” he said, pointing to one of his clusters. “People affect each other even in things (like body size or emotional states) that many would not necessarily expect.” He talks in terms of “emotional stampedes” and “social chain reactions”. Christakis and his colleague James Fowler believe that some part of this is deeply embedded in our genetic heritage.

The pair’s recently published findings have created a global media hoopla and the work has been gathered in Connected, one of those popular social science books like The Tipping Point or Freakonomics that try to explain how we are influenced by the herding instinct of the crowd. Studying the behaviour of thousands of participants in the 62-year Framingham Heart Study in Massachusetts, they found that all sorts of things flow through social networks — violence, germs, misinformation, happiness and unhappiness, obesity and love — in ways that hadn’t previously been realised. Specifically, they suggest that we may be heavily influenced by people we don’t know, and their classic example concerns the ability of your friends’ friends to make you fat.

If someone on the study became clinically obese, their friends were 57 per cent more likely also to become obese. A friend of a friend of that obese person was about 20 per cent more likely to become fat, and this was the case even if the weight of the linking friend remained unaltered. A year later came their paper on smoking, which contained similarly arresting ties. If a person began to smoke for the first time, the chances of their friend doing so grew by 36 per cent.

The work of Christakis and Fowler is not all about getting cancer and plump; it is also about relationships and making money (and about how relationships can make you money). They explain how a friend has used social networks to analyse the success or otherwise of Broadway musicals. “He finds that if the key players — the director, costume designer, sound person, producer, etc — all worked together before, and everyone knows everyone else, then the show is a flop. He also finds that if you put together a group of people who have never worked together before, the show is also a flop. But if you put together a group of people some of whom have worked together and some who haven’t, then the show is a runaway critical success with enormous financial rewards.”

The authors also write favourably about the sprawling Medici family in medieval Florence, and of the business advantages to be gained from having the 15th-century equivalent of the large Rolodex (insider dealing at its best and most legal manifestation). Nothing new here, but the key is flexibility: the ideal combination consists of both strong and weak business ties, enabling the smooth severance of relationships when they are no longer viable.

But financial social networks can be more than just venal and selfish, the microcredit market showing the benefits to be gained from large groups of people helping those they don’t know. Charitable giving has, of course, also run on the same principles. “On balance, social networks do more good than harm,” Professor Christakis says. “In a deep and fundamental way, networks are connected to goodness.”

Connected: Amazing Power of Social Networks and How They Shape Our Lives, by Nicholas A Christakis and James H Fowler, £12.99, HarperCollins