Christakis and Fowler have written a book (actually, a while ago, it was published in 2010) compiling available research on the power of social networks. I started reading this book a few weeks ago and have become completely evangelical about it ever since. It’s tone is excitable, and the enthusiasm is contagious. A few times I had to stop reading to remind myself I already knew much of what they were describing (it recalls old concepts of social capital and community resources), and yet they describe it so it sounds sparkly and new. Who doesn’t love their friends? This book is about the power of your friends, your friends’ friends, and then their friends.
I am not the only one reading this. The philosophy of the book rang through Melinda Gates’s recent commencement speech at Duke: “human connection is not a means to an end. It is the end – the purpose and result of a meaningful life – and it will inspire the most amazing acts of love generosity and humanity”.
This book was the positive inverse of work I did for the WHO on social exclusion – where I basically identified that the many “pro-social” health interventions that capitalize on social networks also, at once, increase the sting of social isolation. This work was a bit of a downer.
Christakis and Fowler’s work in this area started through an analysis of the meticulous records of the Framingham Heart Study, conducted from 1948 to the present in a small Massachusetts community. They mapped out the relationships of 12,067 people with more than 50,000 ties (connections between friends and relatives) among them.
They found that obese people tend to be friends with other obese people, while thin people tend to be friends with other thin people. Not so surprising, my social world often seems small too. However, the authors went a step further and concluded that the relationship was causal: being associated with overweight people, even indirectly, is likely to make you overweight.
The network map of the Framingham study, showing how obesity is socially contagious
The field of health behavior has understood the power of social networks for some time, and their existence and influence is often capitalized upon by recruiting socially influential peer educators to spread positive health behaviours through networks. The microcredit group lending model also capitalizes upon social networks to secure loans without collateral to women in villages (see my article on this here).
However, the exact nature of how networks work was news to me, and the fact of how they seem to operate independently of the individual conscious effort. Christakis and Fowler describe how social networks affect a variety of behaviours and emotional states; happiness, weight gain, back pain, voting and suicide. How do networks influence actions and emotions? Basically through peer pressure and “modeling” a process whereby people mimic each other. Even if your weight gain doesn’t cause your friend to gain weight, it may adjust her idea of what weight is acceptable.
In the same way that birds fly in formation, social networks obey rules of their own, rules that are distinct from the people who form them. “The networks we create have lives of their own. They grow changes, reproduce, survive and die. Things flow and move between them.” Fascinating, seems to undermine all concept of free will.
The book make a compelling case for public policy and health interventions to take heed of social networks in intervention design. Melinda Gates also makes a compelling case for human connection to be a source of inspiration and meaning.
However, harking back to my work in social exclusion, what about those who are poorly networked? The disenfranchised and the poor? There may be some benefits – they will not adopt socially contagious unhealthy behaviours. But the book mostly describes the positive influences of social networks. Research shows that those with more friends are happier, healthier and richer. I think policy interventions also have to spend the time to figure out how to reach the hard-to-reach.
Update: a systematic review was recently published that finds evidence of friends’ influence on weight gain from 16 studies.