Nicholas Christakis
Physician & Social Scientist, Harvard

How Networks Shape Our Decisions And Our Lives

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When people are free to choose anything they want, they usually choose what their friends have chosen, says internist and sociologist Nicholas Christakis. Mimicry is a fundamental part of human experience. Here's why.

Nicholas Christakis

Nicholas A. Christakis, M.D., M.P.H., Ph.D., is an internist and social scientist who conducts research on social factors that affect health, health care, and longevity. He is a Professor of Sociology in the Department of Sociology in the Harvard Faculty of Arts and Sciences; Professor of Medical Sociology in the Department of Health Care Policy at Harvard Medical School; and Professor of Medicine in the Department of Medicine at Harvard Medical School.

Dr. Christakis' current work is principally concerned with health and social networks, and specifically with how ill health, disability, health behavior, health care, and death in one person can influence the same phenomena in a person's social network. Most recently, Dr. Christakis has been exploring the joint genetic and socio-environmental determinants of the formation and operation of human social networks. His 2009 book, co-authored with James H. Fowler and published by Little, Brown and Company, is called "Connected: The Surprising Power of Our Social Networks and How They Shape Our Lives."

Follow him on Twitter @NAChristakis


Nicholas Christakis: There’s a sort of a funny saying, which is that whenever people are free to choose anything they want, they usually choose what their friends have chosen.  This mimicry that we humans evince is extremely fundamental.  Therefore, networks provide us a kind of mathematical, social and biological tool to understand the kind of fundamental basis for this mimicry because you copy the people to whom you are connected primarily and you come to copy them along a whole variety of traits.  In the workplace these traits might include things like how energized you are at work or how innovative you are at work or how cooperative you are at work or whether you smoke or not or other health traits.  All these desirable properties -- your productivity, your innovativeness, your cooperativeness, your health -- come to depend upon the like attributes in individuals to whom you're connected. 

Our group and other groups have mapped networks in the workplace, have come to understand how people are connected to each other and have used that understanding as a kind of mechanism or tool, an opportunity for intervention, in order to call forth from people better behavior, if you will, more cooperativeness, more innovativeness, more collaborative-ness and better health behaviors.  

The usual way of understanding workplace organization is the classic org chart where you have boxes and names and it's like a tree, but actually the real work or the real organization of a workplace looks nothing like that.  It's the way people interact with each other.  It's a more jumble of ties.  It looks more like a jumble of Christmas tree lights.  So if you can think of a network as every node, every person is a little light and the wires connecting them are the ties between them, and when you take out a jumble of Christmas tree lights and you put it on the floor and look at it, actually that's what workplace networks really look like.  

Once you understand those patterns of interactions you can begin to understand how people influence each other with respect to health and health behaviors in the workplace, and once you understand that pattern of interactions and that pattern of influence you can begin to think about ways of intervening in it.  For example, you can identify influential individuals within the network and target them with health interventions or you can identify ways to get groups of people to sign up for interventions.  And we know that when groups of people, particularly people who know each other and are interconnected collaboratively, engage in something such as a health improvement behavior that they're more likely to sustain it and more likely to respond positively.

So once you understand the structure of human interactions it opens up all kinds of new vistas, new ways that you can intervene.  In fact, it's not just relevant when it comes to health—in fact, it's not just relevant when it comes to health to understand the network of interactions of, let's say, lay people or workers or regular old people.  It's also important to understand the pattern of interactions among healthcare providers. 

Directed / Produced by Jonathan Fowler & Elizabeth Rodd