Last month Professor Nicholas Chistakis (Harvard University) and Associate Professor James Folwer (University of California) published the analysis of their research into the spread of happiness in social networks. This study is one of those rather remarkable pieces of research which followed nearly 5000 individuals for 20 years – 1983 to 2003. Those 5000 individuals were embedded in a larger network of 12,000 people, they had an average of 11 connections to others in the social network and their happiness was assessed every few years using a standard measure.
Christakis and Folwer:


  • A person’s happiness is related to the happiness of their friends, their friends’ friends, and their friends’ friends’ friends—that is, to people well beyond their social horizon.



  • We found that happy people tend to be located in the center of their social networks and to be located in large clusters of other happy people.

  • And we found that each additional happy friend increases a person’s probability of being happy by about 9%. For comparison, having an extra $5,000 in income (in 1984 dollars) increased the probability of being happy by about 2%.

  • We found that social networks have clusters of happy and unhappy people within them that reach out to three degrees of separation.

  • Happiness, in short, is not merely a function of personal experience, but also is a property of groups. Emotions are a collective phenomenon.


As the authors explain we have known for some time that emotional contagion spreads between people through contact, but what this new study shows us that happiness spreads across a diverse array of social ties, over time and distance. The happiness effect reduces the further removed the contact is, but evidence is that three degrees of separation still has an impact on the individual.
A few things struck me in particular about the study:
  • The statistical models suggest that clusters of happiness result from the spread of happiness and not just a tendency for people to associate with similar individuals. So, we really can have a significant impact on the happiness of our friends and family, not just by giving them friendship, but simply by being happy ourselves.
  • Network characteristics independently predict which individuals will be happy years into the future.
  • Although happy people tended to be within a larger network of happier people, I couldn’t find anything specific about whether a happy individual attracts a larger, happier network, or whether the network itself makes an individual happier. I wondered about this particularly because my own experience is that my networks make me happy…

This research project reminded me very much of another longitudinal study which looked at resilience over a 30 year year period (1955-1985) on Kauai, and island of Hawaii. This study had been very important to my own recent studies, and their conclusions shared some characteristics of this latest report. They found that individuals with many strong and diverse social ties where more likely to overcome adversity. Social ties were considered one of the most significant ‘protective factors’.

Wonderful, painstaking, research. And so important to understand how we have so much potential to positively impact those around us…..


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