“Setting an example is not the main means of influencing another, it is the only means.

~ Albert Schweitzer

Through a series of fascinating studies, Harvard-trained social scientists, Nicholas Christakis and James Fowler, have shown that human beings are profoundly influenced by the behavior of the people closest to them in their lives.

When we learn a colleague has voted, for example, we’re far more likely to vote ourselves.  When someone in our social circle quits smoking, eats too much in a restaurant, or is characteristically studious, we’re unconsciously persuaded to copy those same behaviors.

While the research proves something we may long ago have intuitively surmised – that we directly influence our friends and they influence us – Christakis and Fowler discovered that the true nature of that impact is far greater – and wider – than any of us may have imagined.

What you’re about to learn is groundbreaking information (not to mention incredibly interesting).  But it’s very possible that your behavior as a leader will be permanently and positively changed once you discover the full power of your own personal example.

Human Behavior Is Wildly Contagious

In what’s perhaps their most revealing study on influence, the two researchers sought to determine whether having an obese friend made people any more susceptible to becoming obese themselves.

To get their answer, Christakis and Fowler directed a team that painstakingly analyzed three decades of data collected from the famous, and still ongoing, Framingham Heart Study.  Dating back more than 50 years, 15,000 study participants – the residents of Framingham, Massachusetts – have visited their doctors every four years to have their key health indicators, including their weight, measured and recorded.  And before every check-up was finished, participants updated their list of family members, co-workers and friends.

By the time all the analysis was completed, the research team identified how 5,124 of the Framingham residents were connected, and linked them to over 50,000 friends, family and co-workers.

The study results were then published in the New York Times.  In a front-page article titled, “Are Your Friends Making You Fat?” the paper reported that the behavior of loading on pounds is highly contagious:

When a Framingham resident became obese, his or her friends proved to be 57% more likely to become obese as well.”

As stunning of a finding as this was, the research produced two additional discoveries that prove one person’s behavior can spread well beyond their closest contacts:

  • A Framingham resident was roughly 20% more likely to become obese if a friend of a friend gained weight.
  • And, a person’s risk of obesity went up 10% if a friend of a friend of a friend gained weight.

In a book Christakis and Fowler subsequently co-wrote, Connected: The Surprising Power Of Our Social Networks And How They Shape Our Lives, the authors named this phenomena, the “Three Degrees of Influence Rule.”  I recently met with Fowler at the University of California, San Diego (where he’s Professor of Medical Genetics and Political Science), and asked him to explain the finding.

“What we discovered is that everything we do or say tends to ripple though our network, having an impact not just on our friends (first degree), but also on our friend’s friends (second degree) and even our friend’s friend’s friends.  What we rarely consider is that everything each of us thinks, feels, does or says can spread far beyond the people we know.”

As an explanation for why human beings are influenced this way, Fowler and Christakis theorize that people pick up subconscious signals from everyone around them, and then use those clues to define “normal” behavior.  They suspect that as friends around us gain weight, for example, we gradually change our mental picture of what “obese” looks like and permit ourselves to pack on more pounds.

Leveraging This Knowledge To Expand Your Leadership Influence

Since Connected was published, Fowler’s been able to more deeply understand how his and Christakis’ work can greatly improve personal influence.  During our conversation, I asked him if there were specific ways workplace leaders could intentionally leverage his research to build more effective teams, and more cohesively shape their organization’s culture.  Without hesitation, he offered these three insights:

1.   Keep Your Obese Friends

One of the big take-aways from the obesity study, Fowler told me, is that a lot of people concluded it would be wise to dump all their fat friends.  “But we found that people who keep their overweight friends are far healthier than the ones who don’t.  There’s simply tremendous value in having friendships.  Even a dysfunctional one is almost always better than no friendship at all.”

For this very same reason, Fowler stresses that it’s generally a mistake in business to instinctively get rid of employees who behave in ways that compete against the culture.  Just as with having an overweight friend, he says, every worker has value (e.g. skills, talents and know-how) that gets lost when they’re dismissed.  And Fowler is convinced that exposure to the correct conduct is often all that’s required to turn rogue employees around.

“Before you weed somebody out, you should first surround them with people who model the desired behavior,” he advises.  “Organize the people they routinely work with to try to change their behavior before taking any drastic step.”

2.  Use Communications To Inspire

One of the most important lessons from the research is that human beings routinely copy one another, often unconsciously.  So in business, whatever example a leader sets, employees are likely to repeat it.

Consider the following scenario.  A manager sees a report that shows his team is significantly behind goal in a key area.  Feeling stressed, he rushes off an e-mail to his direct reports to convey his dissatisfaction, and brusquely challenges them to ensure the goal gets met by month-end.

What many people don’t consider in these situations, says Fowler, is that whatever tone and manner the leader chooses to use to communicate will inevitably get passed down to the lowest level of their organization (at least three degrees).  Because this leader chose to be chiding in motivating performance, his same style will be emulated throughout his entire team.

Something else that Christakis’ and Fowler’s work validates is that human emotions and moods are highly contagious.  This underscores the fact that the underlying spirit of a leader’s words deeply affects how an entire team is made to feel.  Consequently, Fowler urges leaders to be intentionally uplifting, encouraging – even kind – with all their communications.  “The question I’d have you ask before you push the send button is this: ‘Would I want to be in a company where ten people are sending out messages like this one?’”

3.  Nurture All Your Personal Relationships

As described in Connected, Stanford sociologist, Mark Granovetter, surveyed technical, managerial and professional workers in Boston who recently had relied on personal contacts to get a job.  He discovered that most of these workers found jobs via “weak ties,” old college friends, past workmates, and even previous employers – people no longer in their day-to-day lives. And, in what represents further validation for the “Three Degrees of Influence Rule,” it was distant friends, or friends of friends, who most often passed on their names to hiring managers.

“What our research shows is that social relationships are way more powerful than we realize,” says Fowler.  “Tied to all we’ve learned, it’s become clear that managing relationships (within and outside of one’s own organization) is as important if not more important than anything we do in business today.  Our work proves it’s not just the people you can see; it’s also the people you can’t see.  Consequently, the value of each individual relationship you have is far greater than we’ve ever understood because of the multipliers of scale.”


For anyone in a leadership role, the knowledge that their behavior affects the lives of so many people bears an almost sacred responsibility.

But another key insight to be taken from Christakis and Fowler’s research is that every person on your team also has powerful influence on how their colleagues behave.

Your employees, therefore, should be taught about the network effect.  Ensure they know that when they choose to be supportive, collaborative, encouraging and appreciative to people they work with, those same values will ripple brilliantly through your team and beyond.

“There will be conversations and moments where people are spreading information, and learning about how to behave from one another that’s going to multiply all those individual things you do in a company to make it better,” says Fowler.  “I personally believe it’s a very inspirational message.”

Me, too.

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By Mark C. Crowley

Mark C. Crowley is the author of Lead From The Heart: Transformational Leadership For The 21st Century which has been taught in 11 American universities. He is a global speaker, leadership consultant and thought leader on the topics of workplace culture and employee engagement.