Have you ever gotten a job referral from a friend of a friend? Most likely. It’s bound to happen in our world of over 7.2 billion. From the cell phone to the internet, our capacity to reach out others through technology has redefined social networking.

While humans now have an unprecedented ability to connect, human social circles haven’t evolved as much as you many think. We all acknowledge that clicking the “accept” button to a friend request on Facebook doesn’t carry the same sentiments as grabbing coffee with an old friend. The limits of human relationships still persist.

 How small is our “small world”?

Right now, you are approximately six degrees of separation from anyone in the world. In 1967, Stanley Milgram (best known for his Shock Test) and Jeffrey Travers published their “The Small World Experiment”  in Psychology Today. In their experiment, Milgram and Travers analyzed how many hands a letter, beginning in Nebraska, would pass through before being delivered to its target recipient in Massachusetts. What’s the catch, you ask? Individuals along the chain were only allowed to send letters directly to someone they personally knew.

Milgram and Travers found the average number of intermediaries in completed chains was 5.2 (but let’s round up to 6.0– 0.2 of a person isn’t going to do anyone any good). The media came to popularize the phrase “six degrees of separations” based off of their research, even though it was never directly stated in their work.

How big is my first degree social circle?

Let’s be honest. The likelihood of discovering your connection with a sixth degree acquaintance is small and, frankly, unnecessary. However, knowing the magic number of first degree connections will be of interest to you. It’s 150.

This number, known as Dunbar’s Number, was calculated by British anthropologist and evolutionary psychologist Robin Dunbar in the 1990s. Dunbar studied the correlation between primate brain size and average social group size. Using this data, Dunbar estimated that humans, due to our the size of our neocortex, can only comfortably maintain 150 stable relationships.

Dunbar explains the number 150 “refers to those people with whom you have a personalized relationship, one that is reciprocal and based around general obligations of trust and reciprocity.” Simply put, “It’s the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar.” Dunbar’s seminal work has been of critical importance in today’s social network development.

The Sweet Spot: Just outside the 150

So what’s so special about our second degree connections? In the early 1970s, American sociologist Mark Granovetter interviewed 282 men about the path to their current employment. Granovetter was shocked not by Milgram (thankfully), but by the frequent references of casual acquaintances, which he called “weak-ties” in each man’s job hunt.

Granvetter concluded that these so called “weak-ties” were indispensable as they provided access to social networks (jobs, events, news) to which one would not otherswise belong. When second degree connections are included, our social network swiftly bounds from a meager 150 all the way to 22,500. (For all of you rocket scientists out there, that’s 150×150.) Now just to draft that email…

Not just important for the professional setting

Social networks aren’t just about getting jobs. Our connections, regardless of degrees of separation, are the fabrics of the shared human experience. In his best-selling novel, The Power of Habit, Charles Dugill calls upon the critical role of human networks in the development of social movements.

Dugill notes that Rosa Parks wasn’t the first black passenger arrested for breaking segregation laws on buses in Montgomery. Instead, he keys in on Parks’s engagement in her community. From her post as secretary of her local NAACP chapter to her involvement with the botanical club, “Parks’s many friendships cut racial and economic ties.”

Thus, when she was arrested, Parks’s friends, “from field hands to college professors,” responded…and so did their friends. Person by person, a movement formed, thus embedding a new meaning of the word “equality” into American culture and society.

Graduating from this article

As a final note, we’ll travel back to the University of Texas Austin for the Class of 2014 Graduation Ceremony. Recounting ten anecdotal life lessons from his time in basic Navy SEAL training, Admiral William H. McRaven’s commencement address is truly worth the listen. However, if you don’t have the time, you’ll at least have his parting message:

Addressing the graduating class of 8,000, Admiral McRaven’s calculated message is simple, “If every one of you changed the lives of just ten people—and each one of those folks changed the lives of another ten people—just ten—then in five generations—125 years—the Class of 2014 will have changed the lives of 800 million people. 800 million people—think of it—over twice the population of the United States. Go one more generation and you can change the entire population of the world—8 billion people.”

Maybe it’s all just math, but I’d say this world’s truly at your fingertips.