Six Degrees of Separation

“Six degrees of separation. Between us and everybody else on this planet. The President of the United States. A gondolier in Venice. Fill in the names,” John Guare wrote in his play, Six Degrees of Separation. In an increasingly interconnected world, does the “six degrees of separation” rule hold up to scrutiny?


The six degrees of separation theory first became popular in the mid-20th century. It started with a simple short story written by Hungarian writer Frigyes Karinthy in 1929. In the story, the characters play a game in which “we should select any person from the 1.5 billion inhabitants of the Earth…using no more than five individuals, one of whom is a personal acquaintance, he could contact the selected individual using nothing except the network of personal acquaintances.”

The game in the story caught the attention of academics; could the phenomenon be true?

Sociologists, mathematicians, and computer scientists have attempted several experiments among various populations. The most prominent study was by Stanley Milgram in the late 1960s, when he attempted to solve what he called the “small world problem.”

A hand holds a small model of Earth.

It’s a small world after all. Photo: Ponsulak/Shutterstock


At random, Milgram selected ‘starters’ living in Wichita, Kansas, and Omaha, Nebraska. Their task was to mail an envelope to a ‘target’ in Boston. Milgram sent 60 envelopes to the starters. If the starters knew the target personally, they would send the envelope directly. If not, they passed the envelope to someone they believed was more likely to know the target.

Unfortunately, the study did not have the desired effect. It had several flaws, including people disinterested in participating and lost envelopes. According to writer Dave Roos, the experiment had a 5% success rate; only three envelopes made it to their intended targets.

More recent studies have tried the experiment using computers. In 2001, Columbia University professor Duncan Watts used Milgram’s experiment as a model but instead gathered data using email chains. This study found the number of intermediaries required to get to a target was six!

Between 2007 and 2008, Microsoft researchers Eric Horvitz and Jure Leskovec found that 240 million people were connected by approximately 6.6 degrees. They came to this conclusion by analyzing electronic mail and conversations. “To me, it was pretty shocking. What we’re seeing suggests there may be a social connectivity constant for humanity. People have had this suspicion that we are really close. But we are showing on a very large scale that this idea goes beyond folklore,” Horvitz told The Guardian.

In 2016, Facebook acknowledged that its users are typically connected by three or four degrees. LinkedIn has a feature that shows first, second, and third-degree connections.

Pop culture

Recently, the theory gained considerable attention because of actor Kevin Bacon. Six Degrees of Kevin Bacon is based on the idea that every actor in Hollywood is connected to him. The game is simple, find an actor and start a chain link connecting them to Bacon.

Six degrees of Kevin Bacon.

Six Degrees of Kevin Bacon. Photo: The Oracle of Bacon



The reality of separation by six degrees is becoming more evident in our Digital Age. Facebook and LinkedIn in particular showcase just how interconnected we are. Social media has played a key role in connecting us at great distances and with the emergence of new networking apps, these gaps may continue to shrink.

So, what mind-blowing connections do you have?

Kristine De Abreu

Kristine De Abreu is a writer at ExplorersWeb.

Kristine has been writing about Science, Mysteries and History for 4+ years. Prior to that, Kristine studied at the University of Leicester in the UK.

Based in Port-of-Spain, Kristine is also a literature teacher, avid reader, hiker, occasional photographer, an animal lover and shameless ramen addict.