From 7 to 3 degrees of separation

In 1969 Jeffrey Travers and Stanley Milgam conducted an experiment on degrees of separation between people. You all have heard about the results: human beings are separated by 6 degrees of acquaintances.

Some forty years later Leskovec and Horvitz (2007), both from the Microsoft Research center, concluded that human beings were separated by 7 degrees of acquaintances.

6 or 7 links between Human beings ?

The difference comes from a less known fact : Travers and Milgam’s conclusions were based on a sample of 296 people in Nebraska and Boston; a relatively small sample indeed. Leskovec and Horvitz analyzed 30 billion conversations among 240 millions people. That’s what we call Big Data. The result is a better precision and a better confidence regarding the results. If we want to turn a little bit technical you may note that Travers and Milgam mentioned in their 1969 paper that one sample had a 6.1 links distribution while the other was 4.6. Leskovec and Horvitz concluded on an average 6.6 links distribution.

3.5 links only in 2016 !

Something incredible happened in September 2006 : Facebook. Suddenly we became much more connected to each other. And the result of this increased connectivity was presented on 4 February 2016 by the Facebook Research department. And guess what … the average number of links has dropped to only 3.5 !

Conclusion 

The first thing we can say is that between 1969 and 2007, processing Big Data has allowed to improve precision on the number of degrees of separation between Human beings. Those degrees of separation were subsequently dramatically lowered by Facebook which increased the connectivity between Humans.