That's largely thanks to Facebook itself, of course, as well as other modern social networks.
"When considering even the most distant Facebook user in the Siberian tundra or the Peruvian rainforest, a friend of your friend probably knows a friend of their friend," wrote the Facebook data team in a blog post explaining its research.
The idea that only a handful of people separate all folks on Earth was popularized by John Guare's early 90s play "Six Degrees of Separation," which was turned into the 1993 film of the same name. But you may know it instead from the popular game "six degrees of Kevin Bacon," in which players attempt to link random actors to Bacon through films the two starred in.
That number used to be six. But thanks to the increasing popularity of social networking, humanity has become more connected over time. Where in 2008 the distance from any one Facebook user was, on average, 5.28 hops, it’s now 4.74, the company's researchers said.
Plus, Facebook users are highly likely to friend people like themselves — that is, in their country and of their age. So if you take two people within a country, there’s likely to be only three degrees of separation between them.
Also interesting: Only half of Facebook users have more than 100 friends.
"At first glance, the median friend count on Facebook — 100 — may seem surprisingly low; a quick survey of my own friends reveals that they almost all have more than 100 friends," the team wrote.
That's a sociological phenomenon that's well documented, in fact.
"These effects all arise because for people, classes, and flights to be popular, you must be much more likely to choose them. So you shouldn’t feel bad if it seems like all your friends are more popular than you: it appears this way to most of us."