Six degrees of separation may be good enough for most people, but for Facebook members, it's only 4.74 degrees, according to a study conducted jointly by the social networking giant and the University of Milan.
Conducted earlier this year, the study examined all 721 million active Facebook users, who had 69 billion friendships among them, Facebook said.
Whether the conclusions of the study might be off-base is open to debate.
"Obviously the study is only valid for the part of the population that is on Facebook," James H. Fowler, professor of medical genetics and political science at the University of California at San Diego, told TechNewsWorld.
"But increasingly that population looks a lot like the population as a whole," Fowler added.
"The data is skewed," stated Lon Safko, social media entrepreneur and consultant, and coauthor of The Social Media Bible.
"We're talking [in the survey] about like-minded people with common areas of interest," Safko told TechNewsWorld.
I Think I'll Friend You
The researchers conducting the University of Milan/Facebook study approximated the number of hops between all pairs of individuals on Facebook using algorithms developed by the University of Milan's Laboratory for Web algorithmics.
They found that 99.6 percent of all pairs of users are connected by six hops -- five degrees of separation -- but 92 percent are connected by only five hops, which works out to four degrees of separation.
That makes the average 4.74 hops, compared with the 5.28 hops recorded in 2008.
The reason is the growth in Facebook membership worldwide, which ties together even more people.
The researchers also found that a user's friends are most likely to be in the same age group and come from the same country.
Most pairs of people in any one country, the researchers found, are separated only by four hops -- three degrees of separation. Further, 84 percent of all connections are between users in the same country, people tend to have nearly the same number of friends as their neighbors, and they tended to be about the same age.
You can see the researchers' comments on the anatomy of the Facebook social graph here and on four degrees of separation here.
Are We the World?
One of the objections that might be raised about the findings of the study is that it looked at people with similar interests. By definition, all members of Facebook have similar interests at a very basic level. Just by having joined the social network, they're all interested in Facebook to a certain extent.
They may then separate out into groups with other interests, but people tend to cluster together based on their common interests. Thus, someone with an interest in technology and art would have friends in both areas, for example, but none among people whose only interest is history unless they have other interests in common such as, perhaps living in the same neighborhood.
Did Facebook pair up members at random when conducting the study, or did it pair up people with similar interests or of a similar social stratum?
What about location? Would it take a Fortune 500 company executive who was born and raised on the East Coast of the United States and works there six or fewer hops to connect with a prisoner in Guantanamo or a homeless man dying of AIDS in rural Louisiana who has no education or access to modern communications and has remained in the same community all his life?
"Clearly people in very different social circumstances will be less likely to be closely connected," UC San Diego's Fowler commented. "But the average reported takes that into account. If we excluded the path from the CEO to Guantanamo or rural Louisiana, which might be closer than you think, then their measure would very likely have been much lower." 
