BROOKE GLADSTONE: In recent times, scientists of various types have tried tracking human social interaction, but people move in mysterious ways. Then came Friendster.com. Friendster is like putting a radio tag on a spotted owl. The social networks of human beings can now be mapped. That of course is just a side benefit. Friendster was conceived as a way to make friends. Each user has a personal network, and inviting friends into that network is as simple as finding someone you like, clicking on their profile and sending them an electronic invitation -- provided they're already connected to someone in your network. If they click yes, your networks are pooled, creating an even larger network. Jad Abumrad takes a look. [SOUND OF COMPUTER KEYBOARD CLICKING]

JAD ABUMRAD: This is the sound of my friend Amy hitting the "Enter" key on her computer.

AMY: Enter -- over and over again.

JAD ABUMRAD: She's been doing it for about 15 minutes. There are thousands of people like her elsewhere in the world doing it too -- trying to log onto Friendster.com which is why they're all getting this message.

AMY: It says "Friendster is temporarily unavailable. Please check back this evening. We apologize for the inconvenience."

JAD ABUMRAD: Founder Jonathan Abrams can only shrug.

JONATHAN ABRAMS: Well the growth we've received in the last few months has been crazy, and what people may not realize is that Friendster has been, you know, me and a couple engineer friends out of our living room up until pretty recently.

JAD ABUMRAD: They're up to 7 employees now. That's roughly one staff person for every 130,000 users --almost a million in total -- and this, says Jonathan is without any advertising.

JONATHAN ABRAMS: You know it started growing virally from the minute I put up the earliest prototype.

JAD ABUMRAD: All he had to do, he says, was send the prototype to a friend who sent it to another friend and so on and so on until word of Friendster eventually infected Amy--

AMY: Yaaaaayyyyy!!!

JAD ABUMRAD: -- who, after an hour of trying, finally breaks through the gridlock.

AMY: I have 17 friends, which is kind of low, by some Friendster standards, but my friends and I decided that-- anybody with more than 50 friends is a "Friendster slut." [LAUGHS]

JAD ABUMRAD: We're now looking at her personal Friendster page. Amy's picture is there along with thumbnail photos of her 17 friends--

AMY: Carla, Phutan [sp?], Mary, David...

JAD ABUMRAD: Clicking on any of their photos takes her to their Friendster page, and from there she can link to their friends and from there to their friends' friends--

AMY: I just-- I kind of browse.

JAD ABUMRAD: -- and with still one more click to friends four times removed.

AMY: You know, it's like the total safest way of browsing singles in New York.

JAD ABUMRAD: Safe, she figures, because they're all connected to her -- somehow. Friendster in fact plots out the connection at the top of each single guy profile she visits.

AMY: He's friends with my friend Lily who's friends with Jason who's friends with Sarah who's friends with him.

JAD ABUMRAD: Oh, so that's four degrees, right?

AMY: Yep.

JAD ABUMRAD: And that is where Friendster draws the line --at four degrees. Still-- when taken out that far, Amy's immediate 17 buddies add up to a social network large enough to fill Madison Square Garden.

AMY: 82,695 people in my network. [SPRIGHTLY RENDITION OF EXCEPT FROM SONG: "IT'S A SMALL WORLD AFTER ALL" UP AND UNDER]

JAD ABUMRAD: On Friendster, Amy isn't just an anonymous individual. She's a star in her own constellation -- in a whole universe of other constellations. She's basically at the center of her own Kevin Bacon game. Friendster and Kevin Bacon owe a debt of gratitude to a 1967 experiment called The Small World Project. Here's what happened. Psychologist Stanley Milgram chose a guy in Boston and then asked 300 strangers to relay him a package.

DUNCAN WATTS: So, you know, many of them did this, and they sent it on to their friends and their friends got the same set of instructions and sent it on to their friends and so on.

JAD ABUMRAD: And eventually, says Sociologist Duncan Watts, 60 of Milgram's 300 packages reached the target, getting there in an average of 6 steps.

DUNCAN WATTS: He never used the phrase "six degrees of separation," by the way; that was coined by the, the playwright John Guare.

JAD ABUMRAD: Nonetheless that phrase stuck. Duncan even chose it as the title for his recent book. He and his colleagues at Columbia University in New York are repeating the Small World Project, this time on the internet. They're asking thousands to pass on an e-mail to a target, and they're collecting reams of data in the process. With that data, Duncan hopes to test one of Milgram's more controversial claims -- that there are certain people in any social network who function like hubs. They've been called "mavens," even "opinion-leaders."

DUNCAN WATTS: And Milgram called these guys "socio-metric stars."

JAD ABUMRAD: Which describes how these nodal folks might look if you mapped the social network they're a part of. They'd be the points with lots and lots of spokes coming out.

DUNCAN WATTS: But it also can be interpreted as, you know, the guy's a bit of a star.

JAD ABUMRAD: The socio-metric star in Milgram's case was a tailor. Of the 60 packages that made it to his target person, 7 got there through this one guy. Duncan Watts and his team say they haven't yet found evidence of socio-metric stars in their repeat experiment, but on Friendster, where adding friends is as easy as clicking a hyperlink, evidence abounds. Take guys like Jordan. [COMPUTER KEYBOARD CLICKING]

JORDAN: [READING] Friendster is temporarily unavailable.

JAD ABUMRAD: Big shocker there.

JORDAN: As usual.

JAD ABUMRAD: Now Jordan is one of those people who seems to know everyone -- everywhere he goes -- and when we finally make it to his Friendster page--

JORDAN: This is my profile picture.

JAD ABUMRAD: I find out that he has an extended social network the size of a small city.

JAD ABUMRAD: Jesus!-- God! You're connected to 239,365?!

JORDAN: That's right. [LAUGHS]

JAD ABUMRAD: How the hell--?!

JORDAN: See this is what's been freaking me out about Friendster. [LAUGHS] I think when you get into a certain point, you know, when you have enough friends, then you're just like accessible to enough people that it snowballs and then anybody can find you and they do --cause, you know, I'm getting messages from like high school people that I haven't talked to in years.

JAD ABUMRAD: There is a reason he hasn't talked to them in years -- because he doesn't like them.

JORDAN: I just -- I always accept friendships cause I feel like it'd be too rude. [LAUGHS]

JAD ABUMRAD: This may be one of the tradeoffs in a world where everyone can access everyone. See, Jordan is a victim to what sociologists call "the familiar stranger phenomenon" - which is this: often in our daily routine we'll see the same people every day, like on the subway, and we won't say anything to them -- because they're strangers, and it would be strange to say anything. But if we see these same people in, say, Spain, we're like -- "Hey! How's it going?!" And Friendster may be just enough of a new environment to bring out all the familiar strangers in Jordan's life, which is bringing him down.

JORDAN: It starts to take up your time. If you, like, feel obliged to respond to every message--

JAD ABUMRAD: Which he says he does, and that's why he's considering committing Friendster-suicide --removing his profile all together. Meanwhile the site continues to add 20 percent more users each week, and within two months Jonathan Abrams says they'll begin to charge, and within a few years, some predict Friendster will make yet another leap -- off the desktop and into the real world. Sociologist Howard Rheingold [sp?] thinks so. In his book Smart Mobs he imagines what may happen when social networking and mobile technology intersect.

HOWARD RHEINGOLD: Maybe you can walk down the street and say to your telephone: Is there someone who's, who's offering a ride in exactly the direction I'm going right now and - or might be interested in a date on Saturday night or "Who here in this coffee shop likes Six Feet Under?"

JAD ABUMRAD: Perhaps as foreshadowing to a time when that will be true, with just one click, my friend Amy shows me all the people in her network who like the TV show Six Feet Under.

JAD ABUMRAD: Wow! 6,884 people.

AMY: Mm-hm. That's cool!

JAD ABUMRAD: It is cool -- if you think about it. She may have just cut through years of seedy bar talk to find 7,000 friends of friends who at the very least have the same taste in TV as her, and with another click she could easily locate fans of her favorite band, the Shins, or The Intuitionist, her favorite book, or all those who like boats and live in Brooklyn and vote Democrat and believe in God and a woman's right to choose. Friendster and the Small World Project are slowly leading us toward the answer of how we connect, but we may never know why. Only that we do need to. And where there is a will [COMPUTER KEYBOARD CLICKING] and the web site, there is a way. Usually.

AMY: Usually you get on after a couple tries. [INTRO TO "SMALL WORLD"]

JAD ABUMRAD: For On the Media, I'm Jad Abumrad.

AMY: It's so annoying! [EXCERPT FROM CHORUS SINGING "SMALL WORLD"]

CHORUS: IT'S A WORLD OF LAUGHTER, A WORLD OF PEACE--

BROOKE GLADSTONE: Coming up, a look back at the Summer of '73 --the lasting legacy of a televised scandal called Watergate.

CHORUS: --IT'S A SMALL WORLD AFTER ALL!

BROOKE GLADSTONE: This is On the Media from NPR.