The networking pioneers
Who should be regarded as the founding fathers of social networking, the phenomenon that now joins hundreds of millions of people in online conversation? Perhaps Mark Zuckerberg who created Facebook in his room at Harvard in 2004? Or maybe Jonathan Abrams who founded Friendster and was all set to become the biggest mover and shaker on the web - until Zuckerberg came along.
In California, where I'm making a radio series about the history of social networking, I've met two people who have a better claim to be pioneers. Both are much older than either Zuckerberg or Abrams and both have their roots in a 1960s culture which saw technology as just one way of changing the world.
My first stop was in Berkeley, the cradle of the counterculture, where I had come to meet Lee Felsenstein. He had studied here in the 1960s and had been swept up in, what he described to me as, the revolution that spread from the University of California campus across America. That revolution, he explained, had built a powerful community in and around Berkeley, and he had been determined to use his skills as a computer scientist to keep that spirit alive.
We met outside a scruffy fast-food joint in the student quarter because this was the birthplace of Community Memory, the first real attempt to build an online meeting-place. In 1973 in Leopold's Record Store, which stood on this site, Felsensetin and a few colleagues installed their project's first machine.
"They had a musicians' bulletin board at the top of the stairs so we put it next to that," he explained. "We had a teletype terminal in a cardboard box I built. It had a clear vinyl cover so you could see what was being typed. "
Anyone coming up the stairs was invited to come and use the terminal to write a message.
"We thought there would be considerable resistance to the idea of computers invading the counterculture ," Lee Felsenstein told me. "We were wrong. One of us would stand by the terminal and invite people to use the computer. At that point their eyes would brighten up and they'd say 'Oh wow can I really use it?'"
Many of the musicians were soon abandoning the paper bulletin board and moving to the computerised version. But there were other users of Community Memory too, from a poet coming to type a couple of verses to promote his wares, to people seeking apartments or cars.
"We did not constrain the topics that items were indexed by," Mr Felsenstein explained. "When you wrote something you were told to think of a word that someone might use to find this item."
Thirty five years before Twitter took off, it seems the idea of hashtags to connect conversations was taking off at Leopold's Records.
The project went through various ups and downs, dying and then being reborn a couple of times, but survived into the early 1990s, when there were 10 terminals dotted around the San Francisco area for anyone to use.
I explained to Lee Felsenstein the idea of the blue plaque that we put on British buildings of historical significance and asked him what a plaque mounted on this site might say. He came up with this:
"Here in 1973 was opened the first public access computer system for use by people with no familiarity with technology. The door to cyberspace was opened here for the first time and it was found to be hospitable territory."
My next stop was at the Skoll Global Threats Fund in San Francisco, where Dr Larry Brilliant continues his lifetime's work as a doctor battling against diseases such as polio and smallpox. But we'd come to hear the story of how he co-founded an online community called The Well in 1985.
The Well, or Whole Earth 'Lectronic Link, built an online community of 50,000 people in the San Francisco area years before the web was created. Its guiding genius, as Dr Brilliant was keen to stress, was Stuart Brand, who I'm meeting later this week.
But Larry Brilliant had a fascinating tale to tell about the technology behind this community. The story began when a helicopter vital to a public health project the doctor was running in the early 80s crashed in the Himalayas. "We needed to find a way to get it a new engine in a hurry," he explained. Using contacts in Silicon Valley he managed to set up what may have been the world's first internet tele-conference, bringing together charitable backers in the United States, the engine maker at France's Aerospatiale and the US ambassador in India.
The result was that 36 hours later a new engine was on its way to the Himalayas. Larry Brilliant returned home to the United States, where he was a professor of public health, and told this story to an old friend. That friend was Steve Jobs, who had supplied a very early Apple computer to the Asian health project. "Steve told me I ought to turn the idea into a business. I didn't really know what a business was back then."
But he forged ahead with the online communications project and took the idea to Stuart Brand, whose Whole Earth Catalogue was already a counterculture hit, listing all kinds of products for people interested in sustainable living. The Well was born out of that meeting, and seven other online communities also used the technology, though none with the same success.
The Well went on to provide more inspiring stories of the power of online communication, as its members used its forums to share their lives, their thoughts, and their passions - whether it be for obscure technology questions or discussions about the meaning of life..
I asked Dr Brilliant, as I'm asking everyone I'm interviewing for my radio series, how social networking had shaped his life. "In every conceivable way," he said, explaining how his career which has included a spell running Google's philanthropic arm had continually involved people he'd met through this early social network. "When I go to Silicon Valley I meet people whose companies or ideas got started on The Well, either as participants or observers. Every step I took after The Well was shaped by it."
These two founding fathers of online communities had one delightful and surprising characteristic in common. Both Lee Felsenstein and Larry Brilliant, while nostalgic for those pioneering days in the 70s and 80s, refused to be curmudgeonly about the modern networking world.
Despite coming from a counterculture that greeted the first adverts on the internet with outrage - apparently it was two lawyers spamming fellow members of an early bulletin board - they were both enthusiasts for Facebook and Twitter, which depend on advertising for their futures.
But then again why should I be surprised? Each man had a vision of a future where technology could both strengthen and enrich the ties between us. Now, ever so gradually, they see that beginning to happen.