"The average American has only two close friends, and a quarter don't have any." Mark Vernon offers this observation in his "USA Today" article, "Is true friendship dying away?" That comment stopped me cold. My first thought was how isolated, how alone being friendless would feel. My second thought followed Vernon's line of research which focuses on friends in the social media age. Is a sense of isolation a driving force behind the explosion of social media usage, or is it a result of our addiction to technology?

Personal pages on social networking sites boast the number of "friends" each person has acquired. The count has become a badge of success, something to tweet about.

Yet, research by British anthropologist Robin Dunbar suggests the size of our brains, specifically the part that processes conscious thought and language, limits "the number of individuals with whom a stable inter-personal relationship can be maintained." Dunbar's theoretical number is 150 people. He identified this number by studying primates and human groups from primitive villages to modern workplaces. Preliminary reports from his current study of social networking sites confirms the 150-person limits of our relationship capacity. One person reported on Answerbag.com that a college friend had over 2,000 Facebook friends but when that person died, "only about 150 people went to her funeral." Hmmm. There's that Dunbar number again.

Social media relationships remind me of "pen pals" that were popular in the mid 1900s. Mine was a girl named Marejke who lived in Europe. Our connection was made through an organization that matched students from different countries - the 1950s paper, pen and postage version of social networking. We wrote to each other about our families, our interests, what we were doing in school.

A letter took weeks to travel between Breda, The Netherlands and Evansville, Indiana. I remember my excitement when her letters arrived in the tissue-thin envelopes with matching paper we used to lessen the high cost of overseas mail. The thrill was not in what she wrote but the very idea that I was communicating with someone on the other side of the world.

We kept in touch, though less frequently, into adulthood. Eventually, I had the opportunity to spend an afternoon face-to-face with Marejke. To my surprise, we had little in common and soon ran out of conversation.

Today, technology makes worldwide connections commonplace and response time often immediate. But, are we building relationships with the depth of enduring friendship or merely friendly connections?

Vernon offers an intriguing quote from Aristotle: "Close friends share salt together." This is not about passing the shaker during an eat-and-run meal at a fast food spot. Close friends, Vernon explains, " sit with one another across the course of their lives, sharing its savor - its moments, bitter and sweet."

I have "online friends" with whom I share mutual interests: reading, writing, genealogy, polymer clay. We have connected through membership in organizations related to these interests that host blogs and listserves. We might even meet face-to-face at conferences or over a cup of coffee when we happen to find ourselves in the same city. These connections offer encouragement, sympathy, advice, new ideas, resources for problem solving, a shared laugh.

Then there are "friends online," people with whom I have a deep personal relationship beyond the confines of the computer screen. Some I have known since childhood. Others have been roommates, co-workers, community connections, neighbors. We know each other's strengths and weaknesses, joys and sorrows, hopes and fears. We have a history together and our lives have been seasoned by shared experiences. They are people I "know, like and trust" (the American Heritage dictionary definition of a friend).

Many of us are separated by great distances now. Email has replaced telephone calls and letters we used to exchange by U.S. Postal Service. Today, technology allows us to sit together at a virtual kitchen table, discussing, consoling, encouraging, laughing and crying together. Our friendship has been tested by life's events and found durable. These are the people who would come if I needed help and they know I would do the same for them. These are the real friends with whom I share digital salt.

Cynthia Becker is a past Colorado Voices writer from Pueblo who blogs at http://chipeta.wordpress.com but has so far avoided a Facebook page. EDITOR'S NOTE: This is an online-only column and has not been edited.