Here's a fun question in the age of social networking, Facebook, Twitter, and Instagram: how many meaningful relationships with people can the average person have? The answer: about 150. This number was derived from the research of British psychologist and researcher, Robin Dunbar. This research has been coined “the Dunbar number.” This week's issue of Bloomberg Businessweek magazine (Jan.14-21, 2013) has a nice, concise write-up about Dunbar's studies, and how they apply to most of us, written by Drake Bennett.

Dunbar grew up in Tanzania, and has an academic career in England, where he teaches at Oxford. He began his research career studying the behavior of monkeys. He found that primates’ behavior changed based on the size of their social group. The larger the size of their social group, the more they seemed to exhibit behaviors to be seen favorably by other members of the group. 

Dunbar went on to study brain size and look at the advantages and complications of animals that evolved into having larger brains. The complications of large social groups include competition for resources, like food, as well as the data that must be processed about the relative hierarchies and relationships with all the others in the social group. Dunbar’s research eventually led him to hypothesize that larger brains (and therefore higher intelligence) led to the development of larger social groups. 

However, even the smartest primates have limits!  While there are individual variances for personality, and particularly extroversion/introversion, Dunbar theorizes that for most human beings, the limit of meaningful relationships a person can have is 147.8. In the Bloomberg story, Dunbar deftly describes that number as “the number of people you would not feel embarrassed about joining uninvited for a drink if you bumped into them at a bar.”

Dunbar networks with his colleagues in a wide variety of disciplines to focus on the social brain hypothesis, including linguists, computer scientists, physicists, classicists, economists, archeologists, anthropologists, and literary scholars. He's spoken at TED conferences, and written several books for non-academics, including The Science of Love (2012).

Dunbar has been invited to consult with a former Facebook executive, who left to co-found Path, a mobile photo-sharing and messaging service, which began in 2010. After consulting with Dunbar, Path founders decided to limit their site’s users to 150 friends. Basically, Dunbar suggests that we, as humans, have an upper limit in the number of meaningful social relationships we can have, and beyond that is something else— perhaps marketing, or acquaintances, but probably not meaningful relationships. Dunbar recognized this pattern of 150-person limits across the world—many companies, clans, and even military units are often capped at 150.

No matter how technology expands, human beings have a finite number of intimate and meaningful relationships. Digital technology doesn't change the fundamentals of our biology and neocortex. I found it interesting that Dunbar, although well-liked by colleagues across disciplines, considers himself on the shy side. He doesn't use Facebook or Path, and says he got a LinkedIn account only by mistake.

Dunbar's research actually suggests other numbers as well. Most people, he believes, have an innermost circle of 3 to 5 people. The next circle has 12 to 15, and their loss would be difficult for us.

I found it interesting that Dunbar believes most friendships can survive only 6 to 12 months without face-to face contact. His research suggests that women can have 2 best friends, including her romantic partner, while most men have only one.

Dunbar's research has critics, but I found the Bloomberg article by Drake Bennett great food for thought and discussion about social networking, genuine intimacy, and the gaps between the two. It’s fascinating that Facebook allows 5,000 friends. Or maybe that’s just acquaintances.