Around 2009, Dutch scientist Mollenhurst published a seven-year long study about friendships. The headline of that study that was published around the web was that the average half-life of a friendship was found to be about 7 years. The details of the study, from LiveScience, were:
He conducted a survey of 1,007 people ages 18 to 65, and then contacted the participants seven years later. From the original group, 604 people were re-interviewed. The survey contained questions such as: Who do you talk with, regarding personal issues? Who helps you with DIY in your home? Who do you pop by to see? Where did you get to know that person? And where do you meet that person now? The results showed that personal network sizes remained stable, but that many members of the network were new. About 30 percent of discussion partners and practical helpers had the same position in a typical subject’s network seven years later. And only 48 percent were still part of the network.
There’s a certain similarity to this study and the often-cited and discussed seven year itch in relationships that I find particularly amusing — if for nothing else, the fact that while our intimate relationships are the focus of many discussions and studies, it’s these wider social networks that can have a bigger impact on us — and change more based on context and life circumstance.
There’s a theory out there called Dunbar’s Number that theorizes that the human brain can generally handle between 100 and 250 relationships of any kind. In 1992, British antrhoplogist Robin Dunbar explained it as the number of people that you generally are happy to sit down and have a beer with if you run into them at a bar. Within that around 150 people, he and others that have researched this number theorize that there’s about 5 people in our most intimate groups, about fifteen very close friends, about 50 close friends, and about 150 people that we consider friends. There’s also a supposed absolute limit of 1500 people that most people could pair a name with a face for.
There are competing numbers, of course, including the Bernard-Killworth media of 231. But it’s especially interesting to pair these two studies — if we generally replace around 50 percent of our social networks every 7 years, that means that around 10 people in our social networks shift from “friend” to “acquaintance” every year.
Of course, that also heavily depends on how you define friendship, how you maintain a social network, and what staying in touch even means. I know for sure that not all of the childhood friends that I still have on Facebook are individuals whom I would immediately sit down with for a beer in a bar — if we would have even recognized one another again without Facebook.
This script may vary from the actual episode transcript.