by Brian L. Grant MD

This fascinating article describes the size of social networks that societies generally adapt.

I was struck by how accurate it was in my life, comparing my own holiday card tradition with the experiment cited by the author. In his case, the average number of cards sent out by individuals was about 150.

In recent years, I have engaged in an annual ritual of sending a holiday card to a number of people, hand addressing the envelopes and using a real stamp – a very analog task in my otherwise digital world. How many did I send this past year?

About 150 plus or minus 10%. These comprise of family, close friends and acquaintances, a few colleagues and some closer co-workers. It is a small subset of the many people that I know. But as the article states, they likely comprise a good portion of the people I would feel comfortable having an impromptu drink with.

It appears that 150 is a size that many groups limit themselves to for a variety of purposes. Facebook, which I rarely use at any meaningful level, lists that I have 274 “friends,” and I have 572 “connections” on Linked In, many of whom I accepted an invitation from, but I would not know if they walked up to me.

Cognitively, regardless of how far technology may extend us, our ability to relate closely may be limited by our biology.