Dunbar’s number, the Allen curve, and why organization size matters / by Paul Gambill

I had the good fortune of beginning my professional career at a company of about 160 people, spread over two offices. There were 120 people in my office when I started. Fortunately for me, that was just about the optimal size of a social group, also known as Dunbar’s number

About 20 years ago, an anthropologist named Robin Dunbar observed that there was a correlation between the size of a primate’s brain, and the typical size of a social group. Extrapolating that out to humans, he arrived at a number of ~150 as the maximum number of strong relationship ties your brain can hold. This has been confirmed through research and empirical observation of groups such as ancient Roman military company sizes and traditional hunter-gatherer tribes.

There is another relevant rule from social research called the Allen curve. This is a “rule” that as distance increases between two colleagues, their frequency of communication decreases exponentially. Because of the Allen curve, I had almost no communication with the 40 people in our other office in Denver.

That office size of 120 was nearly ideal. I knew almost everyone (consider that 150 is the limit for an individual. I certainly had more ties to people outside of work, so it’s doubtful I could have had strong ties to all of my coworkers) and we all shared in a common vision and mission for the company. 

That all changed when we were acquired by a mega-consulting firm that employs over 70,000 people nationwide. Our ties broke down, people left, and ultimately the company I had admired disintegrated. 

I learned a very strong lesson from that experience, and that is that organization size matters a great deal. It is incredibly difficult to maintain strong ties in a large corporation with many different divisions and locations. Certain economies of scale can only happen in larger organizations, but I don’t believe the trade off is worth it all that often.