Have you ever heard of “Dunbar’s Number”? Discovered by British evolutionary anthropologist Robin Dunbar, it is the human norm that the number of genuinely personal relationships a person can actively maintain is 150, give or take. Dunbar and his colleagues note that “150 people is both the approximate size of a typical small-scale human village and about the number of people who can live or work together without needing power structures to enforce cooperation. The group is small enough that social pressures can keep people in line” (“Does Your Pastor Need a Friend?” Christianity Today, October 2017, p. 62).
I find this interesting because at a recent conference I attended, the keynote speaker said that currently a majority of congregations in America have an average weekly attendance of guess what? 150 members.
It occurs to me that this is not simply a coincidence. 150 appears to be the sweet spot for most churches for the very reasons that research for Dumbar’s Number indicates:
It keeps the group manageable. People do not become just a number. People know them by name. Functions can happen without an overflow of people and not in an oversize room.
It keeps the group personal. Everybody knows each other and can keep relationships functioning. People care about one another because they know them well and see them often.
It keeps the group accountable. People notice when others are missing and can follow up with them. People can see when fellow members are straying and can bring them back into the fold. There is a sense that people are expected to be present at certain times and be there for one another in times of need.