Anthropologist Robin Dunbar is famous for theorizing that our brains have a max cognitive limit to the number of people with whom we can maintain an ongoing social relationship. He called this the Dunbar Number and is typically stated as 150 social connections.
There are actually several tiers of the Dunbar Number as follows:
- Core group – up to 5 people (family)
- Close Group – 15 people (close kinship group)
- Acquaintance Group – 50 people (band of related close kin groups)
- Personal Social Group – 150 people (Dunbar believes is the biggest group of people one Human can have close personal relationships with)
- Clan or similar organizational entity – 450-500 people (cohesive sub tribal unit)
- Tribal Group – 1500 – 2000 people (a tribe)
The relationships that are established in a well functioning Forum should fall into the idea of a Core or Close group in a person’s life. From that, we should expect a healthy Forum size to be between 5-15 people, but we can shrink the range a bit more because of two additional factors:
- Time – A typical Monthly Forum meeting is 3-4 hours long, so having too many people will cause issues with not allowing enough time for each person to share. From my experience working with Forums, 10 is the max number of people allowed within a four hour meeting to allow for all the voices to be heard.
- Diversity – Too few people in a meeting and won’t be a wide enough range of knowledge and experience in which to draw from. Plus, with too few people, it leaves very little room for someone to get sick or not make a meeting. From my experience working with Forums, 6 is the minimum number of people to allow for a depth of knowledge and experience.
Having said all this, for the Forum that we launch and support, we aim to keep the membership between 6-10 people, with 8 people being the sweet spot.