Dunbar’s number is a proposed cognitive limit of approximately 150 people with whom an individual can maintain stable, meaningful social relationships—those involving trust and obligation. Proposed by anthropologist Robin Dunbar, this number suggests that, regardless of social media, our brain size limits our inner circle to about 150, typically spanning from intimate to casual friends.
Key Aspects of Dunbar’s Number
- The Limit (150): The core number representing “meaningful” relationships (e.g., people you would invite to a wedding).
- Origin: Based on the relationship between primate neocortex size and group size, extrapolated to humans in 1993.
- Nested Layers: Friendships often operate in layers (similar to waves on a pond):
- 5: Intimate friends (best friends).
- 15: Good friends (trusted friends).
- 50: Close friends.
- 150: Meaningful contacts.
- 500: Acquaintances.
- 1,500: People you can recognize.
Application and Criticism
- Applications: The 150-person limit has been applied to organizational management, such as military company sizes, the “two-pizza” rule at Amazon, and optimal Gore-Tex factory sizes.
- Criticism: Some researchers argue that advancements in technology allow for larger networks, or that the mathematical basis (extrapolation from primates) produces too wide a range of numbers, as seen in this PMC article and this Biology Letters study.
Despite criticism, the concept remains a popular framework for understanding social networking and cognitive constraints on relationships.
Know Thyself 