The Dunbar number is a theoretical concept that defines a cognitive limit on the number of stable social relationships a human can maintain. Proposed by British anthropologist Robin Dunbar, the number is typically around 150. It represents the approximate number of people with whom an individual can sustain meaningful, ongoing relationships, including friends, family, and colleagues. Beyond this limit, maintaining close social ties becomes increasingly difficult, as the brain has a finite capacity for processing complex social connections.

Dunbar’s research began with studies of primates, where he observed a correlation between brain size—particularly the neocortex—and the size of social groups each species could sustain. Applying this to humans and the size of their brains, he concluded that the average person could maintain roughly 150 stable relationships. Observations of hunter-gatherer tribes and other early human societies reinforced this number, showing that groups naturally tended to form around this size. While this provides a useful reference for understanding individual social capacity, it is important to recognize that the Dunbar number is not a prescriptive tool for setting the size of communities. It is a theoretical limit on an individual’s capacity to maintain relationships, not a guideline for villages, organizations, or cities.

It is also important to note that the Dunbar number does not take into account the intelligence, social skills, or brain size of the individuals involved. It is reasonable to assume that more cognitively capable individuals may be able to maintain a greater number of meaningful relationships, while others may manage fewer. Intelligence, social acumen, and emotional skill can all influence the ability to handle complex social networks, so the number should be seen as a baseline, not an absolute limit.

In a community of 150 individuals, each person essentially serves as the center of their own Dunbar group, meaning that 150 distinct sets of relationships are represented within the community. No single member is likely to know all 150 people well; each individual maintains meaningful connections only with a subset of the group. Consequently, the Dunbar number provides little guidance for determining the “right” size of a community or a city. Instead, urban planners and community organizers use the principle to stimulate the creation of subgroups within larger populations. For example, parks, community centers, and walkable commercial districts are designed to stimulate and encourage smaller, manageable clusters of social interaction that acknowledge the Dunbar limit, encouraging meaningful connections without limiting the overall size of the city or community.

In modern contexts, the Dunbar number is evident in how people form smaller communities within larger ones. An unorganized community of LA Dodgers fans illustrates this well: within a city-wide fan base far exceeding 150 people, individuals form smaller groups of three or four to watch regular games, a slightly larger group of 12–20 for special events, and even larger gatherings at local bars. These nested subgroups reflect the same dynamics as a village model, where the overall community supports multiple smaller groups, each allowing for deeper connections and more active social participation.

This layered approach aligns perfectly with the Pasadena Village model, where the larger community is composed of numerous smaller groups. Members can participate in multiple clusters—social, recreational, or interest-based—without exceeding their individual cognitive limits. The village itself acts as a network of overlapping subcommunities, fostering trust, cohesion, and meaningful interaction. Far from limiting social possibilities, this model maximizes opportunities for connection while accommodating the brain’s natural constraints.

Research also shows that smaller groups are easier to manage than larger ones. However, this does not imply that large communities cannot function effectively; it simply means that larger groups require more structured management and intentional coordination. By focusing on subgroups and creating spaces where interactions naturally occur, communities can maintain the quality of relationships even as the population grows.

In summary, the Dunbar number highlights the limits of individual cognitive capacity for stable relationships. It does not prescribe community size, nor does it limit the potential of cities, organizations, or villages. Intelligence, social skill, and emotional ability all influence how many meaningful connections a person can handle, so the number should be understood as a baseline, not an absolute. Recognizing these factors allows communities—whether villages, organizations, or urban networks—to support richer, more meaningful relationships through smaller, overlapping subgroups, without being constrained by arbitrary numerical limits.

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