Dunbar’s Number in agile

What is Dunbar’s Number and Why is it Relevant in Agile?

In the realm of team dynamics and organizational efficiency, the concept of Dunbar’s Number has sparked considerable interest. Named after British anthropologist Robin Dunbar, this theory posits that there is a cognitive limit to the number of stable social relationships an individual can maintain. While originally rooted in evolutionary biology, Dunbar’s Number has profound implications in today’s workplaces, especially within agile frameworks where collaboration, cohesion, and adaptability are paramount.

Agile teams thrive on close-knit collaboration, transparency, and constant communication—values that can be challenging to maintain as teams scale. The Agile Manifesto itself emphasizes “individuals and interactions over processes and tools,” highlighting the importance of human relationships in driving success. As teams grow, however, maintaining this level of interpersonal connection and cohesion becomes increasingly difficult. Dunbar’s Number suggests that there is a natural limit to how many people can effectively collaborate in a single group before communication and connection start to degrade.

In this article, we’ll explore how Dunbar’s Number applies to agile environments, providing a lens through which agile leaders and teams can optimize team size, structure, and interactions. From understanding the theory’s origins to its practical implications for agile frameworks like Scrum and SAFe (Scaled Agile Framework), this guide aims to equip agile practitioners with the knowledge to build teams that are not only productive but also highly cohesive.

Why Dunbar’s Number Matters in Agile Teams

Agile methodologies prioritize small, cross-functional, self-organizing teams that can move quickly, adapt to change, and deliver value continuously. For agile teams to achieve high performance, they need a strong foundation of trust, communication, and shared understanding. However, as teams grow larger, maintaining these qualities becomes more challenging. Communication lines multiply, and the risk of misunderstandings and delays increases. Dunbar’s Number offers insights into why teams beyond a certain size face these issues and how agile practitioners can address them.

Research suggests that Dunbar’s Number is not a fixed figure but rather a series of “layers” or group sizes that correspond to different levels of closeness and social interaction. These layers typically include groups of around 5, 15, 50, and finally 150 people—the maximum number most individuals can maintain meaningful connections with. Agile teams can use these layers to structure their organization, keeping core working groups small while leveraging larger group sizes for less frequent interactions.

Scientific Background: Understanding Dunbar’s Number

To truly grasp the significance of Dunbar’s Number in agile contexts, it’s essential to understand its scientific foundation. Dunbar’s Number is named after Robin Dunbar, a British anthropologist and evolutionary psychologist who first introduced this concept in the 1990s. Dunbar’s research was originally focused on primates, exploring the correlation between brain size and group size. His studies revealed that species with larger brains tend to live in larger social groups, likely because they possess the cognitive capacity to maintain more complex social relationships.

Dunbar then extended his research to humans, theorizing that the human brain can handle a maximum of approximately 150 stable social relationships. Beyond this threshold, the quality of relationships and the ability to maintain meaningful social connections start to decline. This limit became known as “Dunbar’s Number,” representing the approximate cognitive boundary of our social capacity.

The Layers of Dunbar’s Number

Dunbar’s Number is not a rigid figure but rather a hierarchy of relationships that exist in layers. Each layer reflects a decreasing degree of emotional closeness as the group size increases. Dunbar identified several key group sizes:

Intimate Layer (5 people): This layer represents our closest, most intimate relationships, typically family members or best friends. These are the individuals with whom we maintain the deepest level of trust and emotional connection.
Close Friend Layer (15 people): This second layer includes close friends or extended family members. People in this group receive a significant portion of our time and emotional investment, although less than those in the innermost layer.
Affinitive Group (50 people): This layer includes people we know well and interact with relatively often, such as regular colleagues, extended family, and social friends.
Casual Relationship Layer (150 people): This is the outermost layer that Dunbar identified as the upper limit for meaningful relationships. Beyond this, individuals become acquaintances rather than true social connections.

These layers reflect the amount of cognitive “effort” needed to maintain relationships. As each layer expands, the intensity and depth of connection decrease, which allows individuals to maintain a larger number of connections in the outer layers with less emotional investment. This concept has broad implications for team dynamics, particularly in agile contexts where team cohesion and collaboration are critical.

Studies and Evidence Supporting Dunbar’s Number

Dunbar’s Number is supported by various studies across different disciplines, from anthropology to organizational psychology. Here are some key findings that validate this theory:

Historical Examples: Dunbar examined historical communities, such as Neolithic villages and military units, and found that they often maintained group sizes close to 150. This number appears repeatedly in human history, suggesting that it may be a natural social limit hardwired into our brains.
Corporate Structures: Modern organizations often find that departments, divisions, or offices function best when kept around 150 people. Companies like Gore-Tex have famously used Dunbar’s Number as a guiding principle, ensuring that no division exceeds 150 employees. Once a division grows beyond that size, it’s split into smaller groups to preserve communication and cohesion.
Social Media Connections: Even in the era of social media, studies show that people struggle to maintain more than 150 meaningful connections. While social media platforms may encourage thousands of “friends” or “followers,” the depth of these connections tends to remain shallow. Dunbar’s Number remains relevant, even in a digital world where connecting with others is easier than ever.

Cognitive Limits and Social Bonding

Dunbar’s Number stems from the concept that our brain size, specifically the neocortex, limits our capacity for social bonding. The neocortex, responsible for complex reasoning and decision-making, determines our ability to process and maintain multiple social connections. Dunbar’s research posits that our cognitive resources, such as time and attention, are finite. As we spread these resources across more relationships, the depth and quality of each relationship inevitably decrease.

The implications of this theory are significant for agile teams. In small, close-knit teams, communication and trust develop naturally, leading to stronger cohesion and improved collaboration. However, as teams grow beyond a certain size, maintaining these social bonds becomes challenging. Members may struggle to keep track of each other’s roles, skills, and contributions, leading to reduced trust, communication gaps, and potential conflicts.

How Dunbar’s Number Relates to Agile Practices

In agile frameworks, Dunbar’s Number offers a scientific basis for recommendations on team size and organizational structure. For instance, Scrum advocates for small teams (typically between 5 and 9 members) to maximize collaboration and adaptability. This aligns with Dunbar’s inner layers, where cognitive load remains low, and relationships can be more meaningful. As team size increases, communication becomes more complex, and agile practices may lose effectiveness.

Scaled Agile Frameworks (SAFe), which organize teams into larger structures, use the principles behind Dunbar’s Number to design Agile Release Trains (ARTs) with optimal group sizes. By limiting an ART to roughly 50–125 people, SAFe aims to preserve a sense of community and connection that would be harder to maintain in larger groups. Dunbar’s insights into the human capacity for relationships help inform agile practices by encouraging agile leaders to prioritize manageable team sizes that enable strong, effective relationships.

The Human Cognitive Structure and Group Size

Dunbar’s Number is rooted in the concept that the human brain has a cognitive capacity for managing a limited number of social connections. This capacity affects our ability to sustain strong relationships, communicate effectively, and maintain a sense of trust and cohesion within groups. Understanding the relationship between brain structure and social dynamics provides valuable insights into the optimal size of agile teams, where collaboration and communication are paramount.

Cognitive Limitations and Relationship Depth

Dunbar’s research highlights that human cognitive resources, such as time, attention, and emotional investment, are finite. Maintaining close connections with others requires effort, which increases with the number of relationships we try to manage. Dunbar illustrated that humans naturally categorize their social circles into distinct layers, with each layer representing a decreasing level of emotional closeness as the group size grows:

Core Layer (5 people): These are the individuals with whom we maintain our closest and most intimate connections. This group often includes our best friends or closest family members and demands the highest level of emotional investment.
Sympathy Group (15 people): This layer expands to include close friends or family members who may not be as close as the core layer but still share a strong bond with us.
Affinitive Group (50 people): This group includes people we know well and interact with regularly, such as close colleagues, extended family, or social acquaintances.
Stable Social Group (150 people): This outer layer represents the maximum number of individuals with whom we can maintain meaningful, albeit less intimate, relationships. Beyond this, connections become more superficial, making it difficult to foster trust and cohesion.

This layering effect results from the limitations of the human neocortex, the part of the brain responsible for complex thought, social behavior, and decision-making. As social connections increase, the cognitive load on the neocortex rises, causing a decrease in the depth and quality of individual relationships. This phenomenon has practical implications for agile teams, where meaningful connections are essential to creating trust and facilitating open communication.

Communication Complexity and Group Dynamics

As group size increases, so does the complexity of communication. In small groups, communication tends to be direct, and information flows quickly among members. However, when the group size grows beyond a certain point, communication becomes more challenging. Members may need to rely on more formalized structures or intermediaries to relay information, increasing the likelihood of misunderstandings, delays, and information gaps.

This communication complexity can be illustrated by Metcalfe’s Law, which states that the number of possible connections in a network increases exponentially as more individuals join. In a group of 5, there are 10 potential connections, but in a group of 10, the number of connections jumps to 45. By the time a group reaches Dunbar’s 150-person threshold, the potential number of connections becomes overwhelming. In agile contexts, where fast-paced and frequent communication is crucial, this complexity can hinder a team’s ability to adapt quickly and make effective decisions.

For agile teams, this underscores the importance of maintaining smaller groups. Smaller teams can communicate more easily, develop deeper relationships, and build trust, which enhances cohesion and productivity. Agile frameworks such as Scrum capitalize on this by advocating for teams of 5 to 9 people, allowing them to function with minimal communication barriers and maintain close working relationships.

Social Bonding and Trust in Agile Teams

Trust is foundational for agile teams to operate effectively. Without trust, team members may hesitate to share their ideas openly, voice concerns, or collaborate freely. Dunbar’s Number highlights that our capacity to build and maintain trust is strongest within smaller groups, as we can invest more time and emotional energy into nurturing those relationships. In a large group, by contrast, maintaining trust and a strong sense of accountability becomes more challenging, as relationships lack the same level of depth.

In agile environments, trust directly impacts the effectiveness of practices such as daily stand-ups, sprint planning, and retrospectives. When trust is high, team members feel safe to be vulnerable, share challenges, and work together on solutions. When teams grow beyond the cognitive limits proposed by Dunbar, the risk of fragmentation increases, potentially leading to cliques, miscommunication, and a drop in team morale. By keeping teams within manageable sizes, agile leaders help foster an environment where trust can flourish.

The Role of Sub-Groups and Agile Release Trains in SAFe

In larger agile implementations, such as the Scaled Agile Framework (SAFe), Dunbar’s Number is used to inform the design of Agile Release Trains (ARTs). Each ART typically consists of 50 to 125 people, broken down into smaller Scrum teams that work together toward shared objectives. This structure respects Dunbar’s threshold for meaningful connections while allowing for scalability in large organizations.

The ART structure aligns with Dunbar’s layers by creating a larger community of individuals who share a common purpose without exceeding the cognitive limits for relationship management. Within each ART, teams can maintain strong relationships and trust, and the ART itself can foster a sense of collective identity without overwhelming individuals with excessive social connections.

Examples of Dunbar’s Number in Agile Teams

The benefits of applying Dunbar’s Number to agile teams can be seen in companies that prioritize small, autonomous teams. For example:

Amazon’s “Two-Pizza Teams”: Amazon famously keeps teams small enough that they can be fed with two pizzas. This principle aligns closely with Dunbar’s findings, as smaller teams can operate with minimal communication overhead, maintain close relationships, and make decisions faster.
W.L. Gore & Associates: The company behind Gore-Tex applies Dunbar’s Number to keep divisions within the 150-person limit. Each division functions autonomously, allowing them to preserve a close-knit culture and effective communication, even as the company grows.

These examples demonstrate that organizations can apply Dunbar’s principles to create scalable, efficient, and resilient structures that maintain the benefits of small-group dynamics while enabling growth and flexibility.

Applying Dunbar’s Number to Agile Teams

The principles behind Dunbar’s Number offer valuable insights for structuring agile teams to foster strong relationships, efficient communication, and sustained performance. In agile environments, where rapid feedback and collaboration are essential, maintaining the right team size can make all the difference in achieving agility, cohesion, and productivity. By understanding and applying Dunbar’s insights, agile leaders can optimize team dynamics to ensure that both small and large agile implementations benefit from human-centered, science-backed strategies.

Building Cohesion in Small Agile Teams

Agile methodologies, such as Scrum, inherently support Dunbar’s insights by emphasizing small team sizes. Scrum recommends teams of 5 to 9 members for development work. This size aligns well with Dunbar’s theory, as it falls within the first two layers (the “core” and “sympathy” groups) where interpersonal connection and trust remain strong.

Why small team sizes work well in agile:

Enhanced Communication: Smaller teams have fewer communication channels, reducing complexity and speeding up decision-making. This is crucial for agile teams, where rapid response to change is a fundamental principle.
Trust and Accountability: Team members in small groups are more likely to develop close relationships, which fosters mutual trust and a sense of accountability. When trust is high, team members feel safe to experiment, voice their concerns, and work collaboratively toward shared goals.
Higher Morale and Motivation: Research shows that people are more motivated when they feel connected to their team. Smaller groups allow individuals to feel seen and valued, increasing overall morale and engagement.

For agile leaders, Dunbar’s Number serves as a reminder of the importance of managing team size to avoid overloading cognitive and relational capacity. By keeping teams within this optimal range, leaders can maximize the benefits of agile practices, such as daily stand-ups, sprint planning, and retrospectives, as they create spaces where every voice is heard and valued.

Creating Sub-Teams for Larger Agile Implementations

As organizations grow and agile practices scale up, agile leaders face the challenge of maintaining cohesion and effective communication across larger groups. This is where the concept of sub-teams comes in. By dividing larger groups into smaller, autonomous teams that align with Dunbar’s suggested layers, organizations can retain the benefits of small-group dynamics while allowing for scalability.

How sub-teams work in agile contexts:

Independent yet Aligned: Each sub-team operates independently with its own goals and responsibilities, but remains aligned with the overarching objectives of the larger group. This structure helps maintain agility at scale by enabling small teams to work autonomously while contributing to a common purpose.
Cross-Functional Collaboration: Sub-teams often consist of cross-functional members, ensuring that each team has the skills needed to complete tasks without heavy dependencies on other teams. This reduces bottlenecks and allows teams to make faster, more cohesive decisions.
Regular Sync Meetings: While sub-teams work independently, periodic alignment meetings (e.g., cross-team retrospectives or joint planning sessions) ensure that they stay connected to the larger organization’s mission and maintain consistency in practices.

Example in Action:
Spotify’s “squad” model is a well-known example of creating sub-teams within a larger agile organization. Each squad functions as an independent Scrum team, focusing on specific features or components, but remains connected to other squads through “chapters” and “guilds” for cross-functional knowledge sharing. This model leverages Dunbar’s Number by breaking down larger groups into smaller, cohesive teams, allowing Spotify to maintain both agility and unity across a global organization.

Using Agile Release Trains (ARTs) in SAFe with Dunbar’s Number

In the Scaled Agile Framework (SAFe), Dunbar’s Number is applied to the design of Agile Release Trains (ARTs). Each ART typically includes 50 to 125 people, aligning with the outer layers of Dunbar’s structure, where meaningful connections can still be maintained without overwhelming cognitive capacity.

Why ARTs align with Dunbar’s insights:

Managing Cognitive Load: By limiting ARTs to 50-125 people, SAFe respects the cognitive limits on social connections, reducing the potential for communication breakdown and role ambiguity.
Building a Sense of Community: ARTs foster a sense of collective identity and belonging among members, helping large agile organizations feel less bureaucratic and more like cohesive communities working toward shared goals.
Facilitating Cross-Functional Collaboration: ARTs are organized around shared objectives and cross-functional collaboration, bringing together multiple Scrum teams that can communicate and coordinate effectively within the same train.

In SAFe, ARTs work within the framework of Dunbar’s Number by maintaining a size that supports human connection while allowing agile practices to scale. During the PI (Program Increment) Planning sessions, all ART members gather to align on goals, prioritize tasks, and identify dependencies. This event reinforces the sense of community and connection that Dunbar’s Number suggests is essential for effective collaboration in larger groups.

Practical Tips for Agile Leaders to Implement Dunbar’s Number

Applying Dunbar’s Number in agile environments involves thoughtful planning and a commitment to maintaining strong, manageable connections within teams. Here are practical strategies for agile leaders looking to use Dunbar’s principles to improve team dynamics and cohesion:

Maintain Optimal Team Sizes: Keep Scrum teams within the 5–9 range, ensuring they have the autonomy to make decisions and move quickly. If a team grows beyond this size, consider splitting it into two smaller teams with clearly defined objectives.
Use Sub-Teams to Scale: For larger projects, divide teams into smaller sub-teams or squads. Each sub-team should be self-sufficient, with the skills required to achieve its objectives, reducing dependencies on other groups.
Foster Strong Cross-Team Communication: Create rituals and ceremonies that allow for cross-team interaction without overwhelming members. For example, establish regular sync meetings or cross-team retrospectives that allow different sub-teams to share insights and coordinate.
Encourage a Strong Sense of Purpose and Shared Identity: In larger groups, maintaining cohesion can be challenging. Reinforce the group’s purpose regularly and celebrate achievements to build a shared sense of identity and pride within teams.
Leverage Technology Mindfully: In distributed or hybrid teams, communication tools like Slack, Microsoft Teams, and Trello can help maintain connections. However, avoid overloading team members with too many channels, as this can create cognitive fatigue. Choose a few key platforms that all members use consistently to streamline communication.
Monitor Team Health and Cohesion: Regularly assess team dynamics through feedback sessions, surveys, or retrospectives. Look for signs of fragmentation, communication gaps, or disengagement, which may indicate that the group has outgrown its ideal size or requires more structured support.
Promote Psychological Safety: Foster an environment where team members feel comfortable expressing concerns, asking questions, and taking risks. Psychological safety is crucial for creating trust, particularly in agile teams where experimentation and rapid iteration are the norm.

Real-World Examples of Dunbar’s Number in Agile Organizations

Numerous organizations apply Dunbar’s Number principles to enhance collaboration and maintain cohesion. Here are two examples:

Amazon’s “Two-Pizza Rule”: Amazon keeps its teams small enough that they can be fed with just two pizzas. This principle echoes Dunbar’s insights by limiting team size to maintain close relationships and effective communication.
Gore-Tex’s 150-Person Limit: W.L. Gore & Associates, the company behind Gore-Tex, organizes its teams to ensure no division exceeds 150 people. When a group reaches that size, it’s split into two new groups. This practice maintains cohesion and prevents bureaucracy from stifling innovation, creating a culture that aligns with Dunbar’s Number.

These examples underscore that applying Dunbar’s Number is not about strictly limiting team sizes but about fostering environments where individuals feel connected, valued, and engaged. When organizations prioritize manageable group sizes, they create spaces where agile principles can flourish, allowing teams to remain cohesive, agile, and resilient as they grow.

Why Dunbar’s Number is Relevant in Agile Teams

Dunbar’s Number holds significant relevance in agile environments, where effective teamwork, trust, and communication are essential for delivering value quickly and adapting to change. Agile frameworks like Scrum and SAFe (Scaled Agile Framework) emphasize collaboration, responsiveness, and continuous improvement, all of which require strong interpersonal bonds. By understanding and applying the principles behind Dunbar’s Number, agile leaders can optimize team dynamics and avoid common pitfalls associated with team size and complexity.

The Importance of Team Size in Agile

Agile methodologies favor small, cross-functional teams that can work autonomously and make quick decisions. Scrum, for example, typically recommends team sizes between 5 and 9 members. This range aligns closely with the inner layers of Dunbar’s model—small enough to maintain trust and frequent communication but large enough to bring in diverse skills and perspectives.

The reasoning behind this team size is grounded in the principle that smaller teams communicate more effectively and face fewer logistical hurdles in coordination. In larger teams, communication becomes more complex, and agile ceremonies like stand-ups, sprint planning, and retrospectives can lose their effectiveness as individuals struggle to stay engaged. Dunbar’s Number provides a framework that supports this agile guideline by highlighting the cognitive limitations that make managing larger teams challenging.

Enhanced Focus and Efficiency: In small agile teams, each member has a clearer understanding of their role and the team’s shared goals. This clarity reduces ambiguity and helps individuals focus on their responsibilities without excessive coordination efforts.
Stronger Sense of Ownership: When team sizes are kept small, individuals feel more accountable for their contributions. This sense of ownership fosters a commitment to quality and alignment with agile values like transparency, collaboration, and responsiveness.

Dunbar’s Number and Agile Release Trains (ARTs) in SAFe

In larger agile organizations that adopt frameworks like SAFe, Dunbar’s Number plays a role in structuring Agile Release Trains (ARTs). ARTs are collections of agile teams (usually between 5 to 12 teams) that work together on a shared product or value stream. Each ART typically consists of 50 to 125 people, aligning with Dunbar’s suggested cognitive limit for meaningful connections within groups.

SAFe’s approach respects Dunbar’s findings by ensuring that ARTs are large enough to achieve complex goals yet small enough to maintain a sense of community and effective communication. Within each ART, individual Scrum teams collaborate, but they’re still part of a larger group that meets regularly for ceremonies like PI (Program Increment) Planning. This setup allows SAFe to scale agile practices while minimizing the risk of fragmentation or siloed communication.

By applying Dunbar’s Number at this level, SAFe creates a balance: each ART functions as a self-contained unit with a shared vision, while each team within the ART operates autonomously on its own tasks. This structure helps large organizations reap the benefits of agile—speed, flexibility, and alignment—without overwhelming team members with excessive coordination and complex communication pathways.

Communication Complexity and Cognitive Load in Agile Teams

As teams grow beyond Dunbar’s cognitive limits, the complexity of communication can lead to challenges that directly impact agility. Agile teams rely on constant feedback, transparency, and collaboration to deliver iterative improvements. When teams exceed the optimal size, they face increased cognitive load, which can disrupt these essential agile practices.

For example, in a team of 10, each member has 45 potential communication channels with other team members. As the team size doubles, the number of possible communication channels increases exponentially. This leads to:

Slower Decision-Making: Larger groups require more time to align on decisions, which can slow down the iterative process central to agile.
Higher Risk of Miscommunication: With more people involved, there’s a greater likelihood of information loss, misunderstandings, or inconsistent messaging.
Reduced Engagement: As communication complexity increases, some team members may feel less connected, leading to disengagement and decreased morale.

By keeping team sizes within Dunbar’s suggested limits, agile organizations can avoid these issues, ensuring that teams remain agile, connected, and engaged. Agile leaders can use this principle as a guideline when deciding whether to add more people to a team or split larger teams into smaller, more focused groups.

The Role of Trust and Psychological Safety

Trust and psychological safety are foundational for agile teams, and Dunbar’s Number highlights the importance of maintaining relationships within manageable limits to foster these qualities. Psychological safety—the ability for team members to speak up, take risks, and make mistakes without fear of negative consequences—is a core requirement for agile practices like retrospectives, continuous feedback, and experimentation.

Dunbar’s research suggests that trust is strongest within smaller, close-knit groups. In agile teams that respect Dunbar’s cognitive limit, members are more likely to feel comfortable sharing ideas, voicing concerns, and collaborating openly. As team size increases, maintaining this level of trust becomes challenging, and psychological safety may erode.

Implications for Agile Practices:

Retrospectives: Smaller teams feel more comfortable discussing what went wrong and identifying areas for improvement. In larger groups, individuals may hesitate to speak openly, limiting the effectiveness of retrospectives.
Continuous Feedback: When team members trust each other, they are more likely to provide and accept constructive feedback. Smaller teams enable more direct and transparent feedback loops, a key component of agile improvement.
Experimentation: Agile encourages a culture of experimentation, where teams test ideas, learn from failures, and iterate. Psychological safety in small teams allows members to embrace this process without fear, fostering innovation.

Agile leaders who understand Dunbar’s Number can create environments where psychological safety thrives by keeping team sizes manageable. This ensures that agile values are not only upheld but also deeply embedded in the team’s culture.

Dunbar’s Number as a Guideline for Scaling Agile

When scaling agile across larger organizations, leaders can use Dunbar’s Number as a strategic guideline for structuring teams, ARTs, and even entire departments. This principle helps maintain human-centered agile values in large settings without sacrificing efficiency and productivity.

Using Dunbar’s Number to Scale Agile:

Limit Team Sizes: Keep Scrum teams within 5 to 9 members to ensure strong communication, trust, and a sense of ownership. If a team grows beyond this size, consider splitting it into two smaller teams that can work independently.
Form Agile Release Trains (ARTs): For larger organizations, create ARTs of 50 to 125 people to allow multiple agile teams to work toward a common goal. This structure keeps ARTs manageable and prevents the organization from losing cohesion.
Encourage Cross-Team Collaboration Without Overwhelming Connections: Ensure that teams within ARTs have regular opportunities to align, such as through PI Planning and sync meetings. However, avoid creating too many layers of interaction that could overload team members.
Foster Strong Leadership in Each Layer: Assign Scrum Masters, Product Owners, and Release Train Engineers to help maintain clarity and alignment within each layer of the agile organization, from teams to ARTs. These leaders help manage connections and ensure that communication flows smoothly.

Real-World Examples of Dunbar’s Number in Agile Contexts

Several organizations have successfully applied Dunbar’s Number to maintain agility at scale while fostering strong team dynamics:

W.L. Gore & Associates: Gore has famously structured its organization around Dunbar’s Number, ensuring that no division exceeds 150 people. When a division grows larger, it’s split to maintain close working relationships and avoid bureaucracy. This practice keeps teams agile, resilient, and able to maintain a strong sense of community.
Amazon’s “Two-Pizza Rule”: Amazon organizes teams to be small enough that two pizzas can feed everyone. This rule aligns with Dunbar’s insights, as small teams can make decisions quickly, work autonomously, and remain agile without the cognitive overload associated with larger groups.
Spotify’s Squad Model: Spotify’s agile framework breaks large product teams into “squads,” each small enough to retain a close-knit, collaborative culture. Squads work autonomously but are aligned through “tribes” and “chapters” for cross-team knowledge sharing, creating a scalable structure that respects Dunbar’s limit.

Practical Strategies for Applying Dunbar’s Number in Agile Organizations

While the theory of Dunbar’s Number offers valuable insights into the optimal size for effective group dynamics, its practical application requires careful planning and consideration. Agile organizations, particularly those that scale using frameworks like SAFe or Spotify’s model, can use Dunbar’s insights to design teams that balance human connection with productivity. In this section, we’ll cover actionable strategies for agile leaders looking to implement Dunbar’s principles in real-world settings, enhancing communication, trust, and efficiency across all team levels.

1. Keep Scrum Teams Small and Focused

The first step in applying Dunbar’s Number is to ensure that Scrum teams remain within the recommended 5–9 member range. This aligns with the inner circles of Dunbar’s model, where close relationships and effective communication are most feasible.

Tip: Regularly review team sizes and objectives. If a team grows beyond 9 members due to new requirements or scope expansion, consider splitting the team into two smaller, autonomous Scrum teams with distinct goals and responsibilities.
Benefit: Smaller teams maintain better communication, build stronger relationships, and foster a sense of shared accountability, all of which are crucial for agile performance.

Example in Action:
In a large tech company, a Scrum team handling both frontend and backend work began struggling with coordination as they grew to 12 members. By splitting into two specialized teams (one for frontend, one for backend), they reduced communication complexity and were able to align more effectively on their respective tasks, enhancing overall productivity.

2. Create Agile Release Trains (ARTs) to Scale Cohesion

For larger organizations following SAFe, structuring groups into Agile Release Trains (ARTs) of 50–125 people can preserve Dunbar’s optimal group size at scale. ARTs act as collections of Scrum teams that work together on a common product or project but still benefit from a manageable group size.

Tip: Design ARTs around logical value streams or product lines to maintain a clear focus and shared purpose. This alignment reduces dependency on external teams and enhances the team’s sense of community and belonging.
Benefit: ARTs allow organizations to scale agile practices while preserving the benefits of smaller, more cohesive groups. This structure reduces communication barriers, supports alignment, and maintains a sense of shared mission.

Example in Action:
A manufacturing company with multiple product lines structured its ARTs by product focus, keeping each ART within the 50–125 member range. This setup enabled the organization to maintain clear goals for each product line while allowing teams within each ART to operate autonomously and collaboratively.

3. Use Cross-Team Syncs and Alignment Meetings

While small teams operate well independently, agile organizations still need alignment across teams to avoid silos and maintain consistent objectives. Cross-team syncs, such as PI (Program Increment) Planning in SAFe, allow teams to coordinate efforts while respecting Dunbar’s cognitive limits.

Tip: Schedule regular cross-team syncs, such as bi-weekly alignment meetings or quarterly planning sessions, where all teams within an ART or department can align on goals, dependencies, and priorities. Use these sessions to reinforce shared goals and facilitate knowledge sharing.
Benefit: Alignment meetings keep teams on track without overwhelming them with constant cross-functional communication, balancing autonomy with coordination.

Example in Action:
Spotify holds regular “chapter meetings” across squads working on related areas, such as user experience or platform reliability. These meetings allow cross-functional experts to discuss best practices and share updates without disrupting the autonomy of individual squads.

4. Foster a Sense of Identity within Teams and ARTs

As team size grows, it becomes essential to reinforce a sense of identity and belonging to help members feel connected to their peers and committed to the organization’s mission. Dunbar’s research indicates that individuals perform better in groups where they share a sense of belonging and purpose.

Tip: Create rituals, symbols, or group traditions within teams or ARTs. For example, team mascots, unique team names, or regular team-building events can strengthen the group’s identity.
Benefit: A strong team identity increases engagement and motivation, as members feel they are part of something meaningful. This fosters resilience and cohesion, particularly in larger agile setups.

Example in Action:
A software company implemented a team-naming tradition where each Scrum team chooses a name and logo that represents their values and objectives. These symbols are displayed in shared online spaces, reinforcing team identity and giving members a greater sense of pride and camaraderie.

5. Support Psychological Safety Through Smaller Group Interactions

Psychological safety—the confidence that team members can speak up without fear of criticism—is crucial for agile teams to thrive. Smaller groups, as suggested by Dunbar, create environments where members feel more comfortable sharing ideas and giving feedback.

Tip: Encourage regular sub-team discussions, where small groups of 2-3 members meet to discuss specific tasks, challenges, or ideas. These smaller interactions can foster psychological safety and help teams address issues before they escalate.
Benefit: Smaller interactions within larger teams or ARTs build trust and help agile teams maintain open communication, supporting the experimentation and transparency that agile practices rely on.

Example in Action:
A consulting firm encouraged “buddy check-ins” where team members would meet one-on-one every two weeks. This setup fostered stronger personal connections and helped team members address concerns in a private, safe setting, ultimately improving the trust within the larger team.

6. Designate Agile Roles for Communication Flow

As teams and ARTs grow, communication complexity can increase, making it essential to structure communication channels carefully. Appointing specific agile roles like Scrum Masters, Product Owners, and Release Train Engineers can help streamline communication and ensure alignment without burdening all members with excessive information.

Tip: Ensure that each team has a designated Scrum Master or Agile Coach to facilitate communication and remove obstacles. For ARTs, appoint a Release Train Engineer to coordinate across teams and manage dependencies.
Benefit: Agile roles help maintain efficient communication and clear accountability within each team, preventing information overload and ensuring that every member stays informed without unnecessary distractions.

Example in Action:
In a multinational corporation, Release Train Engineers organized weekly syncs with Scrum Masters across teams to discuss dependencies and address any cross-team issues. This allowed individual team members to focus on their tasks while ensuring that necessary information flowed effectively between teams.

7. Leverage Technology to Enable Efficient Communication

For distributed or hybrid agile teams, communication technology is essential for maintaining connections within Dunbar’s limits. However, it’s important to be selective in tool usage to prevent cognitive overload.

Tip: Use a core set of communication tools and define clear usage guidelines. For instance, Slack or Microsoft Teams can be used for quick communication, while more detailed discussions are held on platforms like Confluence or Jira.
Benefit: Limiting tools reduces “communication fatigue” and makes it easier for team members to find and process relevant information, supporting more effective and focused collaboration.

Example in Action:
A remote-first company adopted Slack for daily communications and designated Confluence as the central knowledge repository. This setup streamlined workflows and ensured that team members weren’t overwhelmed by multiple channels, creating a consistent and efficient communication process.

8. Monitor Team Health and Adjust as Needed

Regularly assessing team health is essential for maintaining cohesion and effectiveness as teams evolve. By monitoring team dynamics and adjusting structures as necessary, agile leaders can ensure that teams stay within their optimal size and maintain strong relationships.

Tip: Use periodic team health surveys, feedback sessions, or retrospectives to assess morale, communication quality, and cohesion. Be attentive to signs of disengagement or communication breakdowns, which may indicate that the team size or structure needs adjustment.
Benefit: Regular assessments help agile leaders detect early signs of issues, allowing them to make timely adjustments, whether by rebalancing workload, adjusting team size, or implementing new communication practices.

Example in Action:
A financial services company conducted quarterly team health surveys to gather anonymous feedback. When a team reported feeling overwhelmed, the Product Owner worked with the team to adjust sprint goals, improving morale and restoring a sense of control within the team.

9. Encourage Knowledge Sharing Across Teams Without Overloading

While smaller teams benefit from focused collaboration, agile organizations must still facilitate knowledge sharing to prevent silos. Knowledge-sharing sessions across teams can ensure that best practices and insights are shared without overwhelming team members.

Tip: Schedule monthly or quarterly knowledge-sharing sessions where representatives from each team present key learnings or innovative approaches. Use documentation tools to create a centralized knowledge base that members can access as needed.
Benefit: Knowledge-sharing sessions ensure alignment and spread valuable insights across teams while respecting cognitive limits by not requiring constant cross-team interaction.

Example in Action:
In a healthcare tech firm, each team nominated a “knowledge ambassador” who attended monthly cross-team meetings and shared insights with their team afterward. This system kept team members informed of broader company developments without adding to their daily communication burden.

Case Studies and Testimonials: Applying Dunbar’s Number in Agile Organizations

To see Dunbar’s Number in action, let’s examine real-world case studies and testimonials from agile organizations that have effectively applied these principles to improve team cohesion, communication, and productivity. These examples highlight the benefits and practical challenges of adhering to Dunbar’s Number in agile contexts, offering valuable insights for leaders seeking to build scalable yet connected teams.

Case Study 1: Amazon’s “Two-Pizza Teams”

Background
Amazon, a global e-commerce and technology leader, is renowned for its focus on efficiency, autonomy, and innovation. To maintain agility as it grew into a large organization, Amazon implemented a unique team structure known as the Two-Pizza Rule. This rule dictates that teams should be small enough to be fed by two pizzas, aligning with Dunbar’s principle of maintaining manageable group sizes to promote productivity and effective communication.

Application of Dunbar’s Number
Amazon’s small team structure, typically consisting of 6–10 members per team, allows each team to maintain direct communication, close relationships, and a strong sense of ownership over their projects. Each team operates as a semi-autonomous unit, reducing dependency on other teams and minimizing communication barriers.

Outcomes
By maintaining small, independent teams, Amazon has achieved:

High levels of autonomy and accountability, with each team empowered to make decisions quickly.
Enhanced focus and efficiency, as small teams can align on goals more easily and reduce coordination overhead.
Continuous innovation, driven by a strong sense of ownership and motivation within each team.

Testimonial from an Amazon Team Lead
“Amazon’s Two-Pizza Rule has empowered our team to stay focused, collaborate closely, and deliver value quickly. In larger teams, decision-making would slow down, but in our small group, we can pivot fast and remain agile. I can’t imagine managing a team of 15 or 20 people with the same level of efficiency.”

This case study demonstrates how Amazon has applied Dunbar’s Number to sustain a culture of innovation and speed, showing that even large organizations can remain agile by creating smaller, autonomous teams.

Case Study 2: W.L. Gore & Associates – Limiting Division Size to 150

Background
W.L. Gore & Associates, the company behind the innovative Gore-Tex fabric, is known for its unique organizational culture and commitment to small, self-managed teams. Inspired by Dunbar’s Number, Gore follows a principle of limiting each division to 150 people. When a division exceeds this size, the company creates a new division, ensuring that each group remains cohesive and manageable.

Application of Dunbar’s Number
By capping each division at 150 people, Gore ensures that individuals can maintain meaningful relationships with their colleagues, fostering a strong sense of community and trust. Each division operates semi-independently, with leaders empowering team members to manage their responsibilities autonomously.

Outcomes
This structure has resulted in:

Strong team cohesion and a supportive work environment, where employees feel valued and connected to their peers.
Increased innovation, as employees are encouraged to take ownership of their work and experiment without excessive hierarchy.
Efficient decision-making within divisions, as smaller groups can reach consensus more easily.

Testimonial from a Gore Team Member
“Working in a division capped at 150 people makes it easy to know everyone’s name and feel like you’re part of a family. This environment makes me feel more engaged and willing to contribute ideas, knowing I’m part of a close-knit group with a shared mission.”

W.L. Gore’s approach showcases how Dunbar’s Number can foster a strong, cohesive culture that encourages collaboration, loyalty, and innovation, even as the company expands.

Case Study 3: Spotify’s Squad Model

Background
Spotify, the music streaming giant, has long been recognized for its innovative approach to agile at scale. As Spotify grew, it needed a scalable yet cohesive team structure to continue delivering high-quality user experiences. The company introduced the Squad Model, inspired by agile principles and Dunbar’s insights.

Application of Dunbar’s Number
Spotify organizes its workforce into small “squads,” with each squad consisting of 5–9 members. Squads operate as autonomous Scrum teams, focusing on specific features or areas of the Spotify platform. These squads are further grouped into “tribes” (50–150 people) to align on larger goals while preserving the benefits of small team sizes.

Outcomes
Spotify’s Squad Model has enabled:

Scalability with cohesion, as squads remain independent while benefiting from the alignment provided by larger tribes.
Enhanced communication within squads, allowing them to operate efficiently without being bogged down by cross-team dependencies.
High levels of engagement and motivation, as squad members feel connected to their small teams and empowered to make meaningful contributions.

Testimonial from a Spotify Squad Member
“Being part of a squad means I work closely with a few people on shared goals, so we’re always in sync and can make decisions quickly. The tribe gives us a broader network and a sense of unity, but day-to-day, we stay focused and cohesive within our squad.”

Spotify’s application of Dunbar’s Number in its Squad Model demonstrates that large-scale agile implementations can achieve scalability without sacrificing team connection and effectiveness.

Case Study 4: Salesforce’s Agile Transformation with ARTs

Background
Salesforce, a leader in cloud-based CRM solutions, has undergone an agile transformation to remain responsive to market needs. The company adopted the Scaled Agile Framework (SAFe), creating Agile Release Trains (ARTs) to organize teams around major initiatives.

Application of Dunbar’s Number
Each ART at Salesforce comprises 50–125 people, in alignment with Dunbar’s limit for stable relationships. By organizing teams into ARTs, Salesforce maintains a balance between scalability and interpersonal connection. ARTs bring together multiple cross-functional teams, allowing them to collaborate within a manageable structure.

Outcomes
With ARTs structured around Dunbar’s Number, Salesforce has seen:

Improved collaboration and knowledge sharing across teams within each ART, while reducing the risk of communication overload.
Greater adaptability to changing project demands, as each ART can pivot without complex coordination outside its group.
Enhanced alignment on goals, as ARTs meet regularly to plan and synchronize efforts, maintaining a unified direction.

Testimonial from a Salesforce Agile Coach
“ARTs have transformed how we work at Salesforce. Having 100 people working on related initiatives feels more organized and connected than trying to manage 200 people across different functions. It’s like a community where everyone understands the big picture but can still focus on their specific goals.”

Salesforce’s use of ARTs highlights the practical advantages of Dunbar’s Number for structuring agile organizations at scale, demonstrating how teams can stay connected and aligned even within large projects.

Key Takeaways from the Case Studies

These case studies illustrate several powerful lessons for agile leaders:

Small Teams Drive Autonomy and Accountability: Both Amazon and Spotify exemplify how small, autonomous teams promote faster decision-making, greater accountability, and higher engagement. Dunbar’s Number shows that limiting team size allows members to build strong, trusting relationships that enable agility.
Capping Larger Groups Enhances Cohesion: W.L. Gore and Salesforce demonstrate that even larger organizations can stay cohesive by adhering to Dunbar’s 150-person threshold. By capping divisions or ARTs, these companies prevent fragmentation, ensure clear communication, and foster a sense of community.
Clear Role Definitions Streamline Communication: All four companies emphasize structured communication channels and roles (e.g., Scrum Masters, Agile Coaches, and Release Train Engineers) to manage information flow effectively. This reduces cognitive load and helps team members focus on high-priority tasks.
Flexibility and Scalability are Possible with Dunbar’s Insights: These examples show that applying Dunbar’s Number is not about rigidly limiting team sizes but about creating manageable structures that foster close relationships. By combining small teams with scalable frameworks, companies like Spotify and Salesforce maintain agility even as they grow.

In conclusion, these case studies validate the effectiveness of Dunbar’s Number in agile environments. By structuring teams and divisions within cognitive limits, organizations can optimize communication, trust, and motivation, ultimately driving productivity and adaptability. Agile leaders who leverage Dunbar’s insights create environments where teams feel connected, engaged, and empowered to deliver their best work—even as their organizations expand.