What do you think?
Rate this book
The Social Brain: The Psychology of Successful Groups
How many people does the ideal team contain? How do groups bond, earn trust and forge shared identities? How can leaders build environments adaptable enough to respond to shocks and still enable people to thrive together? How can you feel close to people if your only point of contact is a phone or a computer? In The Social Brain leading experts from the worlds of evolutionary psychology and business management come together to offer a primer on great team working. They explain what size groups work and how to shape them according to the nature of the task at hand. They offer practical hints on how to diffuse tensions and encourage cooperation. And they demonstrate the vital importance of balancing unity and the need for different views and outlooks. By explaining precisely how the 'social brain' works, they show how human groups function and how to create great, high-performing teams.
272 pages, Hardcover
Published February 23, 2023
43 people are currently reading
590 people want to read
Ratings & Reviews
Friends & Following
Create a free account to discover what your friends think of this book!
Community Reviews
Displaying 1 - 17 of 17 reviews
June 25, 2025
When was the last time you felt truly connected at work? (ah never until my art jobs??)
notes:
- How many meaningful relationships can one person maintain? This seemingly simple question has profound implications for how we organize everything from businesses to communities. The answer, it turns out, is surprisingly consistent: about 150 people mark the natural limit of our social world.
- Neuroimaging studies reveal that regions like the frontal lobes, temporal lobes, and limbic system – the emotional center of the brain – determine how many social bonds we can maintain. And their capacity is finite.
- Small teams of five or fewer members create an environment of intimacy and trust that enables seamless communication and coordination. A study of software development teams revealed that groups of 3-5 members achieved 72% higher productivity than teams of 9 or more, with less communication overhead and decision-making complexity than with larger groups. In the military, special forces units specifically limit team sizes to 4-5 members to ensure the highest levels of trust and efficiency.
- When groups exceed their natural size limits, productivity and morale suffer. The solution isn't always staying small, but may instead mean organizing in networks of small units. The key is to find ways to preserve intimate working relationships while accommodating necessary growth
- These powerful effects stem from what biologists call the "kinship premium" - our innate tendency to help and value those closest to us family members above all others. The human brain processes close relationships through similar neural pathways as family relationships. In workplace settings, this closeness translates into measurable performance gains: Gallup's thirty-year research reveals that 63% of employees who report having a best friend at work demonstrate high engagement, compared to just 23% of those without close workplace bonds.
- These "Seven Pillars of Friendship" are shared dialect, geographical origin, career experiences, hobbies, worldview, sense of humor, and musical tastes. They predict relationship strength with surprising accuracy. When two people share six or more pillars, they typically form close, lasting bonds. Yet innovation often springs from connecting those who share fewer commonalities. The art, then, lies in balancing these forces.
- When Oxford University researchers conducted a study of rowing crews, they discovered something remarkable about human connection. Athletes rowing in sync with others produced double the endorphins of those rowing alone, despite exerting identical physical effort. This remarkable finding pointed to a deeper truth: our brains are wired to respond powerfully to shared rhythm and coordinated movement.
- studies indicate that just 1% of people tell 25% of all lies. A few bad actors, therefore, can poison an entire organization.
- However, many organizations respond to trust breakdown by implementing rigid controls, assuming workers need constant supervision. This approach often backfires, however. The Harvard Business Review reports that employees at high-trust companies experience 74% less stress, 106% more energy, and 50% higher productivity compared to those at low-trust organizations.
notes:
- How many meaningful relationships can one person maintain? This seemingly simple question has profound implications for how we organize everything from businesses to communities. The answer, it turns out, is surprisingly consistent: about 150 people mark the natural limit of our social world.
- Neuroimaging studies reveal that regions like the frontal lobes, temporal lobes, and limbic system – the emotional center of the brain – determine how many social bonds we can maintain. And their capacity is finite.
- Small teams of five or fewer members create an environment of intimacy and trust that enables seamless communication and coordination. A study of software development teams revealed that groups of 3-5 members achieved 72% higher productivity than teams of 9 or more, with less communication overhead and decision-making complexity than with larger groups. In the military, special forces units specifically limit team sizes to 4-5 members to ensure the highest levels of trust and efficiency.
- When groups exceed their natural size limits, productivity and morale suffer. The solution isn't always staying small, but may instead mean organizing in networks of small units. The key is to find ways to preserve intimate working relationships while accommodating necessary growth
- These powerful effects stem from what biologists call the "kinship premium" - our innate tendency to help and value those closest to us family members above all others. The human brain processes close relationships through similar neural pathways as family relationships. In workplace settings, this closeness translates into measurable performance gains: Gallup's thirty-year research reveals that 63% of employees who report having a best friend at work demonstrate high engagement, compared to just 23% of those without close workplace bonds.
- These "Seven Pillars of Friendship" are shared dialect, geographical origin, career experiences, hobbies, worldview, sense of humor, and musical tastes. They predict relationship strength with surprising accuracy. When two people share six or more pillars, they typically form close, lasting bonds. Yet innovation often springs from connecting those who share fewer commonalities. The art, then, lies in balancing these forces.
- When Oxford University researchers conducted a study of rowing crews, they discovered something remarkable about human connection. Athletes rowing in sync with others produced double the endorphins of those rowing alone, despite exerting identical physical effort. This remarkable finding pointed to a deeper truth: our brains are wired to respond powerfully to shared rhythm and coordinated movement.
- studies indicate that just 1% of people tell 25% of all lies. A few bad actors, therefore, can poison an entire organization.
- However, many organizations respond to trust breakdown by implementing rigid controls, assuming workers need constant supervision. This approach often backfires, however. The Harvard Business Review reports that employees at high-trust companies experience 74% less stress, 106% more energy, and 50% higher productivity compared to those at low-trust organizations.
Read
June 25, 2025"The Social Brain: The Psychology of Successful Groups" by Tracey Camilleri, Samantha Rockey, and Robin Dunbar explores the hidden patterns behind human connection and how they shape successful teams, organizations, and communities. Drawing on insights from psychology, evolutionary anthropology, and neuroscience, the authors argue that our capacity for social connection is biologically limited but profoundly powerful. Whether in a business setting or a close-knit community, the ways we form bonds, build trust, and synchronize with others significantly impact both individual wellbeing and group performance. This book brings together scientific research and real-world examples to reveal the mechanisms that allow groups to thrive—or falter—based on the quality of their social relationships.
At the heart of the book lies the idea that humans are neurologically equipped to manage only a certain number of meaningful relationships. This number, approximately 150, is known as Dunbar’s number, based on the research of Robin Dunbar himself. This limit appears consistently across cultures and time periods, from prehistoric tribes to medieval villages to modern corporations. Even on social media platforms, people maintain genuine interactions with a similar number of individuals, suggesting a deep-rooted biological constraint. The brain areas responsible for processing social information, such as the frontal and temporal lobes and the limbic system, have limited capacity, which naturally caps the number of relationships we can sustain. Beyond this threshold, group cohesion weakens and coordination becomes more difficult.
This numerical limit is not arbitrary; it reflects an intricate social architecture. People organize their social world in concentric layers. Closest to the center are about five individuals we deeply rely on, followed by a slightly larger circle of around fifteen, often those whose loss would affect us emotionally. A group of fifty forms the wider network of regular interaction, and finally, the broader layer of 150 encompasses all meaningful social ties. These natural groupings serve practical purposes. For example, small work teams of fewer than five members often achieve more effective communication, greater trust, and higher productivity. Research into software development teams shows that smaller groups outperform larger ones by avoiding the communication delays and decision-making complexity that come with size. Similarly, elite military units operate in teams of four or five to maintain tight coordination and deep mutual trust.
Real-life communities also exhibit this pattern. Hutterite settlements, for instance, deliberately split into new communities once they exceed around 150 members. After surpassing this size, social friction increases, cooperation declines, and collective motivation weakens. By returning to optimal group sizes through splitting, they restore harmony and shared purpose. This practice has remained stable for generations and supports the argument that our social limitations are not just cultural but deeply ingrained in our biology. In modern workplaces, scaling organizations without accounting for this natural cap can lead to inefficiencies and morale problems. However, growth need not be avoided entirely. Instead, organizations can be structured as networks of small, interlinked teams that preserve the benefits of intimacy and personal connection while allowing for expansion.
The book emphasizes that the presence—or absence—of human connection dramatically affects mental health, motivation, and workplace performance. A comparison between railway workers and warehouse employees illustrates this point vividly. Though railway workers often face more difficult physical conditions, their shared shifts and opportunities for conversation foster stronger interpersonal bonds. In contrast, warehouse employees working in isolation, guided by impersonal digital instructions, tend to report worse mental health. This effect mirrors larger studies showing that the quality of close relationships strongly predicts health outcomes. In fact, having strong friendships increases survival rates following a heart attack more than most traditional health factors.
These findings align with what is known as the kinship premium: our instinctive bias toward helping and valuing those we feel close to. In professional settings, people who report having a close friend at work show markedly higher engagement and job satisfaction. Gallup’s long-term studies confirm that employees with strong social ties are more likely to contribute creatively, collaborate effectively, and stay with an organization. Microsoft’s research supports this idea as well, showing that workplace relationships fuel innovation and resilience, especially during disruptive events like the COVID-19 pandemic. Companies that nurtured social bonds before the pandemic adapted more successfully to remote work, drawing strength from existing trust networks.
Sometimes, the solution is as simple as designing for more human interaction. In one warehouse case study, management adjusted break times to allow coworkers to spend time together. As a result, employees began coordinating lunch breaks, which led to increased cross-department collaboration and even improved safety records. This outcome reinforces the idea that small design choices can make a big difference when they foster real human contact.
The book also introduces the concept of the Seven Pillars of Friendship: common language, geographic origin, professional background, hobbies, worldview, humor, and musical taste. These dimensions help explain how we form bonds, and research shows that people who share several of these pillars are more likely to develop strong, lasting relationships. Interestingly, teams that share a moderate number of pillars—three or four—tend to perform best. Too many shared traits can lead to homogeneity and groupthink, while too few can hinder understanding. Balanced teams with both common ground and diversity tend to collaborate well and generate creative solutions. Organizations can apply this knowledge intentionally, such as arranging informal gatherings that facilitate discovery of shared interests or designing office spaces that encourage chance encounters.
Another key theme in the book is the power of synchronized activity to deepen social bonds. When people engage in rhythmically aligned behaviors—such as rowing, dancing, or even walking together—their bodies release endorphins, which enhance feelings of trust and connection. This biological response has roots in our evolutionary history, where synchronized movement helped early humans build cohesion and cooperation. The same mechanism is used today in military training, where repeated drills and coordinated actions create unshakable trust among unit members. Theater directors also use synchronization exercises to help casts bond before performances, creating an emotional safety net that fosters risk-taking and creativity.
Workplaces can adopt similar practices. A tech startup that introduced daily communal lunches found that shared mealtimes helped establish a natural rhythm among employees, improving communication and collaboration. These practices don’t require elaborate team-building programs—just spaces and routines that bring people into alignment through shared experience.
Trust is another critical component of successful groups. In tight-knit communities like Amsterdam’s diamond district, transactions worth millions are based on simple verbal agreements, relying on long-standing social trust. However, trust is fragile and can unravel quickly if a few individuals exploit the system. Behavioral experiments reveal how even small breaches of trust can trigger widespread collapse of cooperation. Alarmingly, a tiny proportion of people are responsible for a disproportionate number of lies, which can contaminate an entire network. Yet attempts to solve this problem through excessive monitoring or rigid controls often backfire. Instead of improving accountability, they foster resentment and disengagement.
A more effective approach is to build systems that assume most people are trustworthy and offer them autonomy and responsibility. The Dutch healthcare provider Buurtzorg exemplifies this philosophy. Its nurses work in self-managing teams with minimal supervision but shared accountability. This model not only improves patient outcomes and reduces costs but also boosts job satisfaction. The system works because it trusts professionals to act in the best interests of their clients and each other, reinforcing a positive cycle of responsibility and collaboration.
Ultimately, "The Social Brain" makes a compelling case for rethinking how we build teams, lead organizations, and design workplaces. Human beings are social creatures with clear cognitive limits and emotional needs. Recognizing and respecting these limitations allows organizations to unlock higher levels of engagement, creativity, and resilience. The book’s message is both scientific and humanistic: when we build environments that reflect how people naturally connect, we create the conditions for groups to flourish. By valuing small teams, encouraging shared experiences, and trusting in the goodwill of most individuals, we can cultivate not only stronger organizations, but also healthier, more fulfilling lives.
At the heart of the book lies the idea that humans are neurologically equipped to manage only a certain number of meaningful relationships. This number, approximately 150, is known as Dunbar’s number, based on the research of Robin Dunbar himself. This limit appears consistently across cultures and time periods, from prehistoric tribes to medieval villages to modern corporations. Even on social media platforms, people maintain genuine interactions with a similar number of individuals, suggesting a deep-rooted biological constraint. The brain areas responsible for processing social information, such as the frontal and temporal lobes and the limbic system, have limited capacity, which naturally caps the number of relationships we can sustain. Beyond this threshold, group cohesion weakens and coordination becomes more difficult.
This numerical limit is not arbitrary; it reflects an intricate social architecture. People organize their social world in concentric layers. Closest to the center are about five individuals we deeply rely on, followed by a slightly larger circle of around fifteen, often those whose loss would affect us emotionally. A group of fifty forms the wider network of regular interaction, and finally, the broader layer of 150 encompasses all meaningful social ties. These natural groupings serve practical purposes. For example, small work teams of fewer than five members often achieve more effective communication, greater trust, and higher productivity. Research into software development teams shows that smaller groups outperform larger ones by avoiding the communication delays and decision-making complexity that come with size. Similarly, elite military units operate in teams of four or five to maintain tight coordination and deep mutual trust.
Real-life communities also exhibit this pattern. Hutterite settlements, for instance, deliberately split into new communities once they exceed around 150 members. After surpassing this size, social friction increases, cooperation declines, and collective motivation weakens. By returning to optimal group sizes through splitting, they restore harmony and shared purpose. This practice has remained stable for generations and supports the argument that our social limitations are not just cultural but deeply ingrained in our biology. In modern workplaces, scaling organizations without accounting for this natural cap can lead to inefficiencies and morale problems. However, growth need not be avoided entirely. Instead, organizations can be structured as networks of small, interlinked teams that preserve the benefits of intimacy and personal connection while allowing for expansion.
The book emphasizes that the presence—or absence—of human connection dramatically affects mental health, motivation, and workplace performance. A comparison between railway workers and warehouse employees illustrates this point vividly. Though railway workers often face more difficult physical conditions, their shared shifts and opportunities for conversation foster stronger interpersonal bonds. In contrast, warehouse employees working in isolation, guided by impersonal digital instructions, tend to report worse mental health. This effect mirrors larger studies showing that the quality of close relationships strongly predicts health outcomes. In fact, having strong friendships increases survival rates following a heart attack more than most traditional health factors.
These findings align with what is known as the kinship premium: our instinctive bias toward helping and valuing those we feel close to. In professional settings, people who report having a close friend at work show markedly higher engagement and job satisfaction. Gallup’s long-term studies confirm that employees with strong social ties are more likely to contribute creatively, collaborate effectively, and stay with an organization. Microsoft’s research supports this idea as well, showing that workplace relationships fuel innovation and resilience, especially during disruptive events like the COVID-19 pandemic. Companies that nurtured social bonds before the pandemic adapted more successfully to remote work, drawing strength from existing trust networks.
Sometimes, the solution is as simple as designing for more human interaction. In one warehouse case study, management adjusted break times to allow coworkers to spend time together. As a result, employees began coordinating lunch breaks, which led to increased cross-department collaboration and even improved safety records. This outcome reinforces the idea that small design choices can make a big difference when they foster real human contact.
The book also introduces the concept of the Seven Pillars of Friendship: common language, geographic origin, professional background, hobbies, worldview, humor, and musical taste. These dimensions help explain how we form bonds, and research shows that people who share several of these pillars are more likely to develop strong, lasting relationships. Interestingly, teams that share a moderate number of pillars—three or four—tend to perform best. Too many shared traits can lead to homogeneity and groupthink, while too few can hinder understanding. Balanced teams with both common ground and diversity tend to collaborate well and generate creative solutions. Organizations can apply this knowledge intentionally, such as arranging informal gatherings that facilitate discovery of shared interests or designing office spaces that encourage chance encounters.
Another key theme in the book is the power of synchronized activity to deepen social bonds. When people engage in rhythmically aligned behaviors—such as rowing, dancing, or even walking together—their bodies release endorphins, which enhance feelings of trust and connection. This biological response has roots in our evolutionary history, where synchronized movement helped early humans build cohesion and cooperation. The same mechanism is used today in military training, where repeated drills and coordinated actions create unshakable trust among unit members. Theater directors also use synchronization exercises to help casts bond before performances, creating an emotional safety net that fosters risk-taking and creativity.
Workplaces can adopt similar practices. A tech startup that introduced daily communal lunches found that shared mealtimes helped establish a natural rhythm among employees, improving communication and collaboration. These practices don’t require elaborate team-building programs—just spaces and routines that bring people into alignment through shared experience.
Trust is another critical component of successful groups. In tight-knit communities like Amsterdam’s diamond district, transactions worth millions are based on simple verbal agreements, relying on long-standing social trust. However, trust is fragile and can unravel quickly if a few individuals exploit the system. Behavioral experiments reveal how even small breaches of trust can trigger widespread collapse of cooperation. Alarmingly, a tiny proportion of people are responsible for a disproportionate number of lies, which can contaminate an entire network. Yet attempts to solve this problem through excessive monitoring or rigid controls often backfire. Instead of improving accountability, they foster resentment and disengagement.
A more effective approach is to build systems that assume most people are trustworthy and offer them autonomy and responsibility. The Dutch healthcare provider Buurtzorg exemplifies this philosophy. Its nurses work in self-managing teams with minimal supervision but shared accountability. This model not only improves patient outcomes and reduces costs but also boosts job satisfaction. The system works because it trusts professionals to act in the best interests of their clients and each other, reinforcing a positive cycle of responsibility and collaboration.
Ultimately, "The Social Brain" makes a compelling case for rethinking how we build teams, lead organizations, and design workplaces. Human beings are social creatures with clear cognitive limits and emotional needs. Recognizing and respecting these limitations allows organizations to unlock higher levels of engagement, creativity, and resilience. The book’s message is both scientific and humanistic: when we build environments that reflect how people naturally connect, we create the conditions for groups to flourish. By valuing small teams, encouraging shared experiences, and trusting in the goodwill of most individuals, we can cultivate not only stronger organizations, but also healthier, more fulfilling lives.
December 27, 2024
If you enjoy math, this might be the book for you. However, I personally struggle with self-help books that rely heavily on rules, graphs, and charts. I think this is a common issue with many self-help books—they try to provide specific answers and advice, rather than offering guidance that helps readers find their own solutions.
July 26, 2023
Went in not expecting to like it much and indeed, some parts were either dull or obvious, often both. Nonetheless, it does a great job synthesizing various kinds of research on what makes for great groups - in life and work - and behaviors and patterns that can improve their social health (which as I learned from this book, will improve your personal health).
July 22, 2023
Interesting. I’ve studied this a lot so it wasn’t a lot super new but it was still relevant and interesting. I liked the first 2/3 or so best prior to too many management recommendations.
March 22, 2024
Hella eye opening and insightful!
July 1, 2024
3.5 rounded up. Started off well, but then clichéd gendered generalisation began to creep in by the penultimate chapter. No acknowledgement of neuro diversity or disability within groups/workplaces either, so all from a place of great privilege/elitism.
July 30, 2024
I thought this book would be highly readable when I saw the cover graphic - a procession of ants carrying a variety of leaves purposefully across the dust jacket: ants being the epitome of a successfully combined work and social ethic. And I was right: it is a breath of fresh air, a recovery of focus on the human dimensions of group working, an acknowledgment that we are social and emotional beings not entirely susceptible to quantitative analysis. When much in our world seems to be spiralling beyond manageable human scale, the authors consider how best we can nevertheless have a sense of belonging, purpose and flourishing, whether in our work or other context and what are the implications for leaders.
Their ideas have been road-tested in different situations across the world, drawing on the experience and research of other experts, and the result is a refreshing recovery of enlightened common sense at a time when sense seems all too uncommon.
Might the authors tackle the challenge of AI next...?
Their ideas have been road-tested in different situations across the world, drawing on the experience and research of other experts, and the result is a refreshing recovery of enlightened common sense at a time when sense seems all too uncommon.
Might the authors tackle the challenge of AI next...?
November 5, 2025
The Dunbar number is highly referenced when there's talk about social dynamics in the real world and building teams in companies. It mostly points to the notion that beyond around 150 people, it becomes harder to relate to each one sufficiently and ordinary communications aren't enough to keep the whole coherent. It was good to read a bit more about Dunbar's work, but this book is rich in anecdotes and short on specifics. It got redundant at times. That said, it's still an inspirational book for management with plenty of ideas to think about and do something about.
October 5, 2025
A well-researched overview of the social dynamics that affect groups working effectively together, primarily focused on a corporate perspective.
Unfortunately, I've come across most of the concepts, and while it's always useful to be reminded of them, I didn't learn anything particularly applicable. Hence, the modest 3 stars.
That being said, for those unfamiliar with the content, this is a good source of the types of factors which contribute to group cohesion and individual well-being.
Unfortunately, I've come across most of the concepts, and while it's always useful to be reminded of them, I didn't learn anything particularly applicable. Hence, the modest 3 stars.
That being said, for those unfamiliar with the content, this is a good source of the types of factors which contribute to group cohesion and individual well-being.
August 19, 2023
Covered a lot of old ground but once again it highlights the question for me...
If we know all this good stuff would make leadership better, why do so many people ignore it?
Hard to fathom.
If we know all this good stuff would make leadership better, why do so many people ignore it?
Hard to fathom.
October 17, 2023
Easy to understand for everyone. Inclusion is important. Lovely book with a positive vibe to it and simple but beautiful thoughts. Just enough information to deliver the message.
June 10, 2024
Exceptionally academic and dense, but also very high quality info. Worth the persistence and the several naps I fell into while reading this book
September 28, 2024
Really loved the book! It is so nice to read the theoretical underpinning of phenomena that are often very intuitive however not always considered in organizations.
October 21, 2024
About Dunbar's number
June 26, 2025
Very Good
Want to read
September 30, 2024Clever Apes in the Modern Workplace: Psychologist Robin Dunbar’s latest book argues companies are social groups that can’t be perfected like a machine— Max Beilby / Nautilus https://bit.ly/46DwM06
24_09_30 Very few holdings in U.S. Available for $10.49 on KINDLE
24_09_30 Very few holdings in U.S. Available for $10.49 on KINDLE
Displaying 1 - 17 of 17 reviews