INTERVIEW: The Social Brain with Robin Dunbar
Issue 70: We interview Robin Dunbar about his new book on the psychology of successful groups
This week, we share a short interview with Robin Dunbar, an anthropologist and evolutionary psychologist at the University of Oxford who started his career studying the social relationships of wild monkeys and antelope in Africa. He is perhaps most famous for his concept of the Social Brain hypothesis or "Dunbar's number," which suggests that humans have a cognitive limit to the number of social relationships we can maintain at once.
He observed a correlation between the brain size of different primates and the size of the groups in which they live. By taking the average human brain size and extrapolating from the results of other primates, he proposed that humans can comfortably maintain about 150 stable relationships. He has explained it as "the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar.
Jay met Robin almost exactly a decade ago—on April 22, 2013—at a Social Neuroscience meeting in Paris. It wasn’t a bar exactly, but there were cocktails, a boat ride, and a conference loaded with fascinating talks on the social brain. So we were naturally thrilled when we saw that Robin now has a new book bringing these ideas to a mainstream audience.
His new book, The Social Brain: The Psychology of Successful Groups, co-authored with Drs. Tracey Camilleri and Samantha Rockey, faculty at Saïd Business School at the University of Oxford, combines insights about successful team dynamics from the worlds of evolutionary psychology and business management. They use research to explain the importance of group size, how to shape groups based on the task at hand, and offer readers a new perspective on the importance of social connection.
By explaining how the social brain works, they explain how human groups function and how to create high-performing teams. In many ways, this book is a great complement to The Power of Us because is drills into the dynamics of groups and organizations. Here is our interview with Robin:
What does your book teach us about group dynamics?
Three things.
That an organisation is a village, and the more we treat it as such the better it works.
The second is that there are distinct limits to the size of group that will work effectively. Certain numbers work well (5, 15, 50, 150, 500) but anything in between is much less efficient.
The third is that it doesn’t happen by magic: you have to invest time in getting to know the people in your group. Relationships matter, and they are expensive in terms of time to create—and then maintain.
What was the most surprising thing you learned as you were writing the book?
How often these ideas have actually been applied in practice by instinct or trial-and-error, and in many different everyday contexts; yet how little understood they actually are.
As co-author Sam Rockey has written:
“For example, in our time-strapped working days we may need to go small to move at speed (especially in moments of crisis) and also for quick, tactical decision making — but teams need to be bigger for creativity, strategy and thinking expansively. Different sized teams also need different types of leadership and processes.”
What is the biggest unanswered question on this topic going forward?
We understand how to engineer things on the small-to-medium scale. What has yet to be worked out is how exactly you scale all this up for very large organisations like multinationals.
Do you have any practical advice for people who want to apply these ideas?
Read our book....and think very carefully about it. There is no one-size-fits-all solution here. You need to understand the nature of your particular organisation and its purpose, and then apply the principles we outline.
This is just a teaser. We encourage you to buy a copy of the book to learn more!


News and Updates
We were delighted to receive copies of The Power of Us, now published in Romania and Japan! We love to hear from readers around the world, so if you get your hands on a copy, let us know what you think.
Our book as also featured in Forbes Japan this month, where Jay did an interview with Japanese Philosopher Tami_Yanagisawa about the implications for social identity for organizations and Japanese society.


Learn more about THE POWER OF US
If you like our newsletter, we encourage you to check out our award-winning book “The Power of Us: Harnessing Our Shared Identities to Improve Performance, Increase Cooperation, and Promote Social Harmony”. You can learn more about the book or order it from the links on our website (here). We keep the newsletter free, but are extremely grateful if you have a chance to purchase the book or buy it for a friend who wants to learn more about group psychology.
Catch up on the last one…
Last week’s newsletter was a behind-the-scenes look into the tea 🍵 behind Jay and his PhD student Claire Robertson’s research paper about the power of clickbait headlines. Read about it here!