Robin Dunbar - Optimizing Human Connection (Dunbar's Number)

**Patrick O'Shaughnessy** (0:00)
This episode is brought to you by Tegus, the only research platform built for fundamental investors. How hard do you work to get the insights you need to make a great investment decision? How many hours do you spend digging through public records and expert transcripts or manually updating complex models? Investors should compete on their ability to analyze investments, not how well they aggregate data. That's why Tegus offers a unified end-to-end research platform that combines robust, qualitative content sets, up-to-date financial data, management and culture checks and more, all in the same easy to use, streamlined user experience. 95% of the top 20 global private equity firms use Tegus. Shouldn't you? Learn more and get your free trial at tegus.com/patrick.
You may have heard me reference the idea of maniacs on a mission and how much that idea excites me. Well, David Senra is my favorite maniac on one of my favorite missions with his weekly crafting of the Founders Podcast. Through studying the lives of legends, he weaves together insights across history to distill ideas that you can use in your work.
Founders reveals tried and true tactics, battle tested by the world's icons and has David's infectious energy to accompany them. With well over 300 episodes, your heroes are surely in the lineup and his recent episode on Oprah is particularly great. Founders is a movement that you don't want to miss. It's part of the Colossus Network and you can find your way to David's great podcast in the show notes.
Hello and welcome everyone. I'm Patrick O'Shaughnessy and this is Invest Like the Best. This show is an open-ended exploration of markets, ideas, stories and strategies that will help you better invest both your time and your money. Invest Like the Best is part of the Colossus family of podcasts and you can access all our podcasts including edited transcripts, show notes and other resources to keep learning at joincolossus.com.

**SPEAKER_2** (1:53)
Patrick O'Shaughnessy is the CEO of PositiveSum. All opinions expressed by Patrick and podcast guests are solely their own opinions and do not reflect the opinion of PositiveSum.
This podcast is for informational purposes only and should not be relied upon as a basis for investment decisions.
Clients of PositiveSum may maintain positions in the securities discussed in this podcast. To learn more, visit p-s-u-m dot v-c.

**Patrick O'Shaughnessy** (2:22)
My guest today is Robin Dunbar. Robin is a biological anthropologist, evolutionary psychologist and specialist in primate behavior. He is the man behind Dunbar's Number, a theory about the number of stable relationships we can maintain at once.
Robin unravels the thread of research that led him to Dunbar's Number and describes how this plays into every single person's layers of human connection. It was fascinating to hear how his findings on social circles have implications for optimally structured businesses and organizations, as well as the idea of homophily, all of which Robin thoughtfully explains. It was a treat to get to explore these topics with Robin Dunbar himself, so please enjoy this great conversation.
Well, Robin, thanks for doing this with me. I have to start with the obvious question, which is I would love to hear the story behind you arriving at the incredibly famous Dunbar's number.

**Robin Dunbar** (3:14)
Oh my goodness, how long have you got?

**Patrick O'Shaughnessy** (3:17)
I got a long time.

**Robin Dunbar** (3:18)
Quite a convoluted story really actually, because there was a proposal made back in the late 80s that reason primates, monkeys and eggs, had much bigger brains than anybody else was that they lived in complex societies and therefore needed a big computer to manage this, but it was based on largely casual observation as much as anything.
And that was a real problem, because primates do have much bigger brains. This stuff is expensive. Why would you be carting around all this heavy duty computer consuming energy like fury if you weren't doing anything different to what everybody else is doing? So anyway, this suggestion was based to do with the complexity of their social systems. And I had the bright idea one evening when I was trying to solve a completely different problem, which is why primates groom each other. So if that hypothesis is true, then we ought to find correlation between some measure of group size in primates and their brain size. And so I collected data on group sizes and I collected data on brain sizes.
I stuck them together and sure enough, there's a very nice relationship.
And now we're about three o'clock in the morning and getting quite excited about how this is going. It occurs to me that we should be able to use this to predict what humans group sizes are. So I did. This gave me a number about 150 So I then spent obviously the rest of the night and several other days and nights sitting in the library, looking for data, natural human group sizes.