Everything Everywhere Daily: History, Science, Geography & More - The Dunbar Number

Episode Date: January 14, 2021

There is a number, a very special number, which is inside all of us. It is inside you, inside me, and inside every person on Earth. It dictates our social interactions. It has determined the size of communities, Christmas Card lists, and has implications for social media. Learn more about the Dunbar Number on this episode of Everything Everywhere Daily. Learn more about your ad choices. Visit megaphone.fm/adchoices

There is a number, a very special number, which is inside all of us. It's inside you, inside me, and inside every person on earth. It dictates our social interactions. It has determined the size of communities, Christmas card lists, and has implications for social media. Learn more about the Dunbar number on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed.

It effectively turned day into night. And how it shaped the world now. Time travel with us every week on the Thuline podcast from NPR. This episode is sponsored by G Adventures. These are very troubled times. Even though things are starting to get better and more countries are opening up, people are still hesitant to travel, and that is totally understandable. That is why G. Adventures has announced its new Travel with Confidence Plus collection.

The Travel with Confidence Plus collection are 37 tours in 27 countries that have increased safety and sanitation protocols to protect you and other travelers. These tours will have smaller group sizes, private transportation, and cheaper options to get your own room, as well as more personal space. Gadventures has also earned the World Travel and Tourism Council's Safe Travel Stamp for their health and hygiene protocols and has implemented the Adventure Travel Trade Association's COVID-19 Health and Safety Guidelines. The Travel with Confidence tours are available for booking today, and we'll be departing from October 2, 2020 to the end of 2021. For more information and to book your tour, click on the link in the show notes. The Dunbar number is an idea created in the 1990s by University of Oxford anthropologist and psychologist Robin Dunbar.

He was doing research on the size of primate brains and the size of their social groups. One of the new theories at the time was known as the Social Brain Hypothesis. This postulates that the size of our brains developed in part to deal with complex social interactions. The larger our brains, the greater the group we can interact with. He found that the size of a primates' brain positively correlated to the size of the social group of the primates. With this data, he then extrapolated what the expected size of the social groups for humans should be, based on the average size of the human brain. The number he came up with was approximately 150.

Technically, the number he came up with was 148, but one hundred and one. is a nice round number and that is the number that is usually given. What the number reflects is sort of vague, but as Dunbar himself described it, it represents, quote, the number of people you would not feel embarrassed about joining uninvited for a drink if you happen to bump into them at a bar, unquote. Or, to put it more clinically, it is the cognitive limit to the number of people with whom one can maintain stable social relationships. What is interesting is that the number was determined before anyone checked to see if it was accurate. It was a prediction based on a model, or in scientific terms, a hypothesis. The Dunbar number is actually

a misnomer. Technically speaking, there are several Dunbar numbers. 150 is the number of people you might invite to a party. Below that is 50 people who you might consider friends, 15 who might be good friends, and five who would be intimate friends. Above the Dunbar number, there's a limit of about 1,500 people that you might be able to recognize. I should also add that all of this was set before humans develop social media. More on that in a bit. So when they started looking at human social groups, how well did the prediction pan out? The answer? Shockingly well. When they went back and looked at the archaeological data, they found that Neolithic communities tended to max out around 1 to 200 people. If they got any bigger, they would usually separate and form new

communities. Hunter-gatherer tribes, which had been studied by anthropologists around the world, tended to gravitate towards about 150 people. This has been shown true in Africa, America and the Amazon. The base unit of the Roman military was the century, and the size of a unit would usually be between 100 to 150 soldiers. The average size of a military unit known as a company is about 150 people. Hutterites and Amish communities tend to be about 150 people. Hutterites will actually seek to create a new community when they reach 150, and they have a hard limit of 200 people. A study of the list of names that people send Christmas cards to has an average of around 150.

Famously, the Gortex Corporation would open a new building once the number of employees became too large. Through trial and error, the number they landed on was 150 people in one building. They would only put in 150 parking spaces, and when it was full, they would open up a new building nearby. Time and time again, researchers have found that 150 is about the number of people we can have in our social circle at any given time. Now you might be wondering, what about social media? You can have a lot more than 150 friends on Facebook, for example.

Well, when researchers looked into it, they found that the actual number of people you interact with is pretty close to 150. While you can have up to 5,000 friends on Facebook, you can't really follow and pay attention to that many people. It's impossible. I did a quick check of my Facebook account, and I currently have 979 people listed as friends.

If I scan the list, I can recognize pretty much all of them. I get multiple friend requests daily from people who listen to this podcast or follow me on social media. However, I only tend to accept friend requests on Facebook if I've met someone in person. Most of the people I'm friends with I met in the past, and I haven't seen them in years or sometimes even decades. I haven't had a conversation with them, maybe since high school. They are in my outer circle, and at one time they may have been in my inner circle. There are some people I talk to every day. Some I might interact with a few times a month.

So yes, social media can help you keep track of things. people, but it doesn't really change the fact that you only have so much mental bandwidth and time. One UK study asked Facebook users how many friends they had. The average was about 200. When they asked how many of those people they could rely on for support, the average answer was about 15, which is the Dunbar number for your number of good friends. If you see someone on Twitter or Instagram that follows 10,000 people, it's just a game. You can't really follow that many people. It's impossible. Dunbar's number has been used to plan. office spaces and residential developments.

One of the failures of public housing developments in the 60s and 70s was that they were enormous and housed thousands of people. You can't really have a sense of community if you don't know most of the people who live with you. Likewise, the Swedish tax authority has conformed their offices to a 150-person limit. The Dunbar number hasn't met with universal support. There are some researchers who think the number is higher, closer to double the size. Others just disagree with the methodology.

Nonetheless, people do tend to gravitate towards their Dunbar numbers. So the next time you look at your Facebook friends list or send out invitations to a party, or even make a list to send out Christmas cards, think about the Dunmar number, and where the people you know would fit on it. Executive producer of Everything Everywhere Daily is James McAlla. The associate producer is Thor Thompson. Remember to leave a five-star review to get your review read on the show. They can be left at Apple Podcasts, Podcast, Republic, or wherever you listen to the show.

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