British anthropologist Robin Dunbar postulated in the 1990s that, given our brain size, human beings can only maintain 150 stable relationships.
A new study has taken a look at modern and traditional societies, and has concluded that the number is actually 132. But there is another limitation, and that is the small number of close links an individual can maintain. This account states that the maximum number of close links we can maintain is on average about five.
There are a few barriers to understanding what is being claimed. First, you have to be a Royal Fellow, or pay to read the whole article. Secondly, they don’t talk about Dunbar’s number, rather about Erdős–Rényi networks. You have to be a mathematician to understand those. Finally, the authors are engineers rather than social scientists, so we can’t make assumptions as to how they define terms.
I’ve used the term “close link” rather than just “link”, by which I think they mean the equivalent of a close friend, someone you know well. However, the groups are meant to be cohesive, which means that as a group member you need to know how everyone relates to everyone else, the expectations and obligations that bind them, and how you would expect them to act and react in various situations.
The Phys.org piece explains how it’s meant to work:
- Prior research has shown, the researchers note, that humans are only capable of maintaining a certain number of people in their social world, currently, the upper limit appears to be 132 people. But, not all of those people are directly connected to any one individual, it all happens through links. Harré and Prokopenko suggest the upper limit on the number of direct friends for most people is about five. The upper limits appear to be based on biology, they note—as the human brain developed, people were living together in small groups that lived as hunter-gatherers. That led to the development of links, which are direct connections between two people, generally two people that have some type of emotional attachment. To form a larger group, it isn’t necessary for every person in that group to form a connection with everyone else, all it takes is for a network of connections to exist.
In primitive terms, the researchers explain, that would mean that not all of the people in a small hunting party would necessarily have to be friends, instead, each would have to be friends with just one or two of the people in the group. They have calculated that to have a social circle of 132 people, each person would only have to have a link with just five people. They also have found that the number of links a person has can be related to group size, as the group grows, more links are needed to maintain cohesiveness. As it grows to 15, for example, there will exist on average 3 links per person; in groups of 45, the number of links would grow to 3 or 4.
The ABC summarises the relationship between “links” and group size thus:
How many links do you need to maintain a network?
- Group of five = one to two links
- Group of 15 = two to three links
- Group of 45 = three to four links
- Group of 132 = four to five links
If our capacity for close links is limited to about five, then we could not participate in more than a few cohesive groups. Any way that’s how I understand it.
The authors contrast such social networks with hierarchical networks, which have rules and leaders. Hierarchical networks can be much larger and the need to know anyone within the network is reduced. For example, it would be possible to sing in a choir without knowing anyone else.
Many groups in modern society are to a more or less degree hierarchical, I think.
Nearly two years ago we had a look at Dunbar’s number. The post and comments are worth rereading in the light of the new research.
I would agree with John D’s comment that modern societies are very different from traditional societies. We have more general rules, norms an laws. Individualism is I think a phenomenon that perhaps emerged with the Renaissance.
This comment from John pertains:
It is interesting to compare the Groote Eylandt Aboriginal and European communities. In the case of the Europeans we have general rules for dealing with each other so we don’t really need to know who someone is before we can deal with someone. (Gender, age etc. may count but they are still general rules.)
By contrast many of the Aboriginal rules are relationship driven. (For example, the rules for dealing with my father’s sisters daughter are quite different to dealing with my father’s brother’s daughter.) A Groote Eylandt Aborigine not only needs to know who someone is before knowing how to deal with them they also need to know how the person is related to a number of people.
Recently I heard a linguist say that the Aborigines of Botany Bay used different languages in different social settings.
Army units spoken of by Graham Bell are classified as hierarchical networks. But how much more effective are they if they become also social networks?