An individual human can maintain stable social relationships with around 150 people. This is the proposition known as the “Dunbar number” – that the architecture of the human brain sets an upper limit on our social lives. A new study from Stockholm University indicates that a cognitive limit on the size of human groups cannot be derived in this way.
Dunbar’s number is named after British anthropologist Robin Dunbar, who proposed the theory in the 1990s. The number 150 is based on an extrapolation of the correlation between the relative size of the neocortex and the size of groups in primates non-human. Some empirical studies have found support for this number, while others have reported other group sizes.
“The theoretical basis for Dunbar’s number is fragile. The brains of other primates don’t handle information exactly the way human brains do, and the sociality of primates is mainly due to factors other than the brain, such as what they eat and who their predators are. In addition, humans have a great variation in the size of their social networks, ”says Patrik Lindenfors, associate professor of zoological ecology at Stockholm University and the Institute for Futures Studies, and one of the authors of study.
When Swedish researchers repeated Dunbar’s analyzes using modern statistical methods and updated primate brain data, the results were simultaneously much larger and well below 150.
The maximum average group size has often been found to be less than 150 people. But the main problem was that the 95% confidence intervals for these estimates were between 2 and 520 people.
“It is not possible to make an estimate for humans with any precision using the available methods and data,” says Andreas Wartel, co-author of the study.
Dunbar’s issue is often cited and made a big impact in popular culture, especially after it featured prominently in Malcolm Gladwell’s book “The Tipping Point”. In 2007, Swedish media reported that the Swedish tax administration had reorganized its offices so as not to exceed the limit of 150 people.
“This reorganization would then be based on the implicit but hopefully unintentional assumption that their employees have no family or friends outside of work,” says Patrik Lindenfors and adds: “I think Dunbar’s number is largely widespread, also among researchers, because it is so easy to understand. Our claim that it is not possible to calculate a number is not so entertaining “
Ideas like Dunbar’s number highlight questions about the long range of the gene.
“Are human social interactions genetically limited by the influence of genes on brain architecture? New research on cultural evolution has revealed the importance of cultural heritage for what humans do and how we Let’s think. Culture affects everything from the size of social media to whether we can play chess or whether we like to hike. Just as someone can learn to remember a huge number of decimal places in the pi number, our brains can be trained to have more social contact, ”says Johan Lind, deputy director of the Center for Cultural Evolution at Stockholm University and co-author of the study.
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