An individual human can maintain stable social relationships with about 150 people. This is the proposition known as ‘Dunbar’s 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 human group sizes cannot be derived in this manner.
Dunbar’s number is named after the 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 group sizes in non-human primates. Some empirical studies have found support for this number, while other have reported other group sizes.
“The theoretical foundation of Dunbar’s number is shaky. Other primates’ brains do not handle information exactly as human brains do, and primate sociality is primarily explained by other factors than the brain, such as what they eat and who their predators are. Furthermore, humans have a large 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 the study.