Is Social Group Size Limited to a Specific Number?


Is Social Group Size Limited to a Specific Number?

A distinguished and enduring anthropological notion, analyzed cognitive limit on a human to maintain stable social relationship with only 150 individuals is known as Dunbar’s number, presented by a specialist in primate, anthropologist, and evolutionary psychologist, Robin Ian MacDonald Dunbar. He noticed the correlation between the brain’s neocortex and the social group size of primates and thus defined Dunbar’s number.

The discourse of human social network has given rise to many different schools of thought and Dunbar’s number is one of those. Many studies have replicated Dunbar’s number but the findings weren’t always significant, as the studies had many limitations. For many researchers like those from Stockholm University, including Patrik Lindenfors, famous Dunbar’s number doesn’t add up, mainly because it lacks theoretical foundations.

Modern scientists are skeptical about these numbers because not all primates handle and process information exactly asa human brain does. Other factors can influence sociality in primates like their habitat, the food they eat, and the type of their predator. For Dunbar’s number, it is the volume of the neocortex (number of neocortical neurons) that is related to the brain’s function as a limiting factor on the size of their social group. Dunbar was of the view that neocortical neurons and primate’s information-processing ability are directly related, therefore a rise in group size, strains the cohesive social unit and makes it unstable.

Pakistan Journal of Biological Sciences

Patrik Lindenfors scrutinized the statistical basis of ‘Dunbar’s number’, and analyzed it based on complementary datasets to verify the claim that neocortex size in primates is equally pertinent to human socialization parameters His team tried to make a decisive deconstruction of the empirical basis of Dunbar’s number by phylogenetic comparative analysis of Dunbar’s number with Bayesian and generalized least-square, on a huge dataset of correlation between group size and both relative brain size and neocortex size to estimate cognitive limit in humans. They found that their calculation of human group size is variable, depending on the method or variable choice. They emphasized that the number’s that Dunbar suggests are just an average and not an upper limit. To draw the value of the upper limit, a better approach with a 95% confidence interval should be selected. Because, when the Lindenfors team selected the confidence interval of 95% variable estimates were observed, thereby indicating an upper limit far exceeding 150, every time.

Some researchers believe that specifying just one number is pointless and unreliable, as Dunbar’s method of calculation of cognitive limit in humans and primates cannot be calculated by this approach. As there are many other socio-ecological components are involved in defining social circle and not just the brain’s volume or numbers of neurons.

Dunbar’s number also didn’t take into consideration the fact that not all primates are like humans physiologically and anatomically. Their social structures and cultural developments differ greatly. Ecological researchers believe that there is no fixed cognitive limit on humans socially, because of the uniqueness of human thinking and their observational skills. The social media platforms have challenged Dunbar’s number’s upper limit and it has been proved several times.


Dunbar’s numbers, primates, neocortex, Neocortical neurons, cognitive limit, anthropology.