“150” is often referred to as “Dunbar’s Number.”
Dunbar’s number has been observed in various aspects of human society. The group size suggests a cognitive limit for relationships.
The number 150 emerged from studies of social group sizes in various societies, as well as in non-human primates, and from the ratio of neocortical volume to the total brain size. 1Dunbar, R. I. M. (1992). Neocortex size as a constraint on group size in primates. Journal of Human Evolution, 22(6), 469 – 493.
For instance, military units have often been organized around this size, and some businesses have used it as a guide for structuring their organizations.
Here we go:
Dunbar’s Number: 150 Relationships
150 — Dunbar’s Number
Robin Dunbar, a British anthropologist and evolutionary psychologist, proposed what’s known as “Dunbar’s Number” — a theory suggesting that humans can only comfortably maintain about 150 stable relationships. 2Dunbar, R. I. M. (1998). The social brain hypothesis. Evolutionary Anthropology: Issues, News, and Reviews, 6(5), 178 – 190.
This includes family, friends, colleagues, and others with whom a person can keep meaningful contact. Beyond this number, the quality of relationships can diminish due to the limitations in our mental bandwidth. 3For more on different social group sizes, see also “Group Sizes (From Support Cliques to Tribes).”
“Dunbar’s number is a suggested cognitive limit to the number of people with whom one can maintain stable social relationships. […] No precise value has been proposed for Dunbar’s number. It has been proposed to lie between 100 and 230, with a commonly used value of 150. Dunbar’s number states the number of people one knows and keeps social contact with, and it does not include the number of people known personally with a ceased social relationship, nor people just generally known with a lack of persistent social relationship, a number which might be much higher and likely depends on long-term memory size.”
— Wikipedia 4Dunbar’s number. (2023, May 29). In Wikipedia. https://en.wikipedia.org/wiki/Dunbar%27s_number
According to Dunbar, this limit is a direct function of relative neocortex size, which constrains our ability to keep track of complex social relationships. 5It’s worth noting that the concept of Dunbar’s Number has also been a topic of debate and scrutiny within the scientific community.
Learn more: 150 — Dunbar’s Number
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Group Size Examples
The concept of Dunbar’s number, around 150, has been observed in various social and organizational contexts.
Here are some examples:
These are only approximate values; the actual “Dunbar’s Number” can vary from person to person or from context to context. But they suggest a general human propensity to form and maintain stable social relationships up to about this number.
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PR Resource: Typical Social Group Sizes
Typical Social Group Sizes
How many social connections you you comfortably sustain? According to the social brain hypothesis, limits exist. 6Zhou WX, Sornette D, Hill RA, Dunbar RI. Discrete hierarchical organization of social group sizes. Proc Biol Sci. 2005 Feb 22;272(1561):439 – 44.
“The ‘social brain hypothesis’ for the evolution of large brains in primates has led to evidence for the coevolution of neocortical size and social group sizes, suggesting that there is a cognitive constraint on group size that depends, in some way, on the volume of neural material available for processing and synthesizing information on social relationships.”
— Discrete Hierarchical Organization of Social Group Sizes
Scientific evidence suggests that people tend to organise themselves not in an even distribution of group sizes but in discrete hierarchical social groups of more particular sizes:
Alas, there seems to be a discrete statistical order in the complex chaos of human relationships:
“Such discrete scale invariance could be related to that identified in signatures of herding behaviour in financial markets and might reflect a hierarchical processing of social nearness by human brains.“
Source: Discrete Hierarchical Organization of Social Group Sizes
Read also: Group Sizes (The Social Brain Hypothesis)
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ANNOTATIONS
1 | Dunbar, R. I. M. (1992). Neocortex size as a constraint on group size in primates. Journal of Human Evolution, 22(6), 469 – 493. |
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2 | Dunbar, R. I. M. (1998). The social brain hypothesis. Evolutionary Anthropology: Issues, News, and Reviews, 6(5), 178 – 190. |
3 | For more on different social group sizes, see also “Group Sizes (From Support Cliques to Tribes).” |
4 | Dunbar’s number. (2023, May 29). In Wikipedia. https://en.wikipedia.org/wiki/Dunbar%27s_number |
5 | It’s worth noting that the concept of Dunbar’s Number has also been a topic of debate and scrutiny within the scientific community. |
6 | Zhou WX, Sornette D, Hill RA, Dunbar RI. Discrete hierarchical organization of social group sizes. Proc Biol Sci. 2005 Feb 22;272(1561):439 – 44. |