All you want to know about Dunbar's Number: From Prehistory to 21st Century Enterprise

A highly connected environment sustains the Organization (or any group’s) vitality. But it’s not possible to keep up a good relationship standard with everyone. Oh! Let’s NOT consider Facebook or LinkedIn or any other social medias. We have friends, family, and colleagues included in our social connection list, but 80% of that are the general population who accumulated under a typical interest, objective and may not be close enough or semi-strange to you.


This story goes way back into the 90’s! The British anthropologist and the creator of “How Many Friends Does One Person Need?” acclaimed humans can agreeably maintain only 150 meaningful relationships. The prediction led the world over scientists, researchers into a huge wave of new discovery and evolution.

According to Robin Dunbar, the Correlation between Human Biology and Social behavior has a greater influence on sustainable relationships. The reasons are quite basic!! Connection, Communication, Shared expectation - all these Systemizing words don’t bode well if we can’t even recollect the faces.

Bigger brains = Stronger memory power = Huge social gatherings

Why 150? You must be thinking I can have more or less than that, perhaps 200 or 120 or 380. If you actually give it a thought, the point does make sense. Analyzing from the size of an average human brain, the number of people we probably could have in a social group is around 150. Anything beyond that would be too much to handle. For example; try remembering the faces, occupations, and natives of the people around you (like from your social list or in your organization or relatives or distant relations). I think now you understand what I am trying to say. Not many faces you can remember or much information you know about them.

The other explanation for the shared (I-care-you-give it a second thought) relationship is time. It’s obvious, relationship development needs time. Not having enough time makes the emotion and interest dull on both sides. Regardless of the fact that the Dunbar's number sounds bit imprecise, however, having more than 150 close connections sound more unrealistic. 


 From Red Cliffs of Dawlish


Even though the cognitive limit of Dunbar’s number is 150 (commonly used value), it can be varied between 100 - 250  or 30 - 50 or 500 - 2500 in the case of the variance in group’s  culture, law, lineage, character and many other conditions. Let’s talk about the different conditions that will come with Dunbar’s strategy to exemplify true social relationships:

Historic evidence of Dunbar’s Number

Dunbar did many historic explorations about Social evolution, grooming, and the Utopian society. He found 250,000 years prior, amid of the Pleistocene era, hunters and tribes classified into small, medium and large groups.

Small community - 30 to 50 - typical members of a close-knit band with a common interest of hunt.

Medium community - 100 to 200 members - gathering of individuals with a cultural lineage or kinship (Note 1: Kinship refers to man’s basic duty in a society, like - finding a partner, marriage, parenting, socialization, siblingship etc.)

Large community - 500 to 1500 - this gathering could be counted as one tribe (Note 2: They follow their ancestral culture, beliefs of unity, laws, and rights. They are self-sufficient and had strong emotion towards their lands. It is also a gathering where you could see the different characteristics, leadership conflicts, cultural evolution and colonialism)

When Dunbar analyzed these anthropological records, he found the average group size of the prehistoric society was (148 rounded as 150) individuals. He likewise found the mean size of Neolithic (New Age Stone) groups, which were around Hundred and Fifty. I think the number had advantages over other size groups due to the constant shifting from places to places in search of good farming land and domestication, since most parts of their livelihood depended on Subsistence agriculture (Self-sufficiency farming).

Dunbar’s number and Modern Society Emotional ties

Dunbar has predicted the magic numbers for the size of groups according to a man’s emotional behavior.

The size of 5 - The closest relationships you have (family, best friends, partner, or siblings). They are the ones with whom you have the strongest emotional closeness and support you the most.

The size of 15 - The friends with whom you are very much open about your life. Even if you don’t see them constantly, you do care for them and sympathize with them. For example A Whatsapp chat group only of your few childhood friends or few ex-colleagues with whom you have been in touch frequently for years.

The size of 50 - The group of people you can call friends or acquaintance, whom you properly know about. But they are not enough to close to call close friends. You can hang out with them or invite them to your functions, but you wouldn’t feel emotionally alone in their absence.

The size of 150 - This group can range from 150 to a very large number. A group of people you hardly know about (I mean their faces, how they are related to you or some minor information)


This whole idea of analyzation is known as “Dunbar’s layers” for cumulative relationships. We all have primary (essential) and secondary (optional) connections with people around us. Our desire to get more influence, riches, fame sometimes makes us move forward by abandoning that essential supportive circle. So, we should find a way to give 80% of our time to nurture those relationships. 

Dunbar’s Number in Roman legions

The average size of historic military troops were 150, says Robin Dunbar. Not only the Roman legions, but the idea got acknowledged by countries like old Spain and the Soviet Union. The trend was also implemented in World war 2.

Let’s discuss about the number of groups the World War Two & Roman military were divided into:


World War 2    


  Roman namings    


A section

  4 to 12



The smallest subunits that helped for support of the major groups and doing


A unit

50 to 80

 Heavy  infantry


Wielding weapons of iron helmets, javelin, shields (foot soldiers)

A company

120 to 250



Tactical units with weapons and (sometimes mounted)


A battalion

450 to 1000



Organized, mounted, high - class young soldiers (mostly from extinguished families)

A Regiment


1500  to ...



Consists of many cavalries,

The biggest unit

These numbers are a little smaller or larger than the Dunbar layers, however, in the natural range of variation.

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