Dunbar's number: is it true that we can't have more than 150 social connections?
Miscellaneous / / May 17, 2023
This theory has many fans. But it was not without criticism.
Imagine that you are a monkey. What would you do to please your relative? Would you give me a banana? No, that won't work: the fruits we eat are not component of the diet in any of the monkey species. So the love of primates for bananas is as much a myth as the passion of mice for cheese.
In fact, the most common way monkeys spend time together is looking for fleas. This is called social grooming. Males do it to courtship and romance, individuals of the same sex to make friends, and adults comb the fur of the cubs to strengthen parental bonds.
Social grooming interested British anthropologist and evolutionary psychologist Robin Ian MacDonald Dunbar. And this led to the creation of a whole theory.
What is the Dunbar number
In 1992, Dunbar decided to figure outwhat does size have to do with brain primates to their ability to form social bonds. And he began to calculate how often different types of monkeys comb out each other's fleas.
In the end, he found a correlation between the number of social bonds that primates can maintain and the volume of their neocortex. This is an area of the cerebral cortex responsible in them for higher nervous functions, and in people - also for thinking and speech.
It turned out that the larger the neocortex, the easier it is for a primate to establish contact with its relatives with the help of grooming.
Accordingly, it is easier for such individuals to organize themselves into groups - it is more convenient to defend themselves both from predators and from other similar monkeys.
Dunbar studied 38 species of primates, mathematically establishing a correlation between brain size and the number of social connections that his subjects made. And then I decided extrapolate results on people.
It turned out that the owner of the average human brain can have about 148 stable social connections. The number was later rounded up to 150 for simplicity. This is Dunbar's number.
Trying to explain his idea in a simpler way, the researcher declaredthat 150 is "the number of people you could sit down and drink at the same table without embarrassment after bumping into them at a bar."
What makes up this number
Later Dunbar expanded his conclusions and suggested that social ties are divided into types depending on how closely we know people from a particular group.
- Best friends and family - about 5 people. These are the ones we spend the most time with and feel especially close to. With them we can share our secrets and get support.
- buddies - about 15 people. We are in close contact with them, but not as much as with people from the first group. We do not expect the same understanding from them, but they are still glad to see us.
- Colleagues, distant relatives, acquaintances - 35-50 people. With these people we intersect situationally, but regularly. For example, at work, in hobby groups, at family holidays.
- Active social network - about 150 people. This is the maximum of people whom we can remember enough to keep abreast of their lives, more or less imagine their character and immediately recognize them by sight. This group is called the "Dunbar number".
- The people we remember - about 500 people. Those with whom we have communicated in the past and can remember their existence, but do not keep in touch. To this (and the next) group, you can also attributed your friends from social networks.
- People we know by name but not personally - about 1,500 people. It can be not only a colleague from a neighboring department, whose existence you heard, but also Elon Musk, Taylor Swift and other celebrities.
dunbar thinksthat the number of people in each such "layer" usually does not exceed the indicated values. But people from the previous group are taken into account in the next. That is, the numbers 5–15–50–150–500–1,500 are not summed up, but “embedded” into each other.
How does Dunbar's number relate to language?
According to Robin Dunbar, the most socially active primates can have as many as 80 friends and acquaintances. In humans, this figure, as we understand it, is approximately equal to 150. Why is that?
Monkeys, according to the researcher, make friends in an extremely inefficient way - by looking for fleas from each other. And in order to gain 150 or more acquaintances, they literally have to comb out parasites in their relatives half of their free time. As a result, they simply will not have time for food and sleep. So 80 is a monkey ceiling.
People have come up with such an effective way of communication as language.
And our verbal communication allows us to express much more than the caresses of monkeys, and at the same time spends less time.
Robin Dunbar calculatedthat if we couldn’t speak, we would spend 42% of our time combing the hair of friends and caring for each other in other ways. It is obvious that such a civilization could hardly invent fire, wheel, coffee grinder and James Webb telescope.
What evidence does this theory have?
Dunbar found in support of his theory a lot examples from the history.
The human neocortex formed in its current form during the Pleistocene epoch about 250,000 years ago. At that time, hunter-gatherer communities consisted of 100-200 members, which is roughly the number of Dunbar.
About 150 farmers lived in an average Neolithic village. The main military units of the armies of the past, such as Greek and Roman, were an average of 150 people. 150 inhabitants was the average for villages in the counties of England of the era Middle Ages.
Dunbar notes that a community of 150 people will tend to stick together, and if it grows, then will fall apart into separate groups.
Where is the Dunbar number used?
After the publication of Dunbar's work, journalists replicated the results of his research, simplifying the scientist's calculations to the conclusion "the maximum number of friends you can have is 150." Entrepreneurs and HR managers have found this data useful from a practical point of view, and some companies and startups have begun to use the Dunbar number to form their teams.
Writer and journalist Malcolm Gladwell in his book "Crucial momentdescribes the example of WL Gore and Associates, now Gore‑Tex. Managers determined through trial and error that its employees work best if there are no more than 150 people in one branch. They become united and friendly. And if their number increases, all sorts of small problems begin and conflicts.
So Gore‑Tex is building corporate buildings with 150 employees and 150 parking spaces.
And when the number of employees exceeds the limit, the firm simply creates another branch nearby.
True, the company's managers forgot that Dunbar's number includes not only colleagues, but also relatives, relatives and comrades of interest. Perhaps they assumed that their employees had no families or friends.
Dunbar's number is also used by social media developers. It helps they need to calculate what server capacity will be needed to support a certain number of virtual "friends", and it comes in handy when designing interfaces.
Why Dunbar's Number Is Criticized
This concept has become extremely popular among people who are fond of popular psychology. But it also has its critics.
For example, anthropologists Russell Bernard and Peter Killworth conducted a series research, trying to replicate Dunbar's results. And they had an average of 290 social connections maintained by a person, about double the original results. True, their works did not receive much distribution.
Scientists from Durham University in the UK criticized Dunbar's work for deriving his number by extrapolating from monkeys on people. However, in the latter, sociality is influenced not only by the volume of the neocortex, but also by the cultural environment, position, and many other factors that the researcher did not take into account.
Philip Lieberman, a cognitive scientist at Brown University, argued that the average Paleolithic hunter-gatherer group size was 30–50, and considered the estimate of 150 to be too high. He wrotethat the limiting factor here is not the volume of the neocortex of its representatives, but the amount of food that they could get.
In addition, scientists from New York University figured outthat brain size in primates is determined primarily by diet, not sociality. Chimpanzees, who eat meat infrequently, and gorillas, who prefer a vegetarian diet, have far fewer resources to grow the same developed brains as Homo sapiens.
And researchers from Sweden rechecked Dunbar's work and suggested that his conclusions are both theoretically and empirically unfounded. Their average number of permanent social connections ranged from 4 to 520. Anthropologists in general, they doubted the possibility of deriving a number common to all people: the spread is too big.
In general, it is simply impossible to unambiguously confirm or refute Dunbar's theory. So it's up to you to believe in a beautiful number or not. But if you are a business owner, then creating branches with no more than 150 employees is not a bad idea.
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