How big is BIG?

Having come across a couple of articles recently on village sized communities I have dusted off some writing I did a while ago on group size.
If you search for information on human group sizes you will very quickly come across the work of Robin Dunbar, head of the Social and Evolutionary Neuroscience Research Group in the Department of Experimental Psychology at  Oxford, whose book Grooming, Gossip and the Evolution of Language contains reports of detailed research on primate and human group size from various scientific disciplines. The main thrust of his view is that optimum size of social groups is linked to the size of the neocortex, the newest and so-called ‘’thinking’’ part of the brain. Our closest primate relative the chimpanzee lives in social groups of 30-50 – the human neocortex is four times bigger than that of the chimpanzee. From this information Dunbar predicts that the average/optimum human group should number 147.8, or about 150. He then looked for human social groups that might support his thesis and he found the number reoccurring all over the place.

In a survey of 21 different modern hunter-gatherer tribes around the world, who presumably reflect some elements of our ancestral past, he found that the average number of people in each village was 148.4. A study he came across commissioned by the Church of England had concluded that for a congregation to be large enough to support the activities of a church, yet small enough for everyone to know everyone else sufficiently well to form a close-knit, mutually supportive community the ideal size was 200 or less. He found a similar pattern in military organizations. From the Romans onwards through trial and error, military planners have arrived at a rule of thumb for the size of a functional fighting unit somewhere between 100 – 200 men. Numerous military commanders have come to the conclusion that it becomes increasing difficult to make any group larger than this function as a unit without complicated hierarchies, rules and regulations to insure loyalty and unity within the group – and that coming from somewhere already seemingly hidebound with rules and hierarchy.

More pertinent to the discussion of the size of intentional communities is perhaps the case of the Anabaptist village communities of the Hutterites. the Amish and the Bruderhof in the USA and Britain. Traditional Hutterite colonies average about 90 persons in a colony, Amish church districts have on average about 160 persons while the Bruderhof maintain the largest domestic units of the three, with communities ranging from 160 up to 300 adult residents. All these groups attempt to maximize community harmony by keeping their numbers ‘small’, “small enough so that all of its members are needed for all of its enterprises.”
imagesBTJA3QG7The Hutterites and the Amish have the most ordered method of community sub-division. Every time community membership approaches 150 or so, it is divided into two separate groups. They have found that once a group becomes larger than that, “people become strangers to one another.” At 150, the Hutterites believe, something happens that somehow changes community dynamics seemingly overnight. At around 150 members communities spontaneously begin dividing into smaller ‘sub-groups’, a process which eventually undermines community harmony. The Amish talk of an optimum community as one where “people can know each other by name, by shared ceremonial activity and convention.”

Darvell Bruderhof Robertsbridge Kent
Darvell Bruderhof Robertsbridge Kent

The Bruderhof, or Society of Brothers, present a slightly more complicated case for the magic Dunbar-number. Although they follow the general rule of dividing communities when they reach a certain size this is usually at a higher level than either the Hutterites or the Amish. This may be why they seem to have had more periods of internal conflict in the recent past than the other two groups (thus supporting the Dunbanumba thesis). However the other strand of Professor Dunbar’s thesis is that our brain size, the roots of human language, human group size and our evolution from apes is all primarily due to our ability to build and maintain relationships through gossip. It may even be possible that 150 is the size of the network that can be maintained by gossiping or informal inter-personal small-talk.

The Bruderhof throw a spanner into this theory by having a rule of “no-gossiping” dating from the early history of the group in Germany, has remained a fast rule. There will be no gossip. No talk about others behind their back. Any member who hears gossip must immediately challenge the gossiper to repeat his statements to the subject’s face. Such talk must be reproved as evidence of wrong attitudes. The offender must confess the sin and humbly ask forgiveness. Otherwise he or she may be excluded from worship and group meetings, possibly with the imposition of even greater sanctions.
The Bruderhof aside Robin Dunbar’s conclusions about human group size remain remarkably convincing

“ … human societies contain buried within them a natural grouping of around I50 people … they are a consequence of the fact that the human brain cannot sustain more than a certain number of relationships of a given strength at any one time. The figure of 150 seems to represent the maximum number of individuals with whom we can have a genuinely social relationship, the kind of relationship that goes with knowing who they are and how they relate to us. Putting it another way, it’s the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar … it seems that, even in large-scale societies, the extent of our social networks is not much greater than that typical of the hunter-gatherer’s world … ”  Robin Dunbar. Grooming, Gossip and the Evolution of Language.


Professor Dunbar also came across other ‘magic’ numbers. From; ‘clan’ sized groups of typically 1500 – 2000 people, through ‘bands’ of 30 – 35 people essentially collaborative groups of families who find it convenient to come together to pool resources, to a cluster of human groups with 10 to 12 members known as sympathy groups. A sympathy group is the number of individuals that it is suggested we are able to maintain very intense relationship with at any one time. Studies asked people to list the names of their intimates – those friends and relations whom they contact at least once a month – the answer being typically 10 to 12. They also asked people to list the names of everyone whose death tomorrow they would find devastating; again the answer is about 10 to 12. Groups in society where very close co-ordination of behaviour is required are commonly about this number: juries, the inner cabinets of many governments, the number of apostles, witches covens, the size of many sports teams.

Another magic human group number banded about, this time by management gurus and the like, is the ‘action-taking group’, usually having five members. Kirkpatrick Sale in Human Scale makes the case for this being the smallest effective human group – drawing on evidence from far and wide – from the size of hunting bands in early Paleolithic societies (“Usually no more than five”), the size of early Greek ships crews and the number of people it takes to make a conspiracy. More convincing is the evidence he quotes from various management studies. The Handbook of Small Group Research suggests “that the optimal committee size is five, since below that number people tend to feel that getting together is “not worth it” and “won’t prove anything,” whereas much above that people start to participate less and eventually stop paying attention.”

Another study showed that groups between four and seven were “ most successful at solving problems, and that as groups increase in size they tend to take more time to come up with solutions, make less accurate judgments, produce fewer ideas, achieve less communication, and stand less chance of reaching an agreement.” Another researcher observed that most committees “start with; five members-before that there is not enough sense of cohesion for the group to consider itself a committee at all-and after a time, when they grow and become unwieldy with new members, they tend to revert to the original size by establishing an “executive committee” or “board of directors,” or some such …”

“for best participation, for highest all-round involvement, a size between five and seven seems to be optimum.”       Charles Handy. Understanding Organisations. Penguin 1976

UK Intentional community size
A quick survey of the sizes of intentional communities in the UK taken from figures in the eight editions of the Diggers & Dreamers Directory covering the years 1990 through to 2004 gives clusters of ‘action taking’ and ‘sympathy’ type groups – Just under a third each of the total communities for which population information is available. With groups having more than 15 members being evenly spread, although of the small number of communities with over 50 members there is a clustering around the figure 150. All of which would seem to give additional weight to Robin Dunbar’s ideas.
But do any of these numbers give any helpful pointers when it comes to trying to sort out what the optimum size for any intentional community might be?

Well …
• if you’re looking to be an activist-orientated-action-taking communal house with a quick-creative-decision-making-process, that has high all-round involvement and maximum participation, then you should be aiming for a membership of five to seven to be most effective.
• If you want a community that maintains close interpersonal relationships between all its members then a membership of around twelve would seem to be what you should be looking for.
• Whereas if what you want is to live in a Cohousing type scheme with a collaborative group of families that have to come together to pool resources then you need to get together with thirty odd other people.
• And if what you are really after is an all-together looser network type community, where you can stay in touch with what’s going on by gossiping over the eco-village fence, then when your population nears the magic hundred & fifty consider starting another community!

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