A large group of around 150 participating adults (for a summary table of key group sizes see Groups and Group Sizes).

In the history of cooperation, there has been much agreement on the effectiveness of groups on this scale. The number is suggested, for instance, by the frequency of the 150-person group in industry. “Compartments” of this size, writes Gerald Fairtlough, have a quality of communication which is “open, intensive, subtle and varied, which could not happen on a larger scale”:

There is a clear boundary marking off compartment members from non-members and a strikingly different expectation about openness, trust, shared purposes and shared language inside the boundary, compared with expectations across it. [This size of group can] create great creative energy in achieving a common aim, in carrying out a common project, in solving a common problem. It can assemble a rich blend of skills and knowledge, giving it the potential to produce extraordinary results . . . On such a scale, and in the right conditions, the creative capability of human beings is unlocked—perhaps to an unimaginable extent.N82

There are many examples of groups of this size. One comes from the Hutterites—the Christian community of agriculturalists (similar to the Amish) now living in the Dakotas and southern Canada. For more than four centuries, they have successfully sustained communes with an upper limit of about 150 members, plus their families. They do not allow private property, so they pay no wages, but members qualify for the material benefits of membership whatever they do. As a consequence, the only incentives their members have to pull their weight are their conscience and sense of solidarity. They accept that there will always be people who try to get out of doing the work—they have a saying, “All colonies have their drones”—but solutions are at hand so long as the group remains small: the elders have a quiet talk with them; their fellow colonists encourage them. In a small community, members are ready to recognise their obligations, and prepared to listen to other members who point them out, but if it is allowed to grow larger than around 150 people (about 30 families), the drones multiply, and the colony is forced to split up.N83

This a matter in which there are fuzzy boundaries. For instance, some groups of 150 (such as the army company) are single sex, but the historian Peter Laslett includes both adult men and women in his estimate that 150 was the median size for an English village in 1700.N84 Nearly three centuries later, Ronald Blythe claims that the village he studied, Akenfield, tended to organise itself into informal groups of about that number.N85 The critical point is that 150 is the maximum number with whom you—as a member of the group—can actually engage, cooperate and reciprocate: you know the internal politics; who belongs to which small group; how the lines of influence and leadership run. For the larger community as a whole, if each of the members of the 150-group represent one family, that will allow a community size (including children and the elderly) of some 500–600. But the core network of close interactions holds. 150 is the number of active characters you can cope with in the group before engaged interaction begins to fade into mere acquaintance.

And the crucial role of the 150-group is borne out by the work of the anthropologist Robin Dunbar. As in the case of the size of primary groups (your closest friends and family: see Small Group), Dunbar was able to show that there is a correlation between primates’ neocortex ratios (the ratio between the size of the neocortex and the size of the rest of the brain), and the size of the neighbourhood-scale coalitions which are the foundation of their social standing.

This correlation is trickier than it may seem. Since the neocortex is the part of the brain that can process the politics of multiple interactions, the large neocortex ratio is needed to understand and deal with the complex relationships in the small group. Clear enough so far, but Dunbar argues that the larger the small/primary group you belong to, the larger the secondary group you can make your way in, which is why the neocortex ratio is associated with both group sizes. If you have the benefit of belonging to a relatively large, closely-bonded primary group of friends and allies, this power base makes it possible for you to survive and prosper in a relatively large secondary group: if you are on your own in a troupe of gelada baboons or in a neighbourhood of human primates, it is hard for you to defend your interests. A primary group of close friends puts you in a tenable position in the secondary group/troupe/neighbourhood.

Dunbar demonstrates this by testing the scale of 150 against the neocortex ratios, and finding that primates with larger neocortex ratios do in fact live in larger groups. Those with the lowest ratios (1:1) are minimally socialised, living essentially solitary lives, but primates with a ratio of 3:1 live in groups of about 15. He then applies this correlation to the case of humans, with their neocortex ratio of 4:1, and shows that this corresponds to a mean (secondary) group size of 148 (see figure).N86 He summarises,

Taken together, these results suggest that human societies contain buried within them a natural grouping of around 150 people. These groups do not have a specific function: . . . 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.N87

150—all lines of enquiry seem to lead to this number as the optimum size of the neighbourhood-community—plus families. And yet, just as twelve seems too many to be a realistic small group in action, so 150 is too many for day-to-day business. It is, rather, an immediate local resource to be called on: it can bring substantial numbers—such as the 35-member groups which Dunbar describes as “overnight camps”—to a common project; or it can all come together for policy-making and changing locations; or for identity-building with parties and ritual. The neighbourhood is the household’s setting, protection, labour-resource and store of capital.N88

This is what specialists in animal behaviour would call a “fission-fusion” social system, with flexibility, coming-and-going and kinship links both within and between communities.N89 The task determines the size of groups within the neighbourhood, but cooperation in the community grows out of the sense of living together, and the shared strengths, weaknesses, opportunities and threats that can be sustained between about 150 people and their families.


What the neighbourhood does

The neighbourhood has four functions. First, it has a material job to do. It is an active agent for lean production—for community-wide conservation and the provision of renewable energy; for local food, water and waste management and the conservation of fertility; and for the provision and management of materials.

Secondly, it has a political function. It defends the interests of its people in a fiercely political wider world. Small groups may well be able to speak for themselves at the parish level, but it helps if they have a solid power base of support from their neighbourhood. Politics is about having allies.

The third function is social. The wider community is needed for the more elaborate ceremonies and religion, for carnival, for people seeking discussion with specific matching professions, talents, interests or expectations, and for courtship, but in the neighbourhood there is conviviality, and it is the place where the basic skills of society and culture are learned—a setting for fun, exuberance, play and parties. Neighbourhoods—their internal politics and their relations with each other and with the wider community—are the starting point, the power base, from which to participate in the community and the public sphere. They are ambivalently located with respect to the public and private spheres, but they have known you since you were little, and they care if you go away. They are where home is.

The fourth function of the neighbourhood is as an enabler of events. In the future, it will be larger groups on the scale of the wider community or parish—or the parishes in a town—which take the initiative, as we are seeing with Transition Towns. But it is not really the parish that does the work; that comes from smaller groups, especially the neighbourhood. When sustained application is needed, the community inspires it; the neighbourhood does it; the household lives it.


Related entries:

Reciprocity and Cooperation > Collaboration.

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David Fleming
Dr David Fleming (2 January 1940 – 29 November 2010) was an economist, historian and writer, based in London. He was among the first to reveal the possibility of peak oil's approach and invented the influential TEQs scheme, designed to address this and climate change. He was also a significant figure in the development of the UK Green Party, the Transition Towns movement and the New Economics Foundation, as well as a Chairman of the Soil Association. His wide-ranging independent analysis culminated in two critically acclaimed books, Lean Logic and Surviving the Future. A film about his perspective and legacy - The Sequel: What Will Follow Our Troubled Civilisation? - was released in 2019, directed by BAFTA-winning director Peter Armstrong. For more information, including on Lean Logic, click the little globe below!

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