Apple and Orange I have been thinking about how size can affect culture and adaptability of groups recently. The topic once again came up today in a talk about what makes a healthy community. The answer to that will depend on the community's size and maturity. An open source project, in the words of one participant in one conversation I had recently on this subject, should have "the minimum level of structure to allow it to function effectively." I agree—just enough is the right amount. This article contains some ponderings on the relationship between size and communities, and some conclusions we can take from that.

Size and Culture

I have been thinking of this because of a few converging issues—one project I work on, which started with four people, now has more activity than we can handle, and we are thinking of how to grow the group of (OpenStack style) committers. I have been helping another project figure out how to create a governance structure to allow them to grow effectively beyond their current size, where they have about 10 active companies and about 150 active developers. And the company I work for has been going through some growing pains as we go past 10,000 people in size.

The work of Robin Dunbar comes to mind—he of Dunbar's Number. In How Many Friends Does One Person Need?, he examines the nature of communities of different sizes. He finds a number of group sizes that recur often, and their characteristics change at certain size limits: The specific sizes he points to are 5, 15, 50, 150, 500, and 5000—he suggests that there might be something special about this scaling factor of three. But he does not talk a lot about evolution—how group dynamics change as the groups grow. A few examples occur to me from my own experiences:

  • One small company I worked for used to have a monthly dinner with all staff and their partners—possible when there were five or six employees and 8 or 10 people at dinner, but that gets more difficult as you get bigger.

  • Another company, we were between 15 and 30 employees while I worked there—every morning, everyone, when arriving, used to say good morning to everyone else in the company. At some point (around 20 people), people stopped doing that, and just said hello to the people they met on their way to their desk, and the people in their immediate office.

  • As mailing lists grow, the peer pressure to respond personally to any individual message diminishes. At a certain size, it becomes much more difficult to evaluate the authority level of a person posting on the list, and the social ties weaken between list participants. On one list I participated in, when the main list got too busy, they created a "developers" mailing list where they could hang out together. A similar phenomenon happens with IRC channels.

  • I remember talking to a friend who was the founder of a growing tech company, who told me about the first time his company hired someone he had not personally interviewed—my recollection is that it happened after the company passed 50 employees, but before it hit 70. Around the time the company had 50 people, the overhead of interviewing and hiring new people grew beyond his ability to scale.

There are multiple other scaling events—when do you implement some kind of HR process for absence management, expenses, pay raises, and so on? How big are you when it becomes cost effective to hire a full time accountant, lawyer, administrator, talent acquirer? When is a single team in your company big enough that you need to hire or promote someone who is not a founder to management? How big before it is unreasonable to ask everyone's opinion on a work change that impacts everyone?

These events are specific to companies, but communities have similar scaling experiences. At some point, the project maintainer will not be personally reviewing all changes to the project. Tools and process will need to be added for managing bug reports, releases, automated builds, source control. As the project gets bigger, you will hit a point where it is more work than volunteers can do to maintain infrastructure, and your project may need to budget money for a sysadmin. And if you need budget for a sysadmin, you may be at a point whether it is worthwhile having someone work on fundraising, business development, content management, and other tasks that community volunteers traditionally do not do well.

Structure and Relationships

At each of these changes, required structure and process is one axis. The other axis, perhaps more significant, is how people in the group relate to each other. Individuals can have multiple identities at once, each of which is stronger or weaker. I can be part of a project and part of a company at the same time—and whether I consider myself a project foo developer who gets paid by company X, or a company X employee who happens to be working on project foo, is a very personal thing, depending on the depth of the relationships that I have with other members of the groups "project foo" and "company X."

The relationships with group members will change over time, as group size changes. I started my open source developer career as a developer of the GIMP, spent over a year as the GIMP release manager, and organized multiple GIMP events, but over time I have drifted away as the project evolved, and some of the people I had close relationships with in the project reduced their activity. At the same time as my ties to the GIMP were waning, I was spending more and more time in the GNOME project—and around 2004 or 2005, I would have considered myself more a part of the GNOME project than the GIMP. And so on throughout my career. I have maintained some lifelong friendships with current or former GNOME project members, but that is not such a big part of my identity any more.

There are a number of ways that identity can change as groups grow—and one of them is to break into sub-groups. A Nova developer may still feel like an OpenStack developer, but the personal connections with people working on the Nova project will be stronger. And the Nova core reviewers group will have even stronger relationships with each other. You see this happen with conferences all the time. When a conference starts out, and the number of attendees is in the low hundreds, you have a small number of organizers who are close friends, and attendees have rich relationships and conversations. As a conference gets to the high hundreds, you start to see "tracks" form, where big sub-groups gather to share knowledge specific to them—with a resulting lessening of awareness of what is happening in other projects. When the OpenStack Summit got towards 1500 or 2000 people, you started to see a completely separate sub-event forming for developers—the "OpenStack developer" identity is reinforced, at the expense of some awareness of the technical community in the greater OpenStack ecosystem. And now, with the main event over 5000 attendees, another inflection point has been reached, where in addition to per-project tracks at the developer summit, specific projects are co-ordinating smaller "mid-stream" events to encourage the creation of an even tighter per-project active participant identity. Beginning next year, the developer event will be held completely separately, which will help to reinforce the "OpenStack developer" identity by making that event smaller.Once again those numbers—150, 500, 1500, 5000 - Dunbar's inflection points—match quite nicely to the moment where the communities feel an unease with the state of affairs, and start to look for ways to scale further.

Loss of Voice

Christopher Alexander et al describe the "Community of 7000" (close enough to Dunbar's 5000) in A Pattern Language, a 1970s architecture book (part of the Portland Experiment series—hat-tip to Federico Mena Quintero for introducing me both to this and to Jane Jacobs' theories on the evolution of healthy communities). His characterization of this, which matches both Dunbar's group of 5000 (and coincidentally Plato's theoretical optimal size of a democracy, 5040), is that it is also approximately the size of a group where an individual feels that they have no say in the affairs of the group. It is also the size at which town meetings in Massachusetts can move from "open to all" to representative meetings, open only to elected representatives (6000 residents). And it is also a size at which companies tend to hit scaling challenges both in terms of revenue, cost of innovation, and general employee satisfaction (moving from "feeling like part of a family" to "feeling like a cog in a machine"). Geoff West has described (article) how companies (TED video) act like organisms—as they get bigger, their growth slows, and become dominated not by innovation, but by economies of scale. There are a multitude of articles describing the periods of growth, with periodical moments of crisis, in the growth of articles (here's one and one more). I contend that open source projects that stay centrally organized act more like companies, and those who achieve hyperdecentralization (what Ori Brafman describes as a "starfish" organization in The Starfish and the Spider) act more like ecosystems like forests and cities.


What does this all mean? It means that communities evolve and mutate as they grow. The minimum viable infrastructure for a small three-developer project is not the same as for a huge ecosystem like OpenStack. There will be moments of growth punctuated by moments of unrest—and at those moments, change is needed to allow growth to continue, or the community will stagnate and die. Those changes will occur around the boundaries of Dunbar's numbers. With each change, something of what went before will be lost, causing nostalgia, anxiety, and some discontent that things were better before. Good communities will pay attention to these emotional consequences too. Perpetuating the founding values of a community as it scales is a challenge, and as a community grows a mix of dogma, lore, and stories can be used to pass on values. It means that as communities grow, group identity, and the sub-groups that grow from group identity, needs to be managed—to avoid the anti-patterns of the clique, the water cooler, or corporate command and control. Applying consistent community values will help avoid such anti-patterns.