Dunbar's Number
It’s time to turn down the heat. We desperately need to hone the well-known strategies needed to maintain stable Dunbar-size groups.
Though I am now retired, I enjoyed a nearly 50-year career as an engineer. As you might expect, numbers have occupied a significant portion of my brain’s landscape. For those of us with brains so-inclined, numbers provide an important lens through which we experience the world.
I’ve been thinking a lot about numbers lately. I’m not quite sure why. But I’ve learned through my 70+ years roaming the earth that I should pay attention to echoes from my psyche. I may have more to say about other significant number in future posts. But for now, my mind has turned to Dunbar’s Number.
Dunbar first proposed his number in the 1990s based on a correlation between the average brain size of different primate species and the average size of their corresponding social group. Using the average brain size of Homo Sapiens (us), Dunbar suggested that we can comfortably maintain stable relationships in a group of up to 150 people.
Dunbar explained the principle informally as "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."
I’ve always used two guideposts to assess important numbers.
A number’s value should be scrutinized for reasonableness by alternative means.
One should not get too hung up on the exactness of a number’s value. For most things, one and half significant figures is about as good as it gets.
Many researchers have questioned Dunbar’s conclusions or the value of his number. But in my mind, there is substantial evidence that a socially stable group is somewhere in the vicinity of 150 people. It seems fairly obvious to me that my ability to interact with all or most of the members of my tribe would be restricted by what information my brain could hold … and 150 feels somehow about right, give or take. Additionally:
Archaeological evidence suggests that “prehistoric hunter-gatherers lived in groups that consisted of several families resulting in a size of a few dozen people.”
Dunbar’s Number
The US Department of Defense says that a company is “a tactical-sized unit that can perform a battlefield function on its own” and “has anywhere from a few dozen to 200 soldiers.”
Dunbar’s Number
Given that the size of Dunbar groups depends on brain size, modern social structures (e.g., work groups, clubs, churches) would also seem to be limited to some maximum number of members in order for it to remain stable without the imposition of overly restrictive rules or laws.
A recent article in The Atlantic magazine (The Anti-Social Century by Derek Thompson), paints a disturbing trend in the decline of time we spend in-person socializing. Yes, we’re doing a lot of online interacting. But is this really the same as maintaining relationships through in-person social interactions? I suspect not. In his book Bowling Alone, Robert Putnam suggests that the decline in community engagement (particularly those that fostered face-to-face involvement) has had a negative impact on such things as voter turnout and trust in government. Putnam notes that these trends began in the 1950s.
Though the trends noted by Thompson and Putnam pre-date social media, the advent of this form of interaction doesn’t seem to have lived up to its community-building promise. Unlike the number of members in face-to-face groups (which have physical constraints) the number of members of online groups can, for all practical purposes, be infinite for all practical purposes. And unlike face-to-face organizations, moving into and out of online groups can be done in seconds. Unlike in online groups, anonymous interactions are impossible when face-to-face.
Perhaps our failure to personally engage in social structures of something like the Dunbar Number size is making it difficult for us to get along at the 335-million-member level as well. Relationships within Dunbar groups require such things as navigating personal differences, figuring out how to maintain group cohesion, and learning to work together.
Relationships at the 335-million-member level are obviously much more complicated. Yes, they must necessarily be subjected to rules, laws, and norms. But the attitudes and strategies required in Dunbar groups are the same attitudes and strategies needed at the 335-million-member level. We still need to navigate personal differences, figure out how to maintain group cohesion, and learn to work together.
Many of us are exasperated by the political dysfunction of our elected representative bodies. Some apparent dysfunction should be ignored, as it’s the inevitable byproduct of a large vibrant country with many competing interests and policy ideas. We should tolerate a certain level of chaos. That said, though, I think most of us would agree that we’re well beyond an acceptable level of tolerable chaos.
The US Senate does at least marginally better than the House of Representatives. One reason, of course, is that US Senators serve rotating six-year terms, as opposed to concurrent two-year terms for Representatives. Senators also represent larger and more politically diverse regions than Representatives, who are increasingly elected from highly gerrymandered districts.
We should also note that the US Senate is much smaller – 100 members (below the Dunbar Number) vs. 435 in the House (well above the Dunbar Number). The brain sizes of Senators (though seeming to be at the smaller end of the Homo Sapien brain-size distribution) should enable the Senate to more easily operate as a stable group.
The Dunbar Number problem is resolved in large representative bodies by political parties. Intra-party struggles, negotiations, and compromises take place much as they would in a hunter-gatherer tribe … without significant application of rules or laws. There are clearly incentives for maintaining a level of group stability.
When parties have a large diversity of policy preferences, smaller caucuses can come and go as a means for working out differences so that laws may be made. At the party and caucus level, the Homo Sapien brain can navigate interactions, make compromises, and successfully engage in the necessary give-and-take. At 435 members (capped by an act of Congress in 1921), the US House of Representatives might not be able to operate at all without political parties.
In his book Breaking the Two-Party Doom Loop: The Case for Multiparty Democracy in America, Lee Drutman suggests that up until fairly recently, our two-party system was actually four parties – liberal and conservative Democrats and liberal and conservative Republicans. Drutman shows that starting roughly 1960 (see chart below), the two wings of each major party began to coalesce, culminating in total collapse around 1990. This process can also be seen in the decline of moderate representatives, i.e., those that regularly voted differently than either liberal Democrats or conservative Republicans. Increasing use of the filibuster in the Senate, something rarely used prior to 1960, is further evidence of our unstable polarized governing bodies.
Each major party now has over 200 members of the SAME tribe in the House. We might wonder whether some of the all-too-public intraparty feuds and general political dysfunction are due to Dunbar-Number-stressed political groupings now that the parties are far less politically diverse.
In such an environment, most political systems might spawn alternative parties. In a similar period of political upheaval – i.e., in the runup to the Civil War – we saw the Republican party replace the Whigs. Unfortunately, we have a political system that Duverger’s Law suggests will remain dominated by two major parties. The Republican party that emerged just before the Civil War did not add to the political landscape but rather replaced one of the existing two parties.
I’ve long been an advocate of increasing the number of viable political parties. Given the 50/50 nature of our current two-party politics, a minor party with as few as 10% of the representatives could wield amazing power – a power that was once wielded by elected moderates in the major parties. But upstart political parties not only run up against Duverger’s Law, but also an increasingly gerrymandered segmentation of the electorate as well as restrictive state ballot access statutes.
I’m not sure what can be done about the dysfunctional trend we find ourselves in. Leave your ideas in the comments. Here’s a few of mine … unlikely, but they only require action at the state level (and no constitutional amendments).
Implement independent redistricting commissions to reduce the impact of gerrymandering.
Remove restrictive state ballot access statutes to better allow minor parties to make their case to the electorate.
Replace state winner-take-all electoral college voting with selection by congressional district (as do Maine and Nebraska).
It may be time to turn down the heat and focus on our Dunbar relationships. We desperately need those strategies for their maintenance and stability.
Happy Valentine’s Day.
I almost added a ppg to the piece about Dunbar's Number declining with age. :)
My neocortex has got to be much smaller than Dunbar’s hypothetical size - I have a hard time remembering the names of our 10 grandchildren!