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Friday, January 2, 2015

Dunbar's Number—and YOU! (Part 1 of 2)

Last month I sat looking at my Christmas card list and realized that eight people I knew died last year—seven within the last five months. Two were young. That rattled me. It got me thinking about a concept my friend Ed introduced me to: Dunbar’s Number. Robin Dunbar is a British anthropologist who studies societies and human beings’ interactions within their tribes. Dunbar studies contemporary cultures and his findings apply to many of us living today, whether we live in crowded cities, small villages or in the middle of nowhere.

I’ll write from my perspective as a 41-year-old woman living in an American suburb in 2015. When I write about American life and perspectives it’s because I live here. I don’t speak for all Americans nor do I intend to imply that America is the center of the universe or the only good place to live. But it’s what I know so I see the world through that lens.

Backing up to Dunbar’s use of the word “tribe.” When I hear that word I think of times past, when people literally lived with a certain group, sometimes nomadically. Everything they needed was hunted, gathered or made by the tribe. Life was communal. “Tribe” connotes a group that needs to stick together for safety and survival. Outsiders were looked on suspiciously as a potential threat to the tribe’s wellbeing. Tribes did not email other tribes on the other side of the world.

In 2015 in America we may not see ourselves as living in tribes. (Of course, there are groups who live separately even if they live in relatively close proximity to others. The Amish come to mind. I’m intrigued by them. More on that—someday.) But perhaps our connections to others really are the descendants of tribal connections. The tribe is less homogenous than it once was, but maybe we’re still tribal after all. In today’s society, tribe doesn’t have the same meaning it once did. But Dunbar uses this term because it describes the concept of grouping, even if the groups aren’t physically close to one another.

Adjustments to my Christmas card list last month didn’t lead me to ponder tribes for the first time. I think of the concept of tribes quite a bit, actually. Every year I meet new people through my kids’ two schools. Friends and neighbors move away. Others move in. My circle of friends and family members changes yearly. I feel overwhelmed as I think of all the people I’d like to see or catch up with. But I still only have 24 hours in a day. I must take inventory periodically and decide which connections I will prioritize.  

Dunbar has found that the average number of people one can maintain a real connection to is 150. He backs this number up in various ways. Dunbar studied tribe size and behavior but also takes a look a scientific measurements such as neocortex size.

After a while the scientific stuff starts ricocheting around in my brain like a pink pong ball on Red Bull.  I’m mean, how often in daily speech am I using the word “neocortex?” Not very often, especially on weekends! But I relate to the point Dunbar was making. Even if Dunbar’s analysis did not include a scientific look at brain size, I still would see his points as valid based on social behavior alone. We humans can’t maintain an infinite number of relationships. Relationships take time and energy and a true mutual interest if they are to grow and do well. You can’t have 5,000 real friends. (Yes, this is a jab at Facebook! Why do they limit it to 5,000? Is that a reasonable limit, in their eyes? 5,100 would be preposterous but 5,000 is completely manageable?! I am not a Facebook user. I did try it once, years ago, in order to read a writer friend’s work, which was posted there. But I don’t like how it shoves people at you and compares notes on how many friends all the other people have. So junior-high-ish! At times I’ve felt ignored by those I thought were real friends because they were so busy with their Facebook friends (people they never saw or talked to by phone), doing important things like comparing sock color. I was bothered that people I liked spent so much time doing online debates with acquaintances or friends of friends rather than connecting with true, living, breathing people they knew. I felt dumped for Facebook!)

As much as I’d love to be in touch with people I knew from other chapters of my life, it does get harder with each passing year. Maybe it’s the phase I’m in, because my kids are in elementary school. I’m still arranging play dates and I know who their classmates are. My time is spent helping them form connections. This will be different when they are in high school. For now, my time is closely bound to their world. I can’t cram 20 phone calls and 80 emails into the hours when they are in school. So I must pick and choose.

This discussion can end here if you like. I’ve made all the points I wanted to make. I find this stuff fascinating. I’m always curious about what we do and why. If you’re interested in more about Dunbar’s Number, check him out on Wikipedia or read here:


Dunbar's number is a suggested cognitive limit to the number of people with whom one can maintain stable social relationships. These are relationships in which an individual knows who each person is, and how each person relates to every other person.[1] Proponents assert that numbers larger than this generally require more restrictive rules, laws, and enforced norms to maintain a stable, cohesive group. It has been proposed to lie between 100 and 230, with a commonly used value of 150…Dunbar's number was first proposed by British anthropologist Robin Dunbar, who theorized that "this limit is a direct function of relative neocortex size, and that this in turn limits group size ... the limit imposed by neocortical processing capacity.

In a 1992 article, Dunbar used (neocortex size in) non-human primates to predict a social group size for humans. Dunbar formed his predictions about human tribe size using average neocortex size that developed approximately 250,000 years ago, during the Pleistocene age…Dunbar searched the anthropological and ethnographical literature for census-like group size information for various hunter–gatherer societies, the closest existing approximations to how anthropology reconstructs the Pleistocene societies.

Dunbar's surveys of village and tribe sizes also appeared to approximate this predicted value, including 150 as the estimated size of a Neolithic farming village; 150 as the splitting point of Hutterite settlements; 200 as the upper bound on the number of academics in a discipline's sub-specialization; 150 as the basic unit size of professional armies in Roman antiquity and in modern times since the 16th century; and notions of appropriate company size.

Dunbar has argued that 150 would be the mean group size only for communities with a very high incentive to remain together. For a group of this size to remain cohesive, Dunbar speculated that as much as 42% of the group's time would have to be devoted to social grooming. Correspondingly, only groups under intense survival pressure,[citation needed] such as subsistence villages, nomadic tribes, and historical military groupings, have, on average, achieved the 150-member mark. Moreover, Dunbar noted that such groups are almost always physically close: "... we might expect the upper limit on group size to depend on the degree of social dispersal. In dispersed societies, individuals will meet less often and will thus be less familiar with each, so group sizes should be smaller in consequence." Thus, the 150-member group would occur only because of absolute necessity—due to intense environmental and economic pressures.

Dunbar, in Grooming, Gossip, and the Evolution of Language, proposes furthermore that language may have arisen as a "cheap" means of social grooming, allowing early humans to efficiently maintain social cohesion. Without language, Dunbar speculates, humans would have to expend nearly half their time on social grooming, which would have made productive, cooperative effort nearly impossible. Language may have allowed societies to remain cohesive, while reducing the need for physical and social intimacy.[6]

Dunbar's number has since become of interest in anthropology, evolutionary psychology,[7] statistics, and business management. For example, developers of social software are interested in it, as they need to know the size of social networks their software needs to take into account; and in the modern military, operational psychologists seek such data to support or refute policies related to maintaining or improving unit cohesion and morale.

A recent study has suggested that Dunbar's number is applicable to online social networks as well.[8][9] Whether online interactions count as stable social relationships is debatable, as virtual engagements do not stimulate the same biological responses real interactions do.[10]

Alternative numbers

Anthropologist H. Russell Bernard and Peter Killworth and associates have done a variety of field studies in the United States that came up with an estimated median number of ties as 231.”  

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