How Large Is Your Network? What Does Dunbar’s Number Really Mean?

Dunbar’s Number is one of the most misunderstood concepts in sociology. We address it somewhat quickly in The Start-Up of You. In Reid’s latest LinkedIn post, we explain the nuance behind limits to the number of people in your network:

Imagine you receive a digital camera with a built-in memory card for your birthday. You bring it on a six-month trip to Africa where you won’t have access to a computer—so all the photos you want to keep must fit on that one memory card. When you first arrive you snap photos freely, and maybe even record some short videos. But after a month or so, the memory card starts filling up. Now you’re forced to be more judicious in deciding how to use that storage. You might take fewer pictures. You might decide to reduce the quality/resolution of the photos you do take in order to fit more. You’ll probably cut back on videos. Still, inevitably, you’ll hit capacity, at which point if you wish to take new photos you’ll have to delete old ones.

Just as a digital camera cannot store an infinite number of photos and videos, you cannot maintain an infinite number of relationships. Which is why, even if you are judicious about your choices, at some point you hit a limit, and any new relationship means sacrificing an old one.

The maximum number of relationships we can realistically manage—the number that can fit on the memory card, as it were—is described as Dunbar’s Number, after evolutionary psychologist Robin Dunbar. But maybe it shouldn’t be. In the early nineties, Dunbar studied the social connections within groups of monkeys and apes. He theorized that the maximum size of their overall social group was limited by the small size of their neocortex. It requires brainpower to socialize with other animals, so it follows that the smaller the primate’s brain, the less efficient it is at socializing, and the fewer other primates it can befriend. He then extrapolated that humans have an especially large neocortex and so should be able to more efficiently socialize with a great number of humans. Based on our neocortex size, Dunbar calculated that humans should be able to maintain relationships with no more than roughly 150 people at a time. To cross-check the theory, he studied anthropological field reports and other clues from villages and tribes in the hunter-gatherer era. Sure enough, he found the size of surviving tribes tended to be about 150. And when he observed modern human societies, he found that many businesses and military groups organize their people into cliques of about 150. To wit: Dunbar’s Number of 150.

But Dunbar’s research is not exactly about the total number of people that any one person can know. The research focused on how many nonhuman primates (and humans, but only by extrapolation) can survive together in a tribe. Of course, group limits and the number of people you can know are closely related concepts, especially if you consider everyone in your life to be part of your social group. Yet most of us define our total social group more broadly than Dunbar did in his research. Survival in the modern world doesn’t depend on having direct, face-to-face contact with everyone in our social network/group, as it did for the tribes he studied.

Regardless of how you parse Dunbar’s research, what is definitely the case is that there is a limit to the number of relationships you can maintain, if for no other reason than the fact that we have only twenty-four hours in each day. But, contrary to popular understanding of Dunbar’s Number, there is not one blunt limit. There are different limits for each type of relationship. Think back to the digital camera. You can either take low-resolution photographs and store one hundred photos in total, or you can take high-resolution photographs and store forty. With relationships, while you can only have a few close buddies you see every day, you can stay in touch with many distant friends if you only email them once or twice a year.

But there’s a twist. While the number of close allies and weak ties you can keep up is limited, those aren’t your only connections. You can actually maintain a much broader social network that exceeds the size of the memory card. It’s by smartly leveraging this extended network that you fully experience the power of I-to-the-We.

Your extended network are your 2nd and 3rd degree connections. Read the whole post for more.