This theory provides the perfect excuse not to befriend coworkers

An anthropological brain theory could be the driving force behind why you shouldn’t be friends with your coworkers — you need to save room in your brain.

The idea is that the more space you allow for useless relationships — like those with distant coworkers — the less room your brain has to remember meaningful, important things on a consistent basis.

Once the human brain makes its’ acquaintance with 100 to 150 people, it loses the ability to recall information like who owes them a favor or who organizes the office potlucks.

Explaining “Dunbar’s number”

Robin Dunbar, an anthropologist, penned the theory of “Dunbar’s number” in the 1990s. Since then, he’s written dozens of follow-up articles, in which he determined that in the days of cavemen and tribes, human beings had a certain limit on how many faces, names, and emotional connections they could establish.

Using the “social brain hypothesis,” Dunbar notes that the human (or in some cases, primate) brain’s volume has evolved to contain neural space for relationships, whereas other animals haven’t necessarily evolved in that capacity. That said, the brain does have its limits.

He asserts that in order to maintain stable, comfortable relationships, human beings can’t handle more than 15 really good friends at one time – those you’d be intimately close with. That number then extends to 50-100 people that you’re somewhat friendly with, and 150 who you can remember.

Beyond that, you’ll start forgetting key information about those around you unless there’s a hierarchical structure in place that mentally primes you. In general, you’ll remember the faces of about 1,500 people as well, but Dunbar posits that this is the extent of the brain’s social abilities.

Dunbar also suggests that humans tend to “spontaneously” team up to make groups along small, odd numbers, like 3–5 or 9–15.

An article on the research of social contact zeroed in on Dunbar’s number, and found that in a study on the exchange of Christmas cards, the average person’s maximum total network size was 153 people — or 153 cards sent out that year. The mean network size of people actually contacted was only 125, and 21% of recipients were found to be family members. Related factors include how often they contacted the individuals they were sending the cards to, physical distance from the recipient, emotional distance, and the frequency with which they communicated.

Is it outdated?

The research up until this point seems compelling, both from an anthropological and a psychological standpoint. Some argue that in the age of social media and the internet, Dunbar’s number is archaic and essentially obsolete.

These researchers argue that the human brain evolves and develops as culture changes. With the advent of the internet, people are exposed to more names and faces than we ever have been, and those who you would normally forget after years of absence are now Facebook friends —and you see pictures of them nearly every day.

There’s a chance that the human brain has now begun to rapidly evolve in a way that accommodates for this new surge in social contact. And the fluidity of weaker relationships turning into stronger ones — with just one click on a friend request button — shows that we’ve evolved far beyond cavemen and into the modern era.

Robin Dunbar, however, argues that his theory stands the test of time against the naysayers. “More than a dozen neuroimaging studies have shown that, in both humans and monkeys, the size of an individual’s social network correlates with the size of their default mode neural network,” Dunbar states in an article he wrote for The Conversation. This means that when one is at rest, in the unconscious processes of the mind, one’s ability to recall names and faces corresponds to the size of their amygdala, which corresponds to memory, emotions, and decision-making.

Does it work?

Though some may not be convinced of the theory’s longevity, others swear by it and are even a bit superstitious about it. Having too many friends that are coworkers may distract from one’s work, or worse, cause one’s brain to get overwhelmed by all the names, faces, and associated facts — especially if there are over 150 people at your company.

Everyone who’s ever worked at a startup knows all about the “150 employee rule,” which is the unspoken effect of obtaining more than 150 staff members. Some say communication and bonding between teams break down, the informal hierarchy turns into a complicated and elusive set of social rules that create tension, and company goals at large may even become less straightforward.

Startups aren’t the only organization wary of the “150 employee” rule’s impact. In 2007, the Swedish Tax Authority literally restructured their entire office around Dunbar’s research. They took their 1,350 employees and restructured them into units of 150, splitting them up into various offices to increase their productivity and efficiency.

Sweden reports a generally high level of satisfaction with their municipal governmental services, so perhaps they’re onto something.