September 23, 2023

LONDON – How many friends can a person have?

In a 1993 study, Robin Dunbar, a British anthropologist, theorized that humans could have no more than 150 meaningful relationships, a measure known as Dunbar’s Number.

But Stockholm University researchers published an article last week questioning that number. They found that if they tried hard, people could have far more friends.

“We can learn thousands of digits from pi, and if we deal with many people, we will be better able to relate to many people,” said Johan Lind, author of the study and associate professor at Stockholm University. The paper was published in the journal Biology Letters.

In his original research, Dr. Dunbar Monkeys and Monkeys and found that the size of the neocortex, the part of the brain responsible for conscious thinking, correlated with the size of the groups in which they lived. The neocortex in humans is even larger, so he extrapolated that their ideal group size averaged 150.

In the new study, Dr. Lind said he and his team used updated datasets and statistical methods, and found that the size of the neocortex did not limit the number of connections people could maintain. Dunbar’s number, he said, “has been criticized for a long time.” Dr. Lind’s team found that no maximum number of friendships could be made with any precision.

In an interview, Dr. Dunbar, Professor of Evolutionary Psychology at Oxford University, reported on his research. The new analysis, he said, “is insane, absolutely insane,” adding that Stockholm University researchers performed a flawed statistical analysis and misunderstood both the nuances of its analyzes and the human connections. “I am amazed at your apparent lack of understanding of relationships.”

Dr. Dunbar defines meaningful relationships as those people you know well enough to greet them without feeling uncomfortable when you run into them in an airport lounge. That number usually ranges from 100 to 250, with an average around 150, he said.

At birth, it starts with one or two. Friendships peak in their late teens and early 20s. By age 30, people typically have around 150 connections, and that number will stay the same until people reach their late 60s and early 70s when their connections count, according to Dr. Dunbar, “begins to sink”. “If you live long enough, it will come back to one or two.”

In his book “How Many Friends Does a Person Need?” Dunbar used historical and modern examples to support his research. Around 6000 BC Neolithic Middle Eastern villages were 120 to 150 people, measured by the number of dwellings. In 1086, the average size of most of the English villages recorded in the Domesday Book was 160 people. In modern armies, combat units have an average of 130 to 150 people, he said.

In 2007, when the Swedish Tax Service was restructuring, a strategist from the agency suggested that each of the new offices should employ between 100 and 150 people, citing Dr. Dunbar’s research results. Employees who were already dissatisfied with the restructuring got wind of the plan and complained about being compared to monkeys. (Dunbar’s number ultimately didn’t play a role in the agency’s restructuring, according to three officials involved in the plans.)

While it may be comforting to believe that there are an optimal number of people we should surround ourselves with, in reality there isn’t a single rule that applies to all of us, said Louise Barrett, professor of psychology at Lethbridge University in Canada . “Human life is really complicated,” she said.

Dr. Barrett, a biological anthropologist who was not involved in the new study and previously worked for Dr. Dunbar had studied said the analysis was robust. “We need to rethink and adjust our interpretation and hypotheses in light of this new data,” she said.

The relationship debate comes because people are rethinking what friendships they want to rebuild after the pandemic, and companies are designing work spaces after the pandemic.

Recognition…Colin McPherson / Corbis via Getty Images

Dr. Dunbar proposed his theory decades ago, in the early days of the internet and long before social media sites changed the way people communicate. “That number would make sense if we were still relying on a Rolodex and talking to people, but that’s not the world we live in,” said Angela Lee, professor at Columbia Business School.

Networking tools like LinkedIn have made it possible to increase the number of connections we can maintain. This is important because research shows that people on the outer fringes of our networks are often most helpful in advancing their careers or generating creative ideas, she said.

Dr. Dunbar claimed that his theory is still viable in today’s hyper-connected world, as the quality of connections in social networks is often poor. “These are not personalized relationships,” he said.

What does the pandemic mean for rebuilding meaningful connections, be it at work or in our social lives? It’s probably too early to tell, but Dr. Dunbar predicted that the biggest impact on networks would be older people. “Their friendship circles were already falling and this will drive them further down the slope,” he said.

Dr. Dunbar said that while trying not to analyze himself, he estimated that he had about 150 friends.

“It’s pretty obvious to most people when they sit down and think about that their social network is that organized,” he said. Dunbar’s number, he said, isn’t going anywhere.