Humans Can Really Only Maintain Five Close Friends, According to This Equation

Choose wisely.  

5 MAY 2016

In an age of ubiquitous internet and a multitude of social media networks, it feels like we're capable of making hundreds upon hundreds of friendships - but new data from renowned British anthropologist Robin Dunbar says otherwise. According to a new report, despite our extremely connected lives, we're only able to maintain a mere five close friendships at a time. 

If you've not heard of Dunbar before, you might still be familiar with one of his theories: Dunbar's Number, which proposes that the average human being can only maintain 150 or so social friendships with any degree of stability. Now, he's back at it again to analyse just how many 'best' friends a typical individual can keep.


It makes sense that of these 150-ish friendships, some of those are closer than others. We don't, for example, pour out our innermost thoughts to all of those people, even if we're very friendly with them. According to Dunbar's research, these inner circles are about five people deep - a considerable drop from the small army we can maintain.

From this innermost circle of friends, the friendship limit gets larger and larger. The next circle of friends - people who you are pretty close with - averages to about 10 people. After that, an even less close group of about 35.

The final, and furthest away group comes in at 100, rounding out the list to 150, which is the maximum amount based on Dunbar's Number.

To come to this conclusion, Dunbar and a team of researchers looked at data gathered from 6 billion phone calls between 35 million people in an unnamed European country in 2007, Gizmodo's Jamie Condliffe reports. Clustering algorithms were used to spot patterns (in reciprocal calls that were returned, for example) and come up with the numbers for each social layer.

The two layers in the middle - the 10 and the 35 - was where most variation was found. This might suggest a difference between introverts and extroverts, suggest the researchers, or is perhaps a consequence of friendships changing over time.

The researchers tried to filter out business calls by eliminating calls that weren't returned regularly. They also ruled out individuals who didn't use their phones much, as presumably they interact with their social groups in other ways. (The most prolific caller, by the way, made an average of more than 40 calls over the course of each day - quite an achievement.)


The researchers also note that a person's social interactions typically involve more than just phone calls, so it's difficult to reach solid conclusions from this data alone.

That said, the data used in the study (from 2007) predates the original iPhone and the rapid rise of online social networks, so more recent influences and complications were discounted, because they weren't widely used.

"We find strong evidence for a layering structure," write the researchers in the paper published on pre-press website, arXiv.org. "However, finding discrete layers is still a considerable challenge... [the results] find a small number of clusters and show good support for the outer two layers."

Dunbar's research is continuing, and will now need to undergo the peer-review process, so until then, we'll have to take these findings with a grain of salt. But if you're thinking of adding a new best buddy to your group, you might want to consider distancing yourself from someone else first.

More From ScienceAlert

This powerful new painkiller could be the unexpected ticket to replacing opioids
16 hours ago
Hardcore eclipse chasers spend big money to watch the totality longer than everybody else

"Seeing the corona during totality is better than sex," says one of them.

16 hours ago