It's bad news for Taylor Swift: a new report suggests that our brains can only handle being best friends with five best friends at a time.
Back in the '90s, anthropologist Robert Dunbar discovered a correlation between the size of a primate's brain and the size of their social group - the bigger the brain, the more friends they could have.
He went on to find that humans can only have a finite number of friends at once, due to the size of our neocortex (a part of the brain's cerebral cortex, concerned with sensory perception like sight and hearing). Our friend allowance is divided into four tiers of decreasing closeness, and works out at five best friends, ten close friends, 35 acquaintances and 100 'additional contacts' - you know, the ones you haven't seen for years but would still post a 'Happy Birthday' message on their Facebook wall...
As detailed in a new report in the MIT Technology Review, Dunbar then examined a massive six billion phone calls, made by 35 million people in an undisclosed European country (Genovia?) in 2007. The findings confirmed his previous theory, determining that most people have between 4.1 and 5 people that they talk to a lot.
The report stated that 'the team assumes that the frequency of calls between two individuals is a measure of the strength of their relationship. The average cumulative layer turns out to hold 4.1 [best friends], 11 [close friends], 29.8 [acquaintances] and 128.9 [additional contacts.]'
When it comes to friendship, then, it seems that it really is a case of quality over quantity, so you shouldn't feel too guilty next time you embark on a Facebook cull. Naturally, all of this leaves us wondering - which of Taylor's extensive squad will make it into the final five? Obviously, we're guessing that Selena Gomez and Ed Sheeran get a free pass into the 'best friends' circle, but who will take the other three slots? All of the Haim sisters? Two Victoria's Secret Angels and Lena Dunham? At least we can most likely rule Chloe Grace Moretz, Katy Perry and Kanye West out of the equation...
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