Obsession: Facebook 'friends' may total thousands but the human brain is only capable of keeping 150 friendships
The Facebook obsession of amassing 'friends' creates the impression that some users are wildly more sociable than others.
But while we may be able to count 5,000 friends on the online social networking site, scientists have shown that humans' brains are capable of managing a maximum of just 150 friendships.
Oxford University Professor Robin Dunbar has conducted a study of social groupings throughout the centuries, from neolithic villages to modern office environments.
His findings, based on his theory 'Dunbar's number', developed in the 1990s, asserts that size of the part of the brain used for conscious thought and language, the neocortex, limits us to managing 150 friends, no matter how sociable we are.
The professor of Evolutionary Anthropology has applied this theory to see if the 'Facebook effect'  has stretched the size of social groupings.
He compared the online 'traffic' of people with thousands and friends to those with hundreds.
His findings show that there is no discernible difference between the two.
'The interesting thing is that you can have 1,500 friends but when you actually look at traffic on sites, you see people maintain the same inner circle of around 150 people that we observe in the real world,' said Dunbar.
'People obviously like the kudos of having hundreds of friends but the reality is that they’re unlikely to be bigger than anyone else’s.'
Dunbar defined 'maintained' friends as those you care about and contact at least once a year.
He has also found that women are better at maintaining friendships on Facebook.
'There is a big sex difference though ... girls are much better at maintaining relationships just by talking to each other. Boys need to do physical stuff together,' he said.
Dunbar's findings, due to be published this year, will be welcomed by psychologists who warn that Facebook is driving a worrying trend of 'friendship addiction' causing insecurity in those who use it.
Addictions expert David Smallwood claims that many who use Facebook become hooked on the urge to acquire more friends in an attempt to appear popular and successful.