Your brain has an exclusive VIP line for your friends.
And it only has room for a limited number of people. According to research just published in the Proceedings of the National Academy of Sciences, everyone has a finite number of close, personal friendships.
The number can be different for each person, but scientists found that once you reach your finite number of VIP friends, when you make a new one, your brain pushes one of the other ones out of the line. One in, one out.
The researchers say this may be due to schedule overload, emotional limits, or a combination of both factors.