A new study offers a rather stark picture of how long-term friendships work: While we might not stay friends with the same people throughout our lives, we do tend to maintain the same number of friends, researchers say. In other words, "our capacity for maintaining emotionally close relationships is finite," says an Oxford expert in a press release on the study. "New friendships come at the expense of 'relegating' existing friends." The study involved following a group of 24 students in a British city over 18 months, by which time 10 of them left their hometown for college, Science reports.
The subjects began the study by assigning their friends, relatives, and acquaintances each a "closeness" score indicating level of intimacy. The students filled out the survey three times over the 18 months. Meanwhile, each received a cell phone, and researchers kept track of who the subjects called and how long they spoke to the person; "closeness" ratings tended to match phone-call frequency and duration fairly well. Researchers found that the number of people called and the amount of time spent on those calls stayed about the same—even as the identities of those people changed. Click for more on the study.