你需要多少個朋友？上課的時候有時候講到類似友誼的話題的時候會問下同學，是不是有交心的朋友的話題。其實不是調侃，是真的很好奇現在年輕人對于朋友的定義。How Many Friends Do You Really Need

關于朋友數量有個常被提到的數字是Dunbar 數字，來自于英國心理學家Robin Dunbar：人們能維系的關系數量上限是150（后面研究說可以更多）；親密關系的數量是5人。

The best-known theory of how many friends people can (though not necessarily should) have comes from British psychologist and anthropologist Robin Dunbar. What has come to be known as Dunbar’s number contends that humans are only cognitively able to maintain about 150 connections at once (subsequent research has put the number higher). That includes an inner circle of about five close friends, followed by larger concentric circles of more casual types of friends.

出于減少孤獨感的考慮，不管是朋友，還是家人，人至少需要一個交心的人。

If your goal is simply to mitigate the harmful impact loneliness can have on your health, what matters most is having at least one important person in your life — whether that’s a partner, a parent, a friend or someone else, said Jeffrey Hall, a professor of communication studies at the University of Kansas.

要從友誼里提高生活質量的，有研究說3個，也有說6個。

One 2016 study suggested people who have six or more friends have improved health throughout their lives, while a 2020 study by Suzanne Degges-White, professor and chair of the Counseling and Higher Education department at Northern Illinois University, found that middle-aged women who had three or more friends tended to have higher levels of overall life satisfaction.

當然到底需要幾位朋友，看個人的需求，如果你想體驗一些新的東西，那么交個朋友是比較合適的，只是要深交一位朋友，差不多需要200小時的投入。

Dr. Hall’s research suggests that on average, very close friendships tend to take around 200 hours to develop. Quantity and quality go hand-in-hand.