You might not have as many close friends as you think. Researchers have provided new evidence that lends weight to a theory that says you can only maintain five close friendships.

你的亲密朋友也许没有你想的那么多。研究员提供的新证据强调了一种观点，你只能维护好与5个人的亲密友谊。

You’ve probably heard of Dunbar’s Number which suggests that human beings can only maintain meaningful relationships with between 100 to 230 other people, and that number is typically 150. It’s been demonstrated to hold true in all kinds of situations—from ancient armies to big business.

你可能听说过邓巴数，它指出人只能与其他100~230个人维持有意义的人际关系，而且这个数字通常是150。从古代军队到财团，各种情况都证明它是有效的。

But you might not know that Robin¹ Dunbar, the anthropologist² behind the number, has since also suggested that those relationships are layered, like an onion. He argues that people typically have five ultra-close relationships, then 10 slightly less cozy companions, 35 at more distance, and then 100 in an outer circle. Now he and follow researchers have published data that appears to lend weight to the theory.

但是你也许不知道这个数字背后的人类学家罗宾·邓巴，他后来也指出，人际关系就像洋葱一样，是分层的。他表示人们通常有5个非常亲密的朋友，10个稍微不那么默契的朋友，35个有些距离的朋友，然后是100个自己圈子以外的朋友。如今他和追随他的研究员公布了那些看上去似乎强调了该观点的数据。

The remaining data was then clustered, to sort out whether there was layering in friendship closeness, where closeness was measured by the frequency of calls between two individuals. Turns out that the clusters shape up rather similarly to Dunbar’s suggestions, with 4.1 in the first layer, 6.9 in the next, then 18.8, and finally 99.1. The results are published on arXiv.

此外，剩余的数据是成串的，要整理出亲密友谊是否分层，而亲密度是通过衡量两个人之间通电话的频率来得出的。结果发现，这串数据发展成邓巴观点，更确切的说，与邓巴观点相似，4.1在第一层，6.9在下一层，然后再下一层是18.8，最后一层是99.1。这个研究结果被发表在arXiv上。