Much like a long-distance romance, it can be difficult to keep the spark alive in a friendship with someone living in a different city.

就像一段异地恋情一样，生活在不同城市的朋友间也很难保持友情的热度。

Now scientists say they have uncovered the key to staying close and it appears to be different for men and women.

现在科学家说，他们已经发现了保持亲密的诀窍—但这对于男人和女人来说似乎是不同的。

Men need to meet up face-to-face and bond over activities, according to the study of students leaving home for the first time, while for female friendships, long phone conversations can bridge the physical distance.

根据一项对初次离家的学生展开的调查，男人需要面对面的接触，并通过活动保持联系，而在女人的友谊中，煲电话粥也可以把距离拉近。

Professor Robin¹ Dunbar, who led the work at the University of Oxford², said: "What determined³ whether [friendships] survived with girls was whether they made effort to talk more to each other on the phone."

牛津大学领导该研究的罗宾•邓巴教授说：“女孩之间的友谊能否存续的决定因素在于她们是否努力在电话里聊得更多。”

However, talking had absolutely no effect on boys relationships, the study found.

然而，该研究发现，谈话对于男孩间的友谊没有丝毫作用。

"What held up their friendships was doing stuff together", said Dunbar.

“支撑他们友谊的是一起活动”，邓巴说：

"Going to a football match, going to the pub for a drink, playing five-a-side."

“比如一起去看足球赛、去酒吧喝酒以及踢五人足球。”

"They had to make the effort. "

“他们必须做出努力。”

"It was a very striking sex difference. " Should men invest more in friendships?

“这体现了惊人的性别差异。”男人应该在友谊里投入更多吗？

In the research, thirty students who were in their final year of sixth form were asked to compile detailed⁴ lists of all their friends and how close they felt to each of them.

在这项研究中，30名高中毕业生被要求详细列出所有的朋友以及与每个朋友间的亲密度。

Four months after the initial assessment⁵, the students took their final A-level exams and many left home for university.

在这次初期评估的四个月后，这些学生参加了A-level考试，当中许多人离开家上大学。

They were then followed up nine months and 18 months after the initial assessment.

研究人员分别在9个月后和18个月后对他们进行了跟踪研究。

Speaking to journalists at the annual meeting of the American Association for the Advancement⁶ of Science in Boston, Dunbar said different friendship styles between genders⁷ could be behind the effect.

在波士顿举行的美国科学促进会的年会上，邓巴对记者说道，男女对待友谊的不同方式是这种现象背后的原因。

"This is about the idea that women clearly have much more intense close friendships", he said.

“女人间的友谊显然更加紧密”，他说。

"They're very intense, very like romantic relationships in the sense if they break, they break catastrophically.

“这种关系非常紧密，非常像爱情—在这种强度下，如果关系破裂了，就是灾难性的。”

By contrast, men tend to have more casual friendships.

相比之下，男人间的关系往往更加随意。

"They tend to have a group of four guys that they do stuff with", he said.

“他们喜欢四个人凑在一起活动”，他说。

"With guys it is out of sight out of mind. "

“但不见面就忘了。”

"They just find four more guys to go drinking with. "

“他们只会另外找四个人一起去喝酒。”