Are you younger than 25 years old? You may want to appreciate this moment in life when your social circle is at its greatest. If you're older, you may relate to what you read next.
你现在不到25岁吗？你可能会想感谢生命中这个时刻，你的社交圈是最棒的。如果你年纪再大点，你可能会接触到你接下来将要读到的情况了。
Soon after your mid-20s, your social circle shrinks, according to a recent study by scientists from Aalto University in Finland and the University of Oxford in England.
根据来自芬兰阿尔托大学和英国牛津大学科学家的最新研究成果显示，20来岁后不久，你的社交圈会开始缩小。
The teams analyzed data from 3 million mobile phone users to identify the frequency and patterns of whom they contacted and when, as well as overall activity within their networks.
该团队分析了来自300万个手机用户的数据，以此判定他们联系的频率和模式，以及在网络上的整体活跃度。

Men and women were found to be socially promiscuous -- making more and more friends and social contacts -- until the age of 25, after which point they started losing them rapidly, with women losing them at an initially faster rate than men. The average 25-year-old woman contacts about 17.5 people per month, while a man contacts 19 people.
男性和女性在25岁之前不断交友，社交联系频繁，处于泛交状态。之后他们会开始迅速失去朋友，最初女性失去朋友的速度快于男性。25岁的女性每月联系17.5个人，而25岁的男性每月联系19个人。
This decline continues for the rest of your life, or at least until retirement.
在余生中，朋友的数量会继续下降，至少退休之前是这样的。
The theory is that around this age, people begin to decide who is most important -- and valuable -- in their life and make a greater effort to hold on to those friends.
在25岁这个阶段，人们开始决定人生中哪些人是最重要和最有价值的朋友，并且为了保住这些朋友付出更多努力。
"People become more focused on certain relationships and maintain those relationships," said Kunal Bhattacharya, a postdoctoral researcher at Aalto University who co-authored the study. "You have new family contacts developing, but your casual circle shrinks."
研究共同执笔人、阿尔托大学博士后昆瑙·巴塔查雅表示：“人们开始更注重并努力维系某些关系，建立了新的家庭关系，日常生活圈却缩小了。”
This applies to both partners and friends, and it stems largely from people wanting to settle down and raise a family.
这同时适用于伴侣和朋友，主要源自于人们想安定下来建立家庭。
"At the beginning of this age range, women are more focused," Bhattacharya said, meaning women are more intent on finding the correct partner. Once they believe they have, they invest more time in nurturing that relationship and lose others of less value.
巴塔查雅表示：“在这个年龄层初期，女性更加注重这方面”，意味女性更加倾向于寻找合适的伴侣。一旦认为找到了，就会投入更多时间培养这段关系，并舍弃其他较不具有价值的人。
"Once you've made decisions and found the appropriate people, you can be much less socially promiscuous and invest your time in these people," added Robin Dunbar, a professor of evolutionary psychology at the University of Oxford who co-authored the paper. "But they can't be just anybody," he added.
牛津大学进化心理学教授、该论文的共同作者罗宾·邓巴补充说道：“一旦你做出了决定并找到了合适的人，社交会更慎重，你会把时间投入到选择的人身上，而不是随意的任何人。”
Trends were seen to change slightly in people's late 30s: Men begin losing buddies at a faster rate. By the age of 39, the average man was contacting 12 people, while women were calling 15 people each month.
人们30岁以后，这一趋势看起来有轻微的改变：男性开始以更快的速度失去伙伴。到39岁时，男性平均每月联系12个人，而女性每月联系15个人。
Though the team emphasized that the rapid loss of friends happens in both men and women, experts generally consider this formation of an "inner circle" to be more important to women, mainly due to them having children.
尽管研究团队强调朋友快速流失同时出现在男性和女性身上，专家一般认为，“核心圈”模式对女性而言更重要，主要就是因为有了孩子。
"You make the effort in return for some benefits," said Dunbar, who believes that at this point, people will prioritize those who are more useful to them.
邓巴表示：“你会为了某些回报付出努力”。他认为，人们在这个阶段，会把“较有利用价值的人”放在优先位置。
At this point, contacts such as mothers, mothers-in-law, close friends and family come into play as they help people raise their children, known as the grandmother effect.
在这一阶段，与母亲、伴侣的母亲、亲近的朋友和家人连系，有助人们养育孩子，称作祖母效应。
"It's the 'tend and befriend' idea, meaning relationships become more important when you have children," said Michael Price, director of the Center for Culture and Evolution at Brunel University London who was not involved in the study. "You're now investing in offspring for the rest of your lives."
“这种'照料与结盟'理念，意味着当你有孩子以后关系会变得更加重要，” 并未参与这项研究的英国布鲁内尔大学文化演变中心主任麦克尔·普里斯说道，“你正在为你以后的生活投资后代。”
Price believes that men instead value more individualistic criteria, such as their achievements or status, once they have a family. "It's well established that close, personal relationships are more highly valued by women in general, while men value status more," he said.
普里斯认为，一旦男性拥有家庭后，会更加重视个体标准，如他们的成就或地位。他说：“经证实，通常来说女性更重视亲密私人的关系，而男性更重视社会地位。”