Research press release


Scientific Reports

Social evolution: Best friends aren’t forever

携帯電話の利用状況の大規模データベースを解析した結果を報告する論文が、Scientific Reportsに掲載される。この論文は、個々人の友人の好みについて、その男女差と一生にわたる変化の様子を明らかにしている。今回観察されたパターンは、男女の繁殖に対する投資戦略が一生の間にどのように変化するのかを反映しているのかもしれない。

R Dunbarたちは、19億5千万回の通話と4億8900万件の携帯メールのデータベースを解析して、親友についての好みと一生を通じた好みの変化を男女別に調べた。携帯電話での連絡頻度の高さをもとにして、各被験者の3人の最もお気に入りの友人を選び出し、この3人に焦点を当てて解析が進められた。「3人の最もお気に入りの友人」は、感情面での結びつきの優れた代理指標であることが、過去の研究で明らかになっている。


An analysis of a large database of mobile phone usage, published in the journal Scientific Reports, highlights the differences between the differences between the friendship preferences of men and women and how these choices change throughout our lifetime. The patterns observed may reflect the way the reproductive investment strategies of the two sexes change across lifespan.

Robin Dunbar and colleagues analyzed a database of 1.95 billion phone calls and 489 million text messages to study gender preferences in close friendships and how these preferences change throughout lifetime. They focused on each individual’s three most preferred friends, as indexed by the frequency of contact, which has previously been shown to be a good proxy for emotional closeness.

The authors found that young people tend to prefer their ‘best friend’ (the person with whom they are most frequently in contact) to be of the opposite gender and same age group — probably their spouse. From the age of about 50, a woman’s male best friend tends to move into second place, replaced by a younger female, potentially her daughter. Conversely, men are more likely to have a female best friend throughout their lives. The results indicate that women may be more focused on opposite-sex relationships during their reproductively active years, suggesting they invest more heavily in creating and maintaining pair bonds. As they age, women’s attention shifts from their spouse to younger females, assumed to be daughters, reflecting, perhaps, a shift in reproductive strategy from mate choice to personal reproduction to grandparental investment.

doi: 10.1038/srep00370


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