Primates frequently form affiliative relationships that have important fitness consequences. Affiliative relationships between unrelated males and females are ubiquitous in humans but are not widely reported in humans' closest living relatives, chimpanzees (Pan troglodytes). Instead, adult male chimpanzees are extremely aggressive to females, using the aggression to coerce females to mate with them. Adolescent male chimpanzees are physically and socially immature and unable to use aggression toward females in the same way as adult males. Instead, adolescent males might build affiliative relationships with females as an alternative tactic to increase their chances of mating and reproducing. To investigate this possibility, we recorded social interactions between 20 adolescent and 10 young adult males and 78 adult female chimpanzees over 2 years at Ngogo in Kibale National Park, Uganda. Analyses using grooming and proximity as assays revealed that adolescent and young adult males formed differentiated, affiliative relationships with females. These relationships were as strong as the bonds young males formed with maternal kin and unrelated males and increased in strength and number as males aged and started to dominate females. Male-female relationships extended outside the immediate context of mating. Although males affiliated slightly more often with females when they were cycling, they also did so when females were pregnant and nursing young infants. Males and females who formed bonds reassured each other, looked back and waited for each other while traveling, and groomed more equitably than other male-female pairs, even after the time they spent together in association and the female's reproductive state were taken into account. Despite the affiliative nature of these relationships, adolescent and young adult males selectively targeted their female partners for aggression. These findings provide new insights into the evolution of social bonds between human females and males, which can involve both affiliation and coercive violence.

中文翻译：

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青春期和年轻的成年雄性黑猩猩与雌性黑猩猩形成亲和但具有攻击性的关系。

灵长类动物经常形成具有重要健康后果的从属关系。无关的雄性和雌性之间的亲缘关系在人类中无处不在，但在人类最亲近的亲戚黑猩猩（Pan troglodytes）中却没有广泛报道。相反，成年雄性黑猩猩对雌性极具攻击性，利用这种攻击性迫使雌性与它们交配。青春期雄性黑猩猩在身体和社交上都不成熟，无法像成年雄性一样对雌性使用攻击性。相反，青春期男性可能会与女性建立从属关系，作为增加交配和繁殖机会的替代策略。为了调查这种可能性，我们在乌干达基巴莱国家公园的 Ngogo 记录了 20 只青春期和 10 只年轻成年雄性黑猩猩和 78 只成年雌性黑猩猩之间 2 年的社交互动。使用修饰和接近度作为分析的分析表明，青春期和年轻的成年男性与女性形成了差异化的从属关系。这些关系与年轻男性与母系亲属和无关男性形成的纽带一样牢固，并且随着男性年龄的增长并开始支配女性而在强度和数量上增加。男女关系扩展到交配的直接背景之外。尽管男性在骑自行车时与女性的联系稍微多一些，但在女性怀孕和哺乳婴儿时他们也会这样做。结成羁绊的男女在旅途中互相安慰，回首等待，并且比其他男女配对更公平地梳理，即使在他们一起度过的时间和女性的生殖状态被考虑在内之后也是如此。尽管这些关系具有亲和性，但青春期和年轻的成年男性有选择地将其女性伴侣作为攻击目标。这些发现为人类女性和男性之间社会纽带的演变提供了新的见解，这可能涉及从属关系和强制暴力。