Kordon Stephanie, Webb Christine E, Brooker Jake S, de Waal Frans B M, Clay Zanna
Department of Psychology, Durham University, South Road, Durham DH1 3LE, UK.
Department of Human Evolutionary Biology, Harvard University, Divinity Avenue, Cambridge, MA 02138, USA.
R Soc Open Sci. 2024 Dec 18;11(12):240435. doi: 10.1098/rsos.240435. eCollection 2024 Dec.
Early maternal loss can have lasting detrimental effects on primate social development. While many rehabilitation settings provide enriching environments to buffer against such effects in orphans, previous research indicates that young bonobo () orphans exhibit striking deficiencies in socio-emotional competence compared to their mother-reared peers. However, such studies are generally cross-sectional, without accounting for changes across the lifespan. We conducted longitudinal observations in bonobos living in an accredited African ape sanctuary to examine how rearing background, sex and age predict social tendencies including affiliation, consolation and aggression risk. Affiliative tendencies increased in females and decreased in males with age but were overall lower in orphans compared to mother-reared bonobos. Consolation tendencies decreased with age in mother-reared bonobos, while orphans showed consistently lower consolation (akin to levels of older mother-reared individuals). Young and male bonobos were more likely to receive aggression, while mother-reared and older females were more likely aggressors. Our study highlights the potential that ape sanctuaries like this can have by demonstrating that orphans exhibit decreased affiliative tendencies yet show social functioning ranging within patterns of their mother-reared peers. We discuss these results in the context of bonobos' natural social ecology and ongoing rehabilitation efforts in this species.
早期母源丧失会对灵长类动物的社会发展产生持久的不利影响。虽然许多康复环境提供了丰富的环境来缓冲孤儿所受的此类影响，但先前的研究表明，与由母亲抚养的同龄倭黑猩猩相比，幼年倭黑猩猩孤儿在社会情感能力方面存在明显缺陷。然而，此类研究通常为横断面研究，未考虑整个生命周期内的变化。我们对生活在一家经认证的非洲猿类保护区的倭黑猩猩进行了纵向观察，以研究抚养背景、性别和年龄如何预测社交倾向，包括亲密关系、安慰行为和攻击风险。随着年龄增长，雌性的亲密关系倾向增加，雄性则减少，但与由母亲抚养的倭黑猩猩相比，孤儿的亲密关系总体较低。在由母亲抚养的倭黑猩猩中，安慰行为倾向随年龄增长而减少，而孤儿的安慰行为始终较低（类似于年龄较大的由母亲抚养的个体的水平）。幼年和雄性倭黑猩猩更有可能受到攻击，而由母亲抚养的和年龄较大的雌性更有可能成为攻击者。我们的研究通过表明孤儿的亲密关系倾向降低，但在其由母亲抚养的同龄人的模式范围内表现出社会功能，凸显了这样的猿类保护区可能具有的潜力。我们在倭黑猩猩的自然社会生态和该物种正在进行的康复努力的背景下讨论了这些结果。
