School of Psychology, University of St Andrews, Scotland, UK.
Dev Sci. 2011 Sep;14(5):1220-34. doi: 10.1111/j.1467-7687.2011.01069.x. Epub 2011 Jul 25.
Adult chimpanzees produce a unique vocal signal, the pant-grunt, when encountering higher-ranking group members. The behaviour is typically directed to a specific receiver and has thus been interpreted as a 'greeting' signal. The alpha male obtains a large share of these calls, followed by the other adult males of the group. In this study, we describe the development of pant-grunting behaviour from the first grunt-like calls of newborn babies to the fully developed pant-grunts in adults. Although babies produce grunts from very early on, they are not directed to others until about 2 months of age. Subsequently, socially directed grunting steadily increases in frequency to peak around 7 months of age, but then decreases again to reach a nadir in older infants and juveniles, while the specificity in use increases. During adolescence, grunt production increases again with grunts given most frequently to socially relevant individuals. As young chimpanzees are closely affiliated to their mothers for the first decade of their lives, we also compared the grunting patterns of mothers and their offspring, which revealed some influences in pant-grunt production. In conclusion, the acquisition of pant-grunting behaviour in chimpanzees is a long-lasting process with distinct developmental phases in which social influences by the mother and other group members are likely to play a role.
成年黑猩猩在遇到等级较高的群体成员时会发出独特的叫声——呼噜声。这种行为通常是针对特定的接收者的，因此被解释为“问候”信号。阿尔法雄性获得了大量的呼噜声，其次是群体中的其他成年雄性。在这项研究中，我们描述了从新生儿的第一声类似呼噜的叫声到成年黑猩猩完全发出呼噜声的呼噜声行为的发展过程。尽管婴儿很早就开始发出呼噜声，但直到大约 2 个月大时，他们才会将呼噜声指向其他人。随后，社交导向的呼噜声的频率稳步增加，在 7 个月大时达到峰值，但随后再次下降，在年龄较大的婴儿和青少年时降至最低点，而使用的特异性增加。在青春期，呼噜声的产生再次增加，最常向社交相关的个体发出呼噜声。由于年轻的黑猩猩在生命的头十年与母亲紧密联系，我们还比较了母亲和她们后代的呼噜声模式，这揭示了在呼噜声产生方面的一些影响。总之，黑猩猩呼噜声行为的习得是一个漫长的过程，具有明显的发育阶段，其中母亲和其他群体成员的社会影响可能发挥作用。
