Department of Psychology, University of Warwick, Coventry, UK.
School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK.
Nat Ecol Evol. 2022 May;6(5):644-652. doi: 10.1038/s41559-022-01689-z. Epub 2022 Mar 21.
In humans, individuals' social setting determines which and how language is acquired. Social seclusion experiments show that sociality also guides vocal development in songbirds and marmoset monkeys, but absence of similar great ape data has been interpreted as support to saltational notions for language origin, even if such laboratorial protocols are unethical with great apes. Here we characterize the repertoire entropy of orangutan individuals and show that in the wild, different degrees of sociality across populations are associated with different 'vocal personalities' in the form of distinct regimes of alarm call variants. In high-density populations, individuals are vocally more original and acoustically unpredictable but new call variants are short lived, whereas individuals in low-density populations are more conformative and acoustically consistent but also exhibit more complex call repertoires. Findings provide non-invasive evidence that sociality predicts vocal phenotype in a wild great ape. They prove false hypotheses that discredit great apes as having hardwired vocal development programmes and non-plastic vocal behaviour. Social settings mould vocal output in hominids besides humans.
在人类中，个体的社交环境决定了他们会学习哪种语言以及如何学习语言。社会隔离实验表明，社会性也指导着鸣禽和狨猴的发声发展，但由于缺乏类似的大型猿类数据，人们认为这支持了语言起源的跳跃式观点，尽管这种实验室方案对大型猿类来说是不道德的。在这里，我们描述了猩猩个体的发音曲目熵，并表明在野外，不同种群的社会程度与不同的“发声个性”有关，表现为不同的警报叫声变体的规则。在高密度的种群中，个体的发声更具原创性，声音也更不可预测，但新的叫声变体存在时间较短，而在低密度的种群中，个体更具从众性，声音也更一致，但叫声曲目也更复杂。这些发现提供了非侵入性的证据，证明社会性可以预测野生大型猿类的发声表型。它们证明了那些诋毁大型猿类具有固定的发声发展计划和不可塑的发声行为的错误假设是错误的。除了人类之外，社会环境还塑造了灵长类动物的发声输出。
