Campbell's Monkeys Use Affixation to Alter Call Meaning

Human language has evolved on a biological substrate with phylogenetic roots deep in the primate lineage. Here, we describe a functional analogy to a common morphological process in human speech, affixation, in the alarm calls of free-ranging adult Campbell's monkeys (Cercopithecus campbelli campbelli). We found that male alarm calls are composed of an acoustically variable stem, which can be followed by an acoustically invariable suffix. Using long-term observations and predator simulation experiments, we show that suffixation in this species functions to broaden the calls' meaning by transforming a highly specific eagle alarm to a general arboreal disturbance call or by transforming a highly specific leopard alarm call to a general alert call. We concluded that, when referring to specific external events, non-human primates can generate meaningful acoustic variation during call production that is functionally equivalent to suffixation in human language.

人类语言依托生物基础演化而来，其系统发育（phylogenetic）根源可追溯至灵长类演化支系的深处。本研究针对野外自由活动的成年坎贝尔猴（Cercopithecus campbelli campbelli）的报警叫声，阐述了其与人类语言中常见形态学过程——词缀构词法（affixation）——的功能类比。研究发现，雄性报警叫声由声学特征可变的词干构成，其后可接声学特征固定的后缀。通过长期野外观察与天敌模拟实验，我们证实该物种的后缀化发声功能在于拓展叫声的语义范畴：可将高度特异性的鹰类报警叫声转化为一般性的树栖惊扰叫声，或是将高度特异性的豹类报警叫声转化为一般性的警戒叫声。本研究得出结论：在指代特定外部事件时，非人灵长类可在叫声产生过程中生成具备语义意义的声学变异，其功能等价于人类语言中的后缀构词过程。