 Cheney and Seyfarth (2005) emphasize that non-human primates have a small, stimulus specific repertoire of vocal productions that are not “entirely involuntary,” and this contrasts with their “almost openended ability to learn novel sound-meaning pairs” (p. 149). They also emphasize that vocalizations in monkeys and apes are used to communicate information about the vocalizer, not to provide information intended to “rectify false beliefs in others or instruct others” (p. 150). Non-human primate communication consists in the mainly involuntary broadcasting of the vocalizer’s current affective state. Moreover, although Cheney and Seyfarth recognize that the vervet monkey’s celebrated call system (Cheney and Seyfarth 1990) is “functionally referential” in context, their calls have no explicit meaning since they lack “any propositional structure”. From this they conclude: