We argue that female Diana monkeys (Cercopithecus diana) can form complex calls by combining an A call with other elementary calls. We reject (on both empirical and conceptual grounds) a combination-free analysis based on accidental homophony, and we consider two main analyses: the Acoustic Theory takes the combination to be merely acoustic, whereas the Affixal Theory takes A to function as a suffix. We provide limited arguments for the Affixal Theory, and through comparison with another closely related monkey species, we date these combinations to at least 6 million years ago.

Modal verbs like must express two distinct non-actual meanings: deontic (e.g. obligation) and epistemic (e.g. likelihood inference). How do young children understand these modals? What factors affect their interpretation as deontic or epistemic? We report a picture preference task testing preschool children‟s interpretations of Bosnian/Croatian/Serbian (BCS) morati 'must' as deontic or epistemic. Prior work on English must shows that despite an early deontic comprehension bias at age 3, by age 5 children have flipped to a strong epistemic bias, including constructions for which adults prefer deontic interpretations (must + eventive verbs). However, properties of English leave open multiple explanations for this non-adult behaviour, as must is primarily epistemic in the input, and must + eventive verb constructions can also receive epistemic interpretations. BCS morati provides a natural comparison: morati is overwhelmingly deontic in the input, and BCS syntax provides categorical cues to deontic versus epistemic interpretation. Our results show that BCS children are more adult-like at age 3 than English children, a difference we attribute to clearer syntactic cues to flavour in BCS. But, by age 5, BCS children behave like English counterparts, selecting epistemic scenes even for constructions that are deontic-only in BCS. We argue this cross-linguistic result is best explained pragmatically: deontic uses of both morati and must invite a likelihood inference that obligations will be normatively carried out. This inference was first proposed to explain diachronic meaning changes from root > epistemic. We show older preschool children commit to this likelihood inference more than adults.

We explain why general techniques from formal linguistics can and should be applied to the analysis of monkey communication - in the areas of syntax and especially semantics. An informed look at our recent proposals shows that such techniques needn't rely excessively on categories of human language: syntax and semantics provide versatile formal tools that go beyond the specificities of human linguistics. We argue that "formal monkey linguistics" can yield new insights into monkey morphology, syntax, and semantics, as well as raise provocative new questions about the existence of a pragmatic, competition- based component in these communication systems. Finally, we argue that evolutionary questions, which are highly speculative in human language, can be addressed in an empirically satisfying fashion in primate linguistics, and we lay out problems that should be addressed at the interface between evolutionary primate linguistics and formal analyses of language evolution.