Social Mongoose Vocal Communication: Insights into the Emergence of Linguistic Combinatoriality

Abstract

Duality of patterning, language’s ability to combine sounds on two levels, phonology and syntax, is considered one of human language’s defining features, yet relatively little is known about its origins. One way to investigate this is to take a comparative approach, contrasting combinatoriality in animal vocal communication systems with phonology and syntax in human language. In my thesis, I took a comparative approach to the evolution of combinatoriality, carrying out both theoretical and empirical research. In the theoretical domain, I identified some prevalent misunderstandings in research on the emergence of combinatoriality that have propagated across disciplines. To address these misconceptions, I re-analysed existing examples of animal call combinations implementing insights from linguistics. Specifically, I showed that syntax-like combinations are more widespread in animal communication than phonology-like sequences, which, combined with the absence of phonology in some human languages, suggested that syntax may have evolved before phonology. Building on this theoretical work, I empirically explored call combinations in two species of social mongooses. I first investigated social call combinations in meerkats (Suricata suricatta), demonstrating that call combinations represented a non-negligible component of the meerkat vocal communication system and could be used flexibly across various social contexts. Furthermore, I discussed a variety of mechanisms by which these combinations could be produced. Second, I considered call combinations in predation contexts. In particular, I investigated dwarf mongoose (Helogale parvula) alarm call combinations. To do so, I documented their alarm call repertoire, showing that they emitted multiple different alarm calls, of which some were risk related and some were more predator specific. The function of the last, rarely produced, alarm calls remained ambiguous. I then demonstrated that the dwarf mongoose “type 3” (hereafter T3) alarm call represented a combination of their predator specific aerial and terrestrial alarm calls. Observational and experimental data suggested that T3 was a general alarm call with a possible meaning akin to “(aerial or terrestrial) predator”. From a linguistic perspective this combination could be interpreted as a rudimentary form of disjunction, with disjunction being a form of syntax that combines two or more units in which at least one of the propositions is true, but not necessarily both (e.g. “he is right or wrong”). To my knowledge, this would represent the first evidence for this type of combination outside of human language. The data obtained in this thesis showed that social mongooses used call combinations in all facets of their communication, from social to anti-predator situations, and indicated that both of these contexts may play a role in the evolution of combinatoriality. Furthermore, some of the combinations described in this thesis seemed to be the result of simple mechanisms far removed from the combinatoriality seen in human language, whereas others appeared to be rudimentary forms of syntax. Nevertheless, studying combinatoriality across several species’ communication systems can help not only identify the similarities and differences between animal call combinations and linguistic forms of combinatoriality but also, ultimately, help elucidate the impact of different factors, both social and environmental, on the evolution of combinatoriality.