Do chimpanzee pant hoots have semantic content?

I read with great interest the exciting study by Leroux et al. [(2021) Anim Behav 179, 49–50] who investigated the nature of pant-hoot–food-call combinations in a community of wild chimpanzees (Pan troglodytes schweinfurthii) at the Budongo Conservation Field Station, Budongo Forest, Uganda. The authors propose, among others, that they reveal the first evidence that wild chimpanzees are able “to combine meaning-bearing units into larger structures” (i.e., that they are capable of semantic compositionality and, by extension, syntax). Their analysis represents an important addition to a growing body of research and discussions on communicational combinatoriality in wild primates and specifically apes, and, by extension, extinct hominins. Incidentally, I have recently published a paper in Animal Cognition in which I also suggested, based on a reanalysis of existing data, that wild chimpanzees can display semantic compositionality and syntax in their communication [Gabrić (2021) Anim Cogn, online ahead of print]. In the present commentary, I argue that Leroux et al.’s (2021) interpretation of the data may be ungrounded given that (1) unlike for food calls, there is currently very little if any indication in the scientific literature that pant-hoots have semantic content (i.e., are meaningful) and given that (2) Leroux et al. (2021) did not investigate their a priori assumption that the observed pant-hoots are in fact semantic. Since pant-hoots feature prominently in the chimpanzee vocal repertoire and the debate on their eventual semanticity is still wide open, this represents a fine opportunity to revisit this issue in the context of Leroux et al.’s (2021) study. Their paper further raises several other less significant questions.

Overlooked evidence for semantic compositionality and signal reduction in wild chimpanzees (Pan troglodytes)

Recent discoveries of semantic compositionality in Japanese tits have enlivened the discussions on the presence of this phenomenon in wild animal communication. Data on semantic compositionality in wild apes are lacking, even though language experiments with captive apes have demonstrated they are capable of semantic compositionality. In this paper, I revisit the study by Boesch (Hum. Evol. 6:81–89, 1991) who investigated drumming sequences by an alpha male in a chimpanzee (Pan troglodytes) community in the Taï National Park, Côte d’Ivoire. A reanalysis of the data reveals that the alpha male produced semantically compositional combined messages of travel direction change and resting period initiation. Unlike the Japanese tits, the elements of the compositional expression were not simply juxtaposed but displayed structural reduction, while one of the two elements in the expression coded the meanings of both elements. These processes show relative resemblance to blending and fusion in human languages. Also unlike the tits, the elements of the compositional expression did not have a fixed order, although there was a fixed distribution of drumming events across the trees used for drumming. Because the elements of the expression appear to carry verb-like meanings, the compositional expression also resembles simple verb-verb constructions and short paratactic combinations of two clauses found across languages. In conclusion, the reanalysis suggests that semantic compositionality and phenomena resembling paratactic combinations of two clauses might have been present in the communication of the last common ancestor of chimpanzees and humans, not necessarily in the vocal modality.

On the internal structure of Serbian -(n)je nominalizations

The paper deals with the internal syntactic structure of deverbal -nje nominals in Serbian. The tests from the licensing of event-related modifiers (by-phrases and instrumental DPs) support the hypothesis that -nje nominals are derived from passive participles by adding the suffix -je (Marvin 2002; Simonović & Arsenijević 2014). Building on Simonović & Arsenijević (2014), I further observe that the licensing of referential and non-referential event modifiers exhibits a complex set of correlations with the aspectual properties of the base, phonological faithfulness to the base, and semantic compositionality. Semantic opacity and phonological unfaithfulness do not always go hand in hand, and I treat them as two separate components of a process of lexicalization, which is syntactically constrained (Marantz 1997). I argue that the presence of full VoiceP structure including a v0 referring to an event diagnosed by the licensing of referential event modifiers (Alexiadou et al. 2014) constitutes a phase, which blocks lexicalization. This structure is present in -nje nominals derived from secondary imperfectives, which always license referential event modifiers and exhibit semantic compositionality and phonological unfaithfulness. Smaller structures derived from perfectives or primary imperfectives do not license referential event modifiers (hence, they do not constitute a full phase), which is what makes them susceptible to lexicalization.

Overlooked evidence for non-juxtaposed conjunctive semantic compositionality in wild chimpanzees?

Recent discoveries of semantic compositionality in Japanese tits have enlivened the discussions on the presence of this phenomenon in animal communication. However, data on semantic compositionality in primates are lacking. In this paper, I revisit the study by Boesch [1991 (Hum Evol 6:81-89] who investigated drumming sequences by an alpha male in a chimpanzee (Pan troglodytes) community in the Taï National Park, Côte d'Ivoire. A reanalysis of the data reveals that, similar to the Japanese tits, the alpha male produced conjunctively (“additively”) combined messages of travel direction change and resting period initiation. Unlike the Japanese tits, the elements of the conjunctive message were not simply juxtaposed but displayed structural reduction reminiscent of fusion in human languages. Also unlike the Japanese tits, the elements of the conjunctive message did not pass the movement test for syntactic constituents. Additionally, limited data possibly point to processes similar to reduplication in human languages.

Reflections on Protolanguage: Evidence from Studies on Animal Communication

The paper is a critique of the existence of protolanguage based on some personal reasoning given the findings of previous research. This paper focuses on the nature of semantic compositionality and its existence (and therefore manifestations) in animal communication systems as evidence of the existence of protolanguage. This compositional state that started to color human language has paved the way to hierarchical syntax and thus has helped in the emergence of a recursive, fully complex language. On the other hand, non-human animal communication systems, including those examined in this paper, have not managed to progress beyond the holophrastic state, and thus remained highly confined and unproductive. This is explicated by the observation that these systems do not employ discrete meaningful units that can be used recursively in different linguistic contexts, a necessary condition for a system of communication to be compositional. This is interesting in the study of language evolution as it could suggest that human language could not have evolved from a rudimentary, intermediate stage called protolanguage. Speculating about the existence of protolanguage subsumes convergent evolution (e.g. songbirds). The lack of semantic compositionality in non-human communication system suggests that convergent evolution is hard to prove, which puts the existence of protolanguage on the line. This thesis is, however, far from being established and requires a lot of further research to prove its validity. Received: 21 September 2020 / Accepted: 3 November 2020 / Published: 17 January 2021

A pan-Atlantic ‘multiple modal belt’?

Multiple modality is spread across the wider Atlantic region, both within individual varieties and across variety types. Based on corpus-based evidence, it is argued that first and second tiers of multiple modals carry high diagnostic value and that regionally separated Anglophone areas differ in their preference for first- and second-tier components in modal constructions. Semantics is a diagnostic typologically as there exists a continuum, the “Multiple Modal Belt,” which consists of three main clusters that are primarily differentiated by their respective compositional preferences: North American varieties favor epistemic ‘weak probability’ elements (~might) as first-tier modals, Caribbean varieties ‘high probability’ or ‘certainty’ (~must). Multiple causation and contact-induced change are offered as explanations for supra- and sub-regional variation in the Atlantic region, and there is strong evidence that the preference for second-tier components originally represented Scottish origin and subsequent diffusion with locally differing contact scenarios. Locally distinct preferences for semantic compositionality – particularly based on preference for first-tier ‘high-probability’ modals – are used to model a geo-typological clustering of varieties throughout the wider Atlantic region.

Trying to make it work: Compositional effects in the processing of compound “nonwords”

Speakers of languages with synchronically productive compounding systems, such as English, are likely to encounter new compounds on a daily basis. These can only be useful for communication if speakers are able to rapidly compose their meanings. However, while compositional meanings can be obtained for some novel compounds such as bridgemill, this is far harder for others such as radiosauce; accordingly, processing speed should be affected by the ease of such a compositional process. To rigorously test this hypothesis, we employed a fully implemented computational model based on distributional semantics to quantitatively measure the degree of semantic compositionality of novel compounds. In two large-scale studies, we collected timed sensibility judgements and lexical decisions for hundreds of morphologically structured nonwords in English. Response times were predicted by the constituents’ semantic contribution to the compositional process, with slower rejections for more compositional nonwords. We found no indication of a difference in these compositional effects between the tasks, suggesting that speakers automatically engage in a compositional process whenever they encounter morphologically structured stimuli, even when it is not required by the task at hand. Such compositional effects in the processing of novel compounds have important implications for studies that employ such stimuli as filler material or “nonwords,” as response times for these items can differ greatly depending on their compositionality.

Sheaving—a universal construction for semantic compositionality

Semantic compositionality—the way that meanings of complex entities obtain from meanings of constituent entities and their structural relations—is supposed to explain certain concomitant cognitive capacities, such as systematicity. Yet, cognitive scientists are divided on mechanisms for compositionality: e.g. a language of thought on one side versus a geometry of thought on the other. Category theory is a field of (meta)mathematics invented to bridge formal divides. We focus on sheaving—a construction at the nexus of algebra and geometry/topology, alluding to an integrative view, to sketch out a category theory perspective on the semantics of compositionality. Sheaving is a universal construction for making inferences from local knowledge, where meaning is grounded by the underlying topological space. Three examples illustrate how topology conveys meaning, in terms of the inclusion relations between the open sets that constitute the space, though the topology is not regarded as the only source of semantic information. In this sense, category (sheaf) theory provides a general framework for semantic compositionality. This article is part of the theme issue ‘Towards mechanistic models of meaning composition’.

Trying to make it work: Compositional effects in the processing of compound "nonwords"

Speakers of languages with synchronically productive compounding systems, such as English, are likely to encounter new compounds on a daily basis. These can only be useful for communication if speakers are able to rapidly compose their meanings. However, while compositional meanings can be obtained for some novel compounds such as "bridgemill", this is far harder for others such as "radiosauce"; accordingly, processing speed should be affected by the ease of such a compositional process. To rigorously test this hypothesis, we employed a fully implemented computational model based on distributional semantics to quantitatively measure the degree of semantic compositionality of novel compounds. In two large-scale studies, we collected timed sensibility judgments and lexical decisions for hundreds of morphologically-structured nonwords in English. Response times were predicted by the constituents' semantic contribution to the compositional process, with slower rejections for more compositional nonwords. We found no indication of a difference in these compositional effects between the tasks, suggesting that speakers automatically engage in a compositional process whenever they encounter morphologically-structured stimuli, even when it is not required by the task at hand. Such compositional effects in the processing of novel compounds have important implications for studies that employ such stimuli as filler material or "nonwords", since response times for these items can differ greatly depending on their compositionality.