Concatenation of 'alert' and 'identity' segments in dingoes' alarm calls

Call combination production is linked to the social environment in Western Australian magpies (Gymnorhina tibicen dorsalis)

It has recently become clear that some language-specific traits previously thought to be unique to humans (such as the capacity to combine sounds) are widespread in the animal kingdom. Despite the increase in studies documenting the presence of call combinations in non-human animals, factors promoting this vocal trait are unclear. One leading hypothesis proposes that communicative complexity co-evolved with social complexity owing to the need to transmit a diversity of information to a wider range of social partners. The Western Australian magpie (Gymnorhina tibicen dorsalis) provides a unique model to investigate this proposed link because it is a group-living, vocal learning species that is capable of multi-level combinatoriality (independently produced calls contain vocal segments and comprise combinations). Here, we compare variations in the production of call combinations across magpie groups ranging in size from 2 to 11 birds. We found that callers in larger groups give call combinations: (i) in greater diversity and (ii) more frequently than callers in smaller groups. Significantly, these observations support the hypothesis that combinatorial complexity may be related to social complexity in an open-ended vocal learner, providing an important step in understanding the role that sociality may have played in the development of vocal combinatorial complexity. This article is part of the theme issue 'The power of sound: unravelling how acoustic communication shapes group dynamics'.

The Australasian dingo archetype: de novo chromosome-length genome assembly, DNA methylome, and cranial morphology

BACKGROUND

One difficulty in testing the hypothesis that the Australasian dingo is a functional intermediate between wild wolves and domesticated breed dogs is that there is no reference specimen. Here we link a high-quality de novo long-read chromosomal assembly with epigenetic footprints and morphology to describe the Alpine dingo female named Cooinda. It was critical to establish an Alpine dingo reference because this ecotype occurs throughout coastal eastern Australia where the first drawings and descriptions were completed.

FINDINGS

We generated a high-quality chromosome-level reference genome assembly (Canfam_ADS) using a combination of Pacific Bioscience, Oxford Nanopore, 10X Genomics, Bionano, and Hi-C technologies. Compared to the previously published Desert dingo assembly, there are large structural rearrangements on chromosomes 11, 16, 25, and 26. Phylogenetic analyses of chromosomal data from Cooinda the Alpine dingo and 9 previously published de novo canine assemblies show dingoes are monophyletic and basal to domestic dogs. Network analyses show that the mitochondrial DNA genome clusters within the southeastern lineage, as expected for an Alpine dingo. Comparison of regulatory regions identified 2 differentially methylated regions within glucagon receptor GCGR and histone deacetylase HDAC4 genes that are unmethylated in the Alpine dingo genome but hypermethylated in the Desert dingo. Morphologic data, comprising geometric morphometric assessment of cranial morphology, place dingo Cooinda within population-level variation for Alpine dingoes. Magnetic resonance imaging of brain tissue shows she had a larger cranial capacity than a similar-sized domestic dog.

CONCLUSIONS

These combined data support the hypothesis that the dingo Cooinda fits the spectrum of genetic and morphologic characteristics typical of the Alpine ecotype. We propose that she be considered the archetype specimen for future research investigating the evolutionary history, morphology, physiology, and ecology of dingoes. The female has been taxidermically prepared and is now at the Australian Museum, Sydney.

The Australasian dingo archetype: De novo chromosome-length genome assembly, DNA methylome, and cranial morphology

Background

One difficulty in testing the hypothesis that the Australasian dingo is a functional intermediate between wild wolves and domesticated breed dogs is that there is no reference specimen. Here we link a high-quality de novo long read chromosomal assembly with epigenetic footprints and morphology to describe the Alpine dingo female named Cooinda. It was critical to establish an Alpine dingo reference because this ecotype occurs throughout coastal eastern Australia where the first drawings and descriptions were completed.

Findings

We generated a high-quality chromosome-level reference genome assembly (Canfam_ADS) using a combination of Pacific Bioscience, Oxford Nanopore, 10X Genomics, Bionano, and Hi-C technologies. Compared to the previously published Desert dingo assembly, there are large structural rearrangements on Chromosomes 11, 16, 25 and 26. Phylogenetic analyses of chromosomal data from Cooinda the Alpine dingo and nine previously published de novo canine assemblies show dingoes are monophyletic and basal to domestic dogs. Network analyses show that the mtDNA genome clusters within the southeastern lineage, as expected for an Alpine dingo. Comparison of regulatory regions identified two differentially methylated regions within glucagon receptor GCGR and histone deacetylase HDAC4 genes that are unmethylated in the Alpine dingo genome but hypermethylated in the Desert dingo. Morphological data, comprising geometric morphometric assessment of cranial morphology place dingo Cooinda within population-level variation for Alpine dingoes. Magnetic resonance imaging of brain tissue show she had a larger cranial capacity than a similar-sized domestic dog.

Conclusions

These combined data support the hypothesis that the dingo Cooinda fits the spectrum of genetic and morphological characteristics typical of the Alpine ecotype. We propose that she be considered the archetype specimen for future research investigating the evolutionary history, morphology, physiology, and ecology of dingoes. The female has been taxidermically prepared and is now at the Australian Museum, Sydney.

Lessons learned in animal acoustic cognition through comparisons with humans

Humans are an interesting subject of study in comparative cognition. While humans have a lot of anecdotal and subjective knowledge about their own minds and behaviors, researchers tend not to study humans the way they study other species. Instead, comparisons between humans and other animals tend to be based on either assumptions about human behavior and cognition, or very different testing methods. Here we emphasize the importance of using insider knowledge about humans to form interesting research questions about animal cognition while simultaneously stepping back and treating humans like just another species as if one were an alien researcher. This perspective is extremely helpful to identify what aspects of cognitive processes may be interesting and relevant across the animal kingdom. Here we outline some examples of how this objective human-centric approach has helped us to move forward knowledge in several areas of animal acoustic cognition (rhythm, harmonicity, and vocal units). We describe how this approach works, what kind of benefits we obtain, and how it can be applied to other areas of animal cognition. While an objective human-centric approach is not useful when studying traits that do not occur in humans (e.g., magnetic spatial navigation), it can be extremely helpful when studying traits that are relevant to humans (e.g., communication). Overall, we hope to entice more people working in animal cognition to use a similar approach to maximize the benefits of being part of the animal kingdom while maintaining a detached and scientific perspective on the human species.

Optionality in animal communication: a novel framework for examining the evolution of arbitrariness

A critical feature of language is that the form of words need not bear any perceptual similarity to their function - these relationships can be 'arbitrary'. The capacity to process these arbitrary form-function associations facilitates the enormous expressive power of language. However, the evolutionary roots of our capacity for arbitrariness, i.e. the extent to which related abilities may be shared with animals, is largely unexamined. We argue this is due to the challenges of applying such an intrinsically linguistic concept to animal communication, and address this by proposing a novel conceptual framework highlighting a key underpinning of linguistic arbitrariness, which is nevertheless applicable to non-human species. Specifically, we focus on the capacity to associate alternative functions with a signal, or alternative signals with a function, a feature we refer to as optionality. We apply this framework to a broad survey of findings from animal communication studies and identify five key dimensions of communicative optionality: signal production, signal adjustment, signal usage, signal combinatoriality and signal perception. We find that optionality is widespread in non-human animals across each of these dimensions, although only humans demonstrate it in all five. Finally, we discuss the relevance of optionality to behavioural and cognitive domains outside of communication. This investigation provides a powerful new conceptual framework for the cross-species investigation of the origins of arbitrariness, and promises to generate original insights into animal communication and language evolution more generally.

The acoustic bases of human voice identity processing in dogs

Speech carries identity-diagnostic acoustic cues that help individuals recognize each other during vocal–social interactions. In humans, fundamental frequency, formant dispersion and harmonics-to-noise ratio serve as characteristics along which speakers can be reliably separated. The ability to infer a speaker’s identity is also adaptive for members of other species (like companion animals) for whom humans (as owners) are relevant. The acoustic bases of speaker recognition in non-humans are unknown. Here, we tested whether dogs can recognize their owner’s voice and whether they rely on the same acoustic parameters for such recognition as humans use to discriminate speakers. Stimuli were pre-recorded sentences spoken by the owner and control persons, played through loudspeakers placed behind two non-transparent screens (with each screen hiding a person). We investigated the association between acoustic distance of speakers (examined along several dimensions relevant in intraspecific voice identification) and dogs’ behavior. Dogs chose their owner’s voice more often than that of control persons’, suggesting that they can identify it. Choosing success and time spent looking in the direction of the owner’s voice were positively associated, showing that looking time is an index of the ease of choice. Acoustic distance of speakers in mean fundamental frequency and jitter were positively associated with looking time, indicating that the shorter the acoustic distance between speakers with regard to these parameters, the harder the decision. So, dogs use these cues to discriminate their owner’s voice from unfamiliar voices. These findings reveal that dogs use some but probably not all acoustic parameters that humans use to identify speakers. Although dogs can detect fine changes in speech, their perceptual system may not be fully attuned to identity-diagnostic cues in the human voice.

Dwarf mongoose alarm calls: investigating a complex non-human animal call

Communication plays a vital role in the social lives of many species and varies greatly in complexity. One possible way to increase communicative complexity is by combining signals into longer sequences, which has been proposed as a mechanism allowing species with a limited repertoire to increase their communicative output. In mammals, most studies on combinatoriality have focused on vocal communication in non-human primates. Here, we investigated a potential combination of alarm calls in the dwarf mongoose (Helogale parvula), a non-primate mammal. Acoustic analyses and playback experiments with a wild population suggest: (i) that dwarf mongooses produce a complex call type (T₃) which, at least at the surface level, seems to comprise units that are not functionally different to two meaningful alarm calls (aerial and terrestrial); and (ii) that this T₃ call functions as a general alarm, produced in response to a wide range of threats. Using a novel approach, we further explored multiple interpretations of the T₃ call based on the information content of the apparent comprising calls and how they are combined. We also considered an alternative, non-combinatorial interpretation that frames T₃ as the origin, rather than the product, of the individual alarm calls. This study complements previous knowledge of vocal combinatoriality in non-primate mammals and introduces an approach that could facilitate comparisons between different animal and human communication systems.

Combinatoriality in the vocal systems of nonhuman animals

A key challenge in the field of human language evolution is the identification of the selective conditions that gave rise to language's generative nature. Comparative data on nonhuman animals provides a powerful tool to investigate similarities and differences among nonhuman and human communication systems and to reveal convergent evolutionary mechanisms. In this article, we provide an overview of the current evidence for combinatorial structures found in the vocal system of diverse species. We show that considerable structural diversity exits across and within species in the forms of combinatorial structures used. Based on this we suggest that a fine-grained classification and differentiation of combinatoriality is a useful approach permitting systematic comparisons across animals. Specifically, this will help to identify factors that might promote the emergence of combinatoriality and, crucially, whether differences in combinatorial mechanisms might be driven by variations in social and ecological conditions or cognitive capacities. This article is categorized under: Cognitive Biology > Evolutionary Roots of Cognition Linguistics > Evolution of Language.

Hiss and snort call types of wild-living giraffes Giraffa camelopardalis: acoustic structure and context

OBJECTIVES

Vocalization as part of vigilance behaviour is widespread across animal taxa, including ruminants. Calls of wild-living giraffes have never been recorded and spectrographically investigated. This study reports the acoustic structure of vigilance-related hiss and snort calls of wild-living giraffes Giraffa camelopardalis.

RESULTS

The hiss and snort calls were emitted during five recording sessions produced by nine individual giraffes (8 adults and 1 subadult) in their natural environment in Namibia (3 individuals) and Kenya (6 individuals). These calls attended vigilance behaviour toward humans in hides or in vehicles and cheetahs as natural predators of giraffe young. This study provides spectrographic analyses of 22 hiss and 20 snort calls. The giraffe hisses were broadband vocalizations of an average duration of 0.72 s (from 0.24 to 1.04 s) and a peak frequency of 0.69 kHz. The giraffe snorts were broadband pulsed calls of an average duration of 0.28 s (from 0.13 to 0.55 s), a peak frequency at 0.20 kHz and comprised a prominent low-frequency pulsation of 23.7 pulses/s. The acoustic structure of giraffe hisses is reminiscent of vigilance-related hisses of musk deer Moschus moschiferus. Giraffe snorts differ from snorts of other ruminants by their prominent pulsed pattern.