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Funder: MTA-ELTE 'Lendület' Neuroethology of Communication Research Group (Grant No. 95025), Funder: Austrian Science Fund (FWF): P33928-B, Funder: Swiss National Science Foundation (Grant code: PP00P3_163850) NCCR Evolving Language, Swiss National Science Foundation Agreement #51NF40_180888, Funder: Hungarian Academy of Sciences via the János Bolyai Research Scholarship (BO/751/20) ÚNKP-20-5; ÚNKP-21-5 and ÚNKP-22-5 New National Excellence Program of the Ministry for Innovation and Technology from the source of the National Research, Development and Innovation Fund (ÚNKP-20-5-ELTE-337; 21-5-ELTE-1061; 22-5-ELTE-475), Domestication dramatically changes behaviour, including communication, as seen in the case of dogs (Canis familiaris) and wolves (Canis lupus). We tested the hypothesis that domestication may affect an ancient, shared communication form of canids, the howling which seems to have higher individual variation in dogs: the perception and usage of howls may be affected by the genetic relatedness of the breeds to their last common ancestor with wolves (‘root distance’) and by other individual features like age, sex, and reproductive status. We exposed 68 purebred dogs to wolf howl playbacks and recorded their responses. We identified an interaction between root distance and age on the dogs’ vocal and behavioural responses: older dogs from more ancient breeds responded longer with howls and showed more stress behaviours. Our results suggest that domestication impacts vocal behaviour significantly: disintegrating howling, a central, species-specific communication form of canids and gradually eradicating it from dogs’ repertoire.

‘Pant-hoot displays’ are a species-typical, multi-modal communicative behaviour in chimpanzees in which pant-hoot vocalisations are combined with varied behavioural displays. In both captivity and the wild, individuals commonly incorporate striking or throwing elements of their environment into these displays. In this case study, we present five videos of an unenculturated, captive, adult male chimpanzee combining a large rubber feeding tub with excelsior (wood wool) in a multi-step process, which was then integrated into the subject’s pant-hoot displays as a percussive tool or ‘instrument’. During the construction process, the subject demonstrated an understanding of the relevant properties of these materials, ‘repairing’ the tub to be a more functional drum when necessary. We supplement these videos with a survey of care staff from the study site for additional detail and context. Although care must be taken in generalising data from a single individual, the behaviour reported here hints at three intriguing features of chimpanzee communicative cognition: (1) it suggests a degree of voluntary control over vocal production, (2) it is a so-far unique example of compound tool innovation and use in communicative behaviour and (3) it may represent an example of forward planning in communicative behaviour. Each of these would represent hitherto undocumented dimensions of flexibility in chimpanzee communication, mapping fertile ground for future research.

Perinatal depression is a serious mental health concern affecting 10–15% of all mothers in Western societies (Gavin et al., 2005). Perinatal depression does not only negatively impact on the mother, but may also result in a disordered mother-infant relationship with long-term negative consequences for the developing child (Sherry, Evinder, Stewart, 2003; Murray & Cooper, 1997). Low social support has been identified as an important risk factor for developing perinatal mental health problems (Razurel & Kaiser, 2015), and in particular postpartum depression (Robertson et al., 2004). Although beneficial influences of partner support are well-documented (Yim et al., 2015), influences of grandparental support on postpartum maternal mental health have received less attention. In a recent meta-analysis, we found that support from grandparents was related to better maternal mental health in the first year after child birth (Riem et al., 2023). These findings suggest that involved grandparents constitute a protective factor against the development of maternal postpartum mental health problems. It is, however, unknown how grandparental support with caregiving relates to maternal mental health in clinical samples. The lack of attention to grandparental caregiving roles is surprising, given that grandparents often play a role in childcare. In Western societies, more grandparents are currently involved in care for grandchildren than at any other time in recent history, possibly due to increasing rates of single motherhood and female employment (Shorey & Debby, 2020). These grandparental contributions appear crucial for parental wellbeing. Practical childcare support from grandparents may lower the burden of childcare, which contributes to maternal wellbeing and may also support mothers’ return to paid work. This, in turn, can facilitate an adaptive transition to motherhood. In addition to practical support, grandparents may also provide emotional support to mothers, for example by giving advice or when mothers share concerns about the infant (Aubel, 2021). However, intergenerational conflicts may hinder beneficial effects of grandparental support and may result in lower levels of perceived support. Grandparental support may not only promote maternal mental health, but also child development. A large number of studies has shown that grandparental childcare is positively related to children’s socio-emotional and cognitive development (Sadruddin et al., 2019). Grandparental support may be particularly important for children who grow up under adverse circumstances, such as parental illness. Indeed, a longitudinal study showed that a high quality relationship with grandparents attenuates the risk of transmission of maternal depressive symptoms to grandchildren, thus pointing to a buffering effect of grandparental involvement (Silverstein & Ruiz, 2006). It is, however, yet unknown whether grandparents can buffer effects of maternal depression in clinical samples. In the current study, we will examine the role of grandparental support in reducing perinatal depression. We will examine: 1) potential differences in support from grandparents (practical support with childcare, perceived support, and geographical distance) in mothers diagnosed with postpartum depression (PPD) compared with a healthy control group; 2) associations between geographical distance, perceived grandparental support, practical childcare support and severity of depressive symptoms in mothers diagnosed with PPD; 3) buffering effects of perceived grandparental support against parenting difficulties in mothers with PPD.

Data file and R scripts for Watson et al.'s "Wolf howls encode both sender- and context-specific information"

Supplemental material, sj-docx-1-anp-10.1177_00048674221106915 for Depression and antidepressant treatment in the development of hypertensive disorders of pregnancy: Results from a prospective cohort study by Megan Galbally, Stuart J Watson and Olav Spigset in Australian & New Zealand Journal of Psychiatry

International audience; A critical feature of language is that the form of words need not bear any perceptual similarity to their functionthese 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.

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Supplementary Methods and Results concerning Bayesian analyses

Menzerath's law, traditionally framed as a negative relationship between the size of a structure and its constituent parts (e.g. sentences with more clauses have shorter clauses), is widespread across information-coding systems ranging from human language and the vocal and gestural sequences of primates and birds, to the building blocks of DNA, genes and proteins. Here, we analysed an extensive dataset of ‘close-call' sequences produced by wild mountain gorillas (Gorilla beringei beringei, N individuals = 10, N sequences = 2189) to determine whether, in accordance with Menzerath's law, a negative relationship existed between the number of vocal units in a sequence and the duration of its comprising units. We initially found positive evidence for this but, on closer inspection, the negative relationship was driven entirely by the difference between single- and multi-unit (two-to-six units) sequences. Once single-unit sequences were excluded from the analysis, we identified a relationship in the opposite direction, with longer sequences generally composed of longer units. The close-call sequences of mountain gorillas therefore represent an intriguing example of a non-human vocal system which only partially conforms to the predictions of Menzerath's law.

70% of patients with schizophrenia suffer from auditory verbal hallucinations (AVH) which are frequently described as distressing and disabling. The content of AVH, in relation to internal thought, has never been linguistically tested in a self-monitoring study. The aim of this preliminary study was to establish if there was a significant difference between AVH and inner thoughts on the key linguistic parameters of valence (pleasantness), dominance (control) and arousal (intensity of emotion produced). Six volunteers with a diagnosis of schizophrenia from voice hearing support groups produced real-time, detailed diaries of AVH and inner thoughts using randomised/fixed timers. Analysis of content was completed using an established linguistic database. AVH were significantly more unpleasant and controlling but not more emotionally arousing than inner thoughts. Psychoeducation around the experience of hallucination in schizophrenia should include information that the voices will be significantly more unpleasant and controlling than their own thoughts but not more emotionally arousing. CBT might therefore include the use of compassion focussed techniques to help with the unpleasantness of AVH and schema level techniques to improve coping with the dominance of AVH.

SummaryOne standout feature of human language is our ability to reference external objects and events with socially learned symbols, or words. Exploring the phylogenetic origins of this capacity is therefore key to a comprehensive understanding of the evolution of language. While non-human primates can produce vocalizations that refer to external objects in the environment, it is generally accepted that their acoustic structure is fixed and a product of arousal states [1]. Indeed, it has been argued that the apparent lack of flexible control over the structure of referential vocalizations represents a key discontinuity with language [2]. Here, we demonstrate vocal learning in the acoustic structure of referential food grunts in captive chimpanzees. We found that, following the integration of two groups of adult chimpanzees, the acoustic structure of referential food grunts produced for a specific food converged over 3 years. Acoustic convergence arose independently of preference for the food, and social network analyses indicated this only occurred after strong affiliative relationships were established between the original subgroups. We argue that these data represent the first evidence of non-human animals actively modifying and socially learning the structure of a meaningful referential vocalization from conspecifics. Our findings indicate that primate referential call structure is not simply determined by arousal and that the socially learned nature of referential words in humans likely has ancient evolutionary origins.