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Childhood anxiety disorders (CAD) are a common childhood mental disorder and understanding early developmental pathways is key to prevention and early intervention. What is not understood is whether early life stress predictors of CAD might be both mediated by infant cortisol reactivity and moderated by infant attachment status. To address this question, this exploratory study draws on 190 women recruited in early pregnancy and followed together with their children until 4 years of age. Early life stress is operationalized as maternal depression measured using the Structured Clinical Interview for the DSM, Childhood Trauma Questionnaire, Parenting Stress Index, and antenatal maternal hair cortisol concentrations. Infant cortisol reactivity was measured at 12 months together with the Strange Situation Procedure and CAD assessed at 4 years of age using the Preschool Age Psychiatric Assessment. There was no direct association between attachment classification and CAD. Furthermore, infant cortisol reactivity neither mediated nor attachment moderated the association of early life stress predictors and CAD. However, only for infants with organized attachment classifications, higher maternal antenatal depression, and hair cortisol were associated with a higher risk of CAD.

A critical component of language is the ability to recombine sounds into larger structures. Although animals also reuse sound elements across call combinations to generate meaning, examples are generally limited to pairs of distinct elements, even when repertoires contain sufficient sounds to generate hundreds of combinations. This combinatoriality might be constrained by the perceptual-cognitive demands of disambiguating between complex sound sequences that share elements. We test this hypothesis by probing the capacity of chestnut-crowned babblers to process combinations of two versus three distinct acoustic elements. We found babblers responded quicker and for longer toward playbacks of recombined versus familiar bi-element sequences, but no evidence of differential responses toward playbacks of recombined versus familiar tri-element sequences, suggesting a cognitively prohibitive jump in processing demands. We propose that overcoming constraints in the ability to process increasingly complex combinatorial signals was necessary for the productive combinatoriality that is characteristic of language to emerge.

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.

Childhood anxiety disorders (CAD) are a common childhood mental disorder and understanding early developmental pathways is key to prevention and early intervention. What is not understood is whether early life stress predictors of CAD might be both mediated by infant cortisol reactivity and moderated by infant attachment status. To address this question, this exploratory study draws on 190 women recruited in early pregnancy and followed together with their children until 4 years of age. Early life stress is operationalized as maternal depression measured using the Structured Clinical Interview for the DSM, Childhood Trauma Questionnaire, Parenting Stress Index, and antenatal maternal hair cortisol concentrations. Infant cortisol reactivity was measured at 12 months together with the Strange Situation Procedure and CAD assessed at 4 years of age using the Preschool Age Psychiatric Assessment. There was no direct association between attachment classification and CAD. Furthermore, infant cortisol reactivity neither mediated nor attachment moderated the association of early life stress predictors and CAD. However, only for infants with organized attachment classifications, higher maternal antenatal depression, and hair cortisol were associated with a higher risk of CAD.

Objective: Understanding the relationship between attachment and mental health has an important role in informing management of perinatal mental disorders and for infant mental health. It has been suggested that experiences of attachment are transmitted from one generation to the next. Maternal sensitivity has been proposed as a mediator, although findings have not been as strong as hypothesised. A meta-analysis suggested that this intergenerational transmission of attachment may vary across populations with lower concordance between parent and infant attachment classifications in clinical compared to community samples. However, no previous study has examined major depression and adult attachment in pregnancy as predictors of infant–parent attachment classification at 12 months postpartum. Methods: Data were obtained on 52 first-time mothers recruited in early pregnancy, which included 22 women who met diagnostic criteria for current major depression using the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders. The Adult Attachment Interview was also administered before 20 weeks of pregnancy. A history of early trauma was measured using the Childhood Trauma Questionnaire and maternal sensitivity was measured at 6 months postpartum using the observational measure of the Emotional Availability Scales. Infant–parent attachment was measured using the Strange Situation Procedure at 12 months. Results: Overall, we found no significant association between the Adult Attachment Interview and the Strange Situation Procedure classifications. However, a combination of maternal non-autonomous attachment on the Adult Attachment Interview and major depression was a significant predictor of insecure attachment on the Strange Situation Procedure. We did not find that maternal sensitivity mediated parental and infant attachment security in this sample. Conclusion: While previous meta-analyses identified lower concordance in clinical samples

‘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.

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.