Andrea Ravignani

Publications

Displaying 1 - 100 of 117
  • Bianco, R., Zuk, N. J., Bigand, F., Quarta, E., Grasso, S., Arnese, F., Ravignani, A., Battaglia-Mayer, A., & Novembre, G. (2024). Neural encoding of musical expectations in a non-human primate. Current Biology, 34(2), 444-450. doi:10.1016/j.cub.2023.12.019.

    Abstract

    The appreciation of music is a universal trait of humankind.1,2,3 Evidence supporting this notion includes the ubiquity of music across cultures4,5,6,7 and the natural predisposition toward music that humans display early in development.8,9,10 Are we musical animals because of species-specific predispositions? This question cannot be answered by relying on cross-cultural or developmental studies alone, as these cannot rule out enculturation.11 Instead, it calls for cross-species experiments testing whether homologous neural mechanisms underlying music perception are present in non-human primates. We present music to two rhesus monkeys, reared without musical exposure, while recording electroencephalography (EEG) and pupillometry. Monkeys exhibit higher engagement and neural encoding of expectations based on the previously seeded musical context when passively listening to real music as opposed to shuffled controls. We then compare human and monkey neural responses to the same stimuli and find a species-dependent contribution of two fundamental musical features—pitch and timing12—in generating expectations: while timing- and pitch-based expectations13 are similarly weighted in humans, monkeys rely on timing rather than pitch. Together, these results shed light on the phylogeny of music perception. They highlight monkeys’ capacity for processing temporal structures beyond plain acoustic processing, and they identify a species-dependent contribution of time- and pitch-related features to the neural encoding of musical expectations.
  • Kocsis, K., Düngen, D., Jadoul, Y., & Ravignani, A. (2024). Harbour seals use rhythmic percussive signalling in interaction and display. Animal Behaviour, 207, 223-234. doi:10.1016/j.anbehav.2023.09.014.

    Abstract

    Multimodal rhythmic signalling abounds across animal taxa. Studying its mechanisms and functions can highlight adaptive components in highly complex rhythmic behaviours, like dance and music. Pinnipeds, such as the harbour seal, Phoca vitulina, are excellent comparative models to assess rhythmic capacities. Harbour seals engage in rhythmic percussive behaviours which, until now, have not been described in detail. In our study, eight zoo-housed harbour seals (two pups, two juveniles and four adults) were passively monitored by audio and video during their pupping/breeding season. All juvenile and adult animals performed percussive signalling with their fore flippers in agonistic conditions, both on land and in water. Flipper slap sequences produced on the ground or on the seals' bodies were often highly regular in their interval duration, that is, were quasi-isochronous, at a 200–600 beats/min pace. Three animals also showed significant lateralization in slapping. In contrast to slapping on land, display slapping in water, performed only by adult males, showed slower tempo by one order of magnitude, and a rather motivic temporal structure. Our work highlights that percussive communication is a significant part of harbour seals' behavioural repertoire. We hypothesize that its forms of rhythm production may reflect adaptive functions such as regulating internal states and advertising individual traits.
  • Lameira, A. R., Hardus, M. E., Ravignani, A., Raimondi, T., & Gamba, M. (2024). Recursive self-embedded vocal motifs in wild orangutans. eLife, 12: RP88348. doi:10.7554/eLife.88348.3.

    Abstract

    Recursive procedures that allow placing a vocal signal inside another of a similar kind provide a neuro-computational blueprint for syntax and phonology in spoken language and human song. There are, however, no known vocal sequences among nonhuman primates arranged in self-embedded patterns that evince vocal recursion or potential incipient or evolutionary transitional forms thereof, suggesting a neuro-cognitive transformation exclusive to humans. Here, we uncover that wild flanged male orangutan long calls feature rhythmically isochronous call sequences nested within isochronous call sequences, consistent with two hierarchical strata. Remarkably, three temporally and acoustically distinct call rhythms in the lower stratum were not related to the overarching rhythm at the higher stratum by any low multiples, which suggests that these recursive structures were neither the result of parallel non-hierarchical procedures nor anatomical artifacts of bodily constraints or resonances. Findings represent a case of temporally recursive hominid vocal combinatorics in the absence of syntax, semantics, phonology, or music. Second-order combinatorics, ‘sequences within sequences’, involving hierarchically organized and cyclically structured vocal sounds in ancient hominids may have preluded the evolution of recursion in modern language-able humans.
  • Leonetti, S., Cimarelli, G., Hersh, T. A., & Ravignani, A. (2024). Why do dogs wag their tails? Biology Letters, 20(1): 20230407. doi:10.1098/rsbl.2023.0407.

    Abstract

    Tail wagging is a conspicuous behaviour in domestic dogs (Canis familiaris). Despite how much meaning humans attribute to this display, its quantitative description and evolutionary history are rarely studied. We summarize what is known about the mechanism, ontogeny, function and evolution of this behaviour. We suggest two hypotheses to explain its increased occurrence and frequency in dogs compared to other canids. During the domestication process, enhanced rhythmic tail wagging behaviour could have (i) arisen as a by-product of selection for other traits, such as docility and tameness, or (ii) been directly selected by humans, due to our proclivity for rhythmic stimuli. We invite testing of these hypotheses through neurobiological and ethological experiments, which will shed light on one of the most readily observed yet understudied animal behaviours. Targeted tail wagging research can be a window into both canine ethology and the evolutionary history of characteristic human traits, such as our ability to perceive and produce rhythmic behaviours.
  • Osiecka, A. N., Fearey, J., Ravignani, A., & Burchardt, L. (2024). Isochrony in barks of Cape fur seal (Arctocephalus pusillus pusillus) pups and adults. Ecology and Evolution, 14(3): e11085. doi:10.1002/ece3.11085.

    Abstract

    Animal vocal communication often relies on call sequences. The temporal patterns of such sequences can be adjusted to other callers, follow complex rhythmic structures or exhibit a metronome-like pattern (i.e., isochronous). How regular are the temporal patterns in animal signals, and what influences their precision? If present, are rhythms already there early in ontogeny? Here, we describe an exploratory study of Cape fur seal (Arctocephalus pusillus pusillus) barks—a vocalisation type produced across many pinniped species in rhythmic, percussive bouts. This study is the first quantitative description of barking in Cape fur seal pups. We analysed the rhythmic structures of spontaneous barking bouts of pups and adult females from the breeding colony in Cape Cross, Namibia. Barks of adult females exhibited isochrony, that is they were produced at fairly regular points in time. Instead, intervals between pup barks were more variable, that is skipping a bark in the isochronous series occasionally. In both age classes, beat precision, that is how well the barks followed a perfect template, was worse when barking at higher rates. Differences could be explained by physiological factors, such as respiration or arousal. Whether, and how, isochrony develops in this species remains an open question. This study provides evidence towards a rhythmic production of barks in Cape fur seal pups and lays the groundwork for future studies to investigate the development of rhythm using multidimensional metrics.
  • Van der Werff, J., Ravignani, A., & Jadoul, Y. (2024). thebeat: A Python package for working with rhythms and other temporal sequences. Behavior Research Methods. Advance online publication. doi:10.3758/s13428-023-02334-8.

    Abstract

    thebeat is a Python package for working with temporal sequences and rhythms in the behavioral and cognitive sciences, as well as in bioacoustics. It provides functionality for creating experimental stimuli, and for visualizing and analyzing temporal data. Sequences, sounds, and experimental trials can be generated using single lines of code. thebeat contains functions for calculating common rhythmic measures, such as interval ratios, and for producing plots, such as circular histograms. thebeat saves researchers time when creating experiments, and provides the first steps in collecting widely accepted methods for use in timing research. thebeat is an open-source, on-going, and collaborative project, and can be extended for use in specialized subfields. thebeat integrates easily with the existing Python ecosystem, allowing one to combine our tested code with custom-made scripts. The package was specifically designed to be useful for both skilled and novice programmers. thebeat provides a foundation for working with temporal sequences onto which additional functionality can be built. This combination of specificity and plasticity should facilitate research in multiple research contexts and fields of study.
  • Anichini, M., de Reus, K., Hersh, T. A., Valente, D., Salazar-Casals, A., Berry, C., Keller, P. E., & Ravignani, A. (2023). Measuring rhythms of vocal interactions: A proof of principle in harbour seal pups. Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, 378(1875): 20210477. doi:10.1098/rstb.2021.0477.

    Abstract

    Rhythmic patterns in interactive contexts characterize human behaviours such as conversational turn-taking. These timed patterns are also present in other animals, and often described as rhythm. Understanding fine-grained temporal adjustments in interaction requires complementary quantitative methodologies. Here, we showcase how vocal interactive rhythmicity in a non-human animal can be quantified using a multi-method approach. We record vocal interactions in harbour seal pups (Phoca vitulina) under controlled conditions. We analyse these data by combining analytical approaches, namely categorical rhythm analysis, circular statistics and time series analyses. We test whether pups' vocal rhythmicity varies across behavioural contexts depending on the absence or presence of a calling partner. Four research questions illustrate which analytical approaches are complementary versus orthogonal. For our data, circular statistics and categorical rhythms suggest that a calling partner affects a pup's call timing. Granger causality suggests that pups predictively adjust their call timing when interacting with a real partner. Lastly, the ADaptation and Anticipation Model estimates statistical parameters for a potential mechanism of temporal adaptation and anticipation. Our analytical complementary approach constitutes a proof of concept; it shows feasibility in applying typically unrelated techniques to seals to quantify vocal rhythmic interactivity across behavioural contexts.

    Additional information

    supplemental information
  • Düngen, D., Fitch, W. T., & Ravignani, A. (2023). Hoover the talking seal [quick guide]. Current Biology, 33, R50-R52. doi:10.1016/j.cub.2022.12.023.
  • Düngen, D., & Ravignani, A. (2023). The paradox of learned song in a semi-solitary mammal. Ethology, 129(9), 445-497. doi:10.1111/eth.13385.

    Abstract

    Learning can occur via trial and error; however, learning from conspecifics is faster and more efficient. Social animals can easily learn from conspecifics, but how do less social species learn? In particular, birds provide astonishing examples of social learning of vocalizations, while vocal learning from conspecifics is much less understood in mammals. We present a hypothesis aimed at solving an apparent paradox: how can harbor seals (Phoca vitulina) learn their song when their whole lives are marked by loose conspecific social contact? Harbor seal pups are raised individually by their mostly silent mothers. Pups' first few weeks of life show developed vocal plasticity; these weeks are followed by relatively silent years until sexually mature individuals start singing. How can this rather solitary life lead to a learned song? Why do pups display vocal plasticity at a few weeks of age, when this is apparently not needed? Our hypothesis addresses these questions and tries to explain how vocal learning fits into the natural history of harbor seals, and potentially other less social mammals. We suggest that harbor seals learn during a sensitive period within puppyhood, where they are exposed to adult males singing. In particular, we hypothesize that, to make this learning possible, the following happens concurrently: (1) mothers give birth right before male singing starts, (2) pups enter a sensitive learning phase around weaning time, which (3) coincides with their foraging expeditions at sea which, (4) in turn, coincide with the peak singing activity of adult males. In other words, harbor seals show vocal learning as pups so they can acquire elements of their future song from adults, and solitary adults can sing because they have acquired these elements as pups. We review the available evidence and suggest that pups learn adult vocalizations because they are born exactly at the right time to eavesdrop on singing adults. We conclude by advancing empirical predictions and testable hypotheses for future work.
  • Düngen, D., Sarfati, M., & Ravignani, A. (2023). Cross-species research in biomusicality: Methods, pitfalls, and prospects. In E. H. Margulis, P. Loui, & D. Loughridge (Eds.), The science-music borderlands: Reckoning with the past and imagining the future (pp. 57-95). Cambridge, MA, USA: The MIT Press. doi:10.7551/mitpress/14186.003.0008.
  • Fiveash, A., Ferreri, L., Bouwer, F. L., Kösem, A., Moghimi, S., Ravignani, A., Keller, P. E., & Tillmann, B. (2023). Can rhythm-mediated reward boost learning, memory, and social connection? Perspectives for future research. Neuroscience and Biobehavioral Reviews, 149: 105153. doi:10.1016/j.neubiorev.2023.105153.

    Abstract

    Studies of rhythm processing and of reward have progressed separately, with little connection between the two. However, consistent links between rhythm and reward are beginning to surface, with research suggesting that synchronization to rhythm is rewarding, and that this rewarding element may in turn also boost this synchronization. The current mini review shows that the combined study of rhythm and reward can be beneficial to better understand their independent and combined roles across two central aspects of cognition: 1) learning and memory, and 2) social connection and interpersonal synchronization; which have so far been studied largely independently. From this basis, it is discussed how connections between rhythm and reward can be applied to learning and memory and social connection across different populations, taking into account individual differences, clinical populations, human development, and animal research. Future research will need to consider the rewarding nature of rhythm, and that rhythm can in turn boost reward, potentially enhancing other cognitive and social processes.
  • De Gregorio, C., Raimondi, T., Bevilacqua, V., Pertosa, C., Valente, D., Carugati, F., Bandoli, F., Favaro, L., Lefaux, B., Ravignani, A., & Gamba, M. (2023). Isochronous singing in 3 crested gibbon species (Nomascusspp.). Current Zoology. Advance online publication. doi:10.1093/cz/zoad029.

    Abstract

    The search for common characteristics between the musical abilities of humans and other animal species is still taking its first steps. One of the most promising aspects from a comparative point of view is the analysis of rhythmic components, which are crucial features of human communicative performance but also well-identifiable patterns in the vocal displays of other species. Therefore, the study of rhythm is becoming essential to understand the mechanisms of singing behavior and the evolution of human communication. Recent findings provided evidence that particular rhythmic structures occur in human music and some singing animal species, such as birds and rock hyraxes, but only 2 species of nonhuman primates have been investigated so far (Indri indri and Hylobates lar). Therefore, our study aims to consistently broaden the list of species studied regarding the presence of rhythmic categories. We investigated the temporal organization in the singing of 3 species of crested gibbons (Nomascus gabriellae, Nomascus leucogenys, and Nomascus siki) and found that the most prominent rhythmic category was isochrony. Moreover, we found slight variation in songs’ tempo among species, with N. gabriellae and N. siki singing with a temporal pattern involving a gradually increasing tempo (a musical accelerando), and N. leucogenys with a more regular pattern. Here, we show how the prominence of a peak at the isochrony establishes itself as a shared characteristic in the small apes considered so far.

    Additional information

    table SM1
  • Hersh, T. A., Ravignani, A., & Burchardt, L. (2023). Robust rhythm reporting will advance ecological and evolutionary research. Methods in Ecology and Evolution, 14(6), 1398-1407. doi:10.1111/2041-210X.14118.

    Abstract


    Rhythmicity in the millisecond to second range is a fundamental building block of communication and coordinated movement. But how widespread are rhythmic capacities across species, and how did they evolve under different environmental pressures? Comparative research is necessary to answer these questions but has been hindered by limited crosstalk and comparability among results from different study species.
    Most acoustics studies do not explicitly focus on characterising or quantifying rhythm, but many are just a few scrapes away from contributing to and advancing the field of comparative rhythm research. Here, we present an eight-level rhythm reporting framework which details actionable steps researchers can take to report rhythm-relevant metrics. Levels fall into two categories: metric reporting and data sharing. Metric reporting levels include defining rhythm-relevant metrics, providing point estimates of temporal interval variability, reporting interval distributions, and conducting rhythm analyses. Data sharing levels are: sharing audio recordings, sharing interval durations, sharing sound element start and end times, and sharing audio recordings with sound element start/end times.
    Using sounds recorded from a sperm whale as a case study, we demonstrate how each reporting framework level can be implemented on real data. We also highlight existing best practice examples from recent research spanning multiple species. We clearly detail how engagement with our framework can be tailored case-by-case based on how much time and effort researchers are willing to contribute. Finally, we illustrate how reporting at any of the suggested levels will help advance comparative rhythm research.
    This framework will actively facilitate a comparative approach to acoustic rhythms while also promoting cooperation and data sustainability. By quantifying and reporting rhythm metrics more consistently and broadly, new avenues of inquiry and several long-standing, big picture research questions become more tractable. These lines of research can inform not only about the behavioural ecology of animals but also about the evolution of rhythm-relevant phenomena and the behavioural neuroscience of rhythm production and perception. Rhythm is clearly an emergent feature of life; adopting our framework, researchers from different fields and with different study species can help understand why.

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    Research Data availability
  • Jadoul, Y., & Ravignani, A. (2023). Modelling the emergence of synchrony from decentralized rhythmic interactions in animal communication. Proceedings of the Royal Society B: Biological Sciences, 290(2003). doi:10.1098/rspb.2023.0876.

    Abstract

    To communicate, an animal's strategic timing of rhythmic signals is crucial. Evolutionary, game-theoretical, and dynamical systems models can shed light on the interaction between individuals and the associated costs and benefits of signalling at a specific time. Mathematical models that study rhythmic interactions from a strategic or evolutionary perspective are rare in animal communication research. But new inspiration may come from a recent game theory model of how group synchrony emerges from local interactions of oscillatory neurons. In the study, the authors analyse when the benefit of joint synchronization outweighs the cost of individual neurons sending electrical signals to each other. They postulate there is a benefit for pairs of neurons to fire together and a cost for a neuron to communicate. The resulting model delivers a variant of a classical dynamical system, the Kuramoto model. Here, we present an accessible overview of the Kuramoto model and evolutionary game theory, and of the 'oscillatory neurons' model. We interpret the model's results and discuss the advantages and limitations of using this particular model in the context of animal rhythmic communication. Finally, we sketch potential future directions and discuss the need to further combine evolutionary dynamics, game theory and rhythmic processes in animal communication studies.
  • Jadoul, Y., Düngen, D., & Ravignani, A. (2023). PyGellermann: a Python tool to generate pseudorandom series for human and non-human animal behavioural experiments. BMC Research Notes, 16: 135. doi:10.1186/s13104-023-06396-x.

    Abstract

    Objective

    Researchers in animal cognition, psychophysics, and experimental psychology need to randomise the presentation order of trials in experimental sessions. In many paradigms, for each trial, one of two responses can be correct, and the trials need to be ordered such that the participant’s responses are a fair assessment of their performance. Specifically, in some cases, especially for low numbers of trials, randomised trial orders need to be excluded if they contain simple patterns which a participant could accidentally match and so succeed at the task without learning.
    Results

    We present and distribute a simple Python software package and tool to produce pseudorandom sequences following the Gellermann series. This series has been proposed to pre-empt simple heuristics and avoid inflated performance rates via false positive responses. Our tool allows users to choose the sequence length and outputs a .csv file with newly and randomly generated sequences. This allows behavioural researchers to produce, in a few seconds, a pseudorandom sequence for their specific experiment. PyGellermann is available at https://github.com/YannickJadoul/PyGellermann.
  • Jadoul, Y., De Boer, B., & Ravignani, A. (2023). Parselmouth for bioacoustics: Automated acoustic analysis in Python. Bioacoustics. Advance online publication. doi:10.1080/09524622.2023.2259327.

    Abstract

    Bioacoustics increasingly relies on large datasets and computational methods. The need to batch-process large amounts of data and the increased focus on algorithmic processing require software tools. To optimally assist in a bioacoustician’s workflow, software tools need to be as simple and effective as possible. Five years ago, the Python package Parselmouth was released to provide easy and intuitive access to all functionality in the Praat software. Whereas Praat is principally designed for phonetics and speech processing, plenty of bioacoustics studies have used its advanced acoustic algorithms. Here, we evaluate existing usage of Parselmouth and discuss in detail several studies which used the software library. We argue that Parselmouth has the potential to be used even more in bioacoustics research, and suggest future directions to be pursued with the help of Parselmouth.
  • Lumaca, M., Bonetti, L., Brattico, E., Baggio, G., Ravignani, A., & Vuust, P. (2023). High-fidelity transmission of auditory symbolic material is associated with reduced right–left neuroanatomical asymmetry between primary auditory regions. Cerebral Cortex, 33(11), 6902-6919. doi:10.1093/cercor/bhad009.

    Abstract

    The intergenerational stability of auditory symbolic systems, such as music, is thought to rely on brain processes that allow the faithful transmission of complex sounds. Little is known about the functional and structural aspects of the human brain which support this ability, with a few studies pointing to the bilateral organization of auditory networks as a putative neural substrate. Here, we further tested this hypothesis by examining the role of left–right neuroanatomical asymmetries between auditory cortices. We collected neuroanatomical images from a large sample of participants (nonmusicians) and analyzed them with Freesurfer’s surface-based morphometry method. Weeks after scanning, the same individuals participated in a laboratory experiment that simulated music transmission: the signaling games. We found that high accuracy in the intergenerational transmission of an artificial tone system was associated with reduced rightward asymmetry of cortical thickness in Heschl’s sulcus. Our study suggests that the high-fidelity copying of melodic material may rely on the extent to which computational neuronal resources are distributed across hemispheres. Our data further support the role of interhemispheric brain organization in the cultural transmission and evolution of auditory symbolic systems.
  • Raimondi, T., Di Panfilo, G., Pasquali, M., Zarantonello, M., Favaro, L., Savini, T., Gamba, M., & Ravignani, A. (2023). Isochrony and rhythmic interaction in ape duetting. Proceedings of the Royal Society B: Biological Sciences, 290: 20222244. doi:10.1098/rspb.2022.2244.

    Abstract

    How did rhythm originate in humans, and other species? One cross-cultural universal, frequently found in human music, is isochrony: when note onsets repeat regularly like the ticking of a clock. Another universal consists in synchrony (e.g. when individuals coordinate their notes so that they are sung at the same time). An approach to biomusicology focuses on similarities and differences across species, trying to build phylogenies of musical traits. Here we test for the presence of, and a link between, isochrony and synchrony in a non-human animal. We focus on the songs of one of the few singing primates, the lar gibbon (Hylobates lar), extracting temporal features from their solo songs and duets. We show that another ape exhibits one rhythmic feature at the core of human musicality: isochrony. We show that an enhanced call rate overall boosts isochrony, suggesting that respiratory physiological constraints play a role in determining the song's rhythmic structure. However, call rate alone cannot explain the flexible isochrony we witness. Isochrony is plastic and modulated depending on the context of emission: gibbons are more isochronous when duetting than singing solo. We present evidence for rhythmic interaction: we find statistical causality between one individual's note onsets and the co-singer's onsets, and a higher than chance degree of synchrony in the duets. Finally, we find a sex-specific trade-off between individual isochrony and synchrony. Gibbon's plasticity for isochrony and rhythmic overlap may suggest a potential shared selective pressure for interactive vocal displays in singing primates. This pressure may have convergently shaped human and gibbon musicality while acting on a common neural primate substrate. Beyond humans, singing primates are promising models to understand how music and, specifically, a sense of rhythm originated in the primate phylogeny.
  • Ravignani, A., & Herbst, C. T. (2023). Voices in the ocean: Toothed whales evolved a third way of making sounds similar to that of land mammals and birds. Science, 379(6635), 881-882. doi:10.1126/science.adg5256.
  • Tomasek, M., Ravignani, A., Boucherie, P. H., Van Meyel, S., & Dufour, V. (2023). Spontaneous vocal coordination of vocalizations to water noise in rooks (Corvus frugilegus): An exploratory study. Ecology and Evolution, 13(2): e9791. doi:10.1002/ece3.9791.

    Abstract

    The ability to control one's vocal production is a major advantage in acoustic communication. Yet, not all species have the same level of control over their vocal output. Several bird species can interrupt their song upon hearing an external stimulus, but there is no evidence how flexible this behavior is. Most research on corvids focuses on their cognitive abilities, but few studies explore their vocal aptitudes. Recent research shows that crows can be experimentally trained to vocalize in response to a brief visual stimulus. Our study investigated vocal control abilities with a more ecologically embedded approach in rooks. We show that two rooks could spontaneously coordinate their vocalizations to a long-lasting stimulus (the sound of their small bathing pool being filled with a water hose), one of them adjusting roughly (in the second range) its vocalizations as the stimuli began and stopped. This exploratory study adds to the literature showing that corvids, a group of species capable of cognitive prowess, are indeed able to display good vocal control abilities.
  • Verga, L., Kotz, S. A., & Ravignani, A. (2023). The evolution of social timing. Physics of Life Reviews, 46, 131-151. doi:10.1016/j.plrev.2023.06.006.

    Abstract

    Sociality and timing are tightly interrelated in human interaction as seen in turn-taking or synchronised dance movements. Sociality and timing also show in communicative acts of other species that might be pleasurable, but also necessary for survival. Sociality and timing often co-occur, but their shared phylogenetic trajectory is unknown: How, when, and why did they become so tightly linked? Answering these questions is complicated by several constraints; these include the use of divergent operational definitions across fields and species, the focus on diverse mechanistic explanations (e.g., physiological, neural, or cognitive), and the frequent adoption of anthropocentric theories and methodologies in comparative research. These limitations hinder the development of an integrative framework on the evolutionary trajectory of social timing and make comparative studies not as fruitful as they could be. Here, we outline a theoretical and empirical framework to test contrasting hypotheses on the evolution of social timing with species-appropriate paradigms and consistent definitions. To facilitate future research, we introduce an initial set of representative species and empirical hypotheses. The proposed framework aims at building and contrasting evolutionary trees of social timing toward and beyond the crucial branch represented by our own lineage. Given the integration of cross-species and quantitative approaches, this research line might lead to an integrated empirical-theoretical paradigm and, as a long-term goal, explain why humans are such socially coordinated animals.
  • Gamba, M., De Gregorio, C., Valente, D., Raimondi, T., Torti, V., Miaretsoa, L., Carugati, F., Friard, O., Giacoma, C., & Ravignani, A. (2022). Primate rhythmic categories analyzed on an individual basis. In A. Ravignani, R. Asano, D. Valente, F. Ferretti, S. Hartmann, M. Hayashi, Y. Jadoul, M. Martins, Y. Oseki, E. D. Rodrigues, O. Vasileva, & S. Wacewicz (Eds.), The evolution of language: Proceedings of the Joint Conference on Language Evolution (JCoLE) (pp. 229-236). Nijmegen: Joint Conference on Language Evolution (JCoLE).

    Abstract

    Rhythm is a fundamental feature characterizing communicative displays, and recent studies showed that primate songs encompass categorical rhythms falling on small integer ratios observed in humans. We individually assessed the presence and sexual dimorphism of rhythmic categories, analyzing songs emitted by 39 wild indris. Considering the intervals between the units given during each song, we extracted 13556 interval ratios and found three peaks (at around 0.33, 0.47, and 0.70). Two peaks indicated rhythmic categories corresponding to small integer ratios (1:1, 2:1). All individuals showed a peak at 0.70, and
    most showed those at 0.47 and 0.33. In addition, we found sex differences in the peak at 0.47 only, with males showing lower values than females. This work investigates the presence of individual rhythmic categories in a non-human species; further research may highlight the significance of rhythmicity and untie selective pressures that guided its evolution across species, including humans.
  • Gamba, M., Torti, V., De Gregorio, C., Raimondi, T., Miaretsoa, L., Carugati, F., Cristiano, W., Randrianarison, R. M., Bonadonna, G., Zanoli, A., Friard, O., Valente, D., Ravignani, A., & Giacoma, C. (2022). Caractéristiques rythmiques du chant de l'indri et nouvelles perspectives pour une évaluation comparative du rythme chez les primates non humains. Revue de primatologie, 13. doi:10.4000/primatologie.14989.

    Abstract

    Since the discovery that rhythmic abilities are universal in humans, temporal features of vocal communication have greatly interested researchers studying animal communication. Rhythmic patterns are a valuable tool for species discrimination, mate choice, and individual recognition. A recent study showed that bird songs and human music share rhythmic categories when a signal's temporal intervals are distributed categorically rather than uniformly. Following that study, we aimed to investigate whether songs of indris (Indri indri), the only singing lemur, may show similar features. We measured the inter-onset intervals (tk), delimited by the onsets of two consecutive units, and the rhythmic ratios between these intervals (rk), calculated by dividing an interval by itself plus its adjacent, and finded a three-cluster distribution. Two clusters corresponded to rhythmic categories at 1:1 and 1:2, and the third approached a 2:1 ratio. Our results demonstrated for the first time that another primate besides humans produces categorical rhythms, an ability likely evolved convergently among singing species such as songbirds, indris, and humans. Understanding which communicative features are shared with other species is fundamental to understanding how they have evolved. In this regard, thanks to the simplicity of data processing and interpretation, our study relied on an accessible analytical approach that could open up new branches of the investigation into primate communication, leading the way to reconstruct a phylogeny of rhythm abilities across the entire order.
  • Oswald, J. N., Van Cise, A. M., Dassow, A., Elliott, T., Johnson, M. T., Ravignani, A., & Podos, J. (2022). A collection of best practices for the collection and analysis of bioacoustic data. Applied Sciences, 12(23): 12046. doi:10.3390/app122312046.

    Abstract

    The field of bioacoustics is rapidly developing and characterized by diverse methodologies, approaches and aims. For instance, bioacoustics encompasses studies on the perception of pure tones in meticulously controlled laboratory settings, documentation of species’ presence and activities using recordings from the field, and analyses of circadian calling patterns in animal choruses. Newcomers to the field are confronted with a vast and fragmented literature, and a lack of accessible reference papers or textbooks. In this paper we contribute towards filling this gap. Instead of a classical list of “dos” and “don’ts”, we review some key papers which, we believe, embody best practices in several bioacoustic subfields. In the first three case studies, we discuss how bioacoustics can help identify the ‘who’, ‘where’ and ‘how many’ of animals within a given ecosystem. Specifically, we review cases in which bioacoustic methods have been applied with success to draw inferences regarding species identification, population structure, and biodiversity. In fourth and fifth case studies, we highlight how structural properties in signal evolution can emerge via ecological constraints or cultural transmission. Finally, in a sixth example, we discuss acoustic methods that have been used to infer predator–prey dynamics in cases where direct observation was not feasible. Across all these examples, we emphasize the importance of appropriate recording parameters and experimental design. We conclude by highlighting common best practices across studies as well as caveats about our own overview. We hope our efforts spur a more general effort in standardizing best practices across the subareas we’ve highlighted in order to increase compatibility among bioacoustic studies and inspire cross-pollination across the discipline.
  • Ravignani, A., & Garcia, M. (2022). A cross-species framework to identify vocal learning abilities in mammals. Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, 377: 20200394. doi:10.1098/rstb.2020.0394.

    Abstract

    Vocal production learning (VPL) is the experience-driven ability to produce novel vocal signals through imitation or modification of existing vocalizations. A parallel strand of research investigates acoustic allometry, namely how information about body size is conveyed by acoustic signals. Recently, we proposed that deviation from acoustic allometry principles as a result of sexual selection may have been an intermediate step towards the evolution of vocal learning abilities in mammals. Adopting a more hypothesis-neutral stance, here we perform phylogenetic regressions and other analyses further testing a potential link between VPL and being an allometric outlier. We find that multiple species belonging to VPL clades deviate from allometric scaling but in the opposite direction to that expected from size exaggeration mechanisms. In other words, our correlational approach finds an association between VPL and being an allometric outlier. However, the direction of this association, contra our original hypothesis, may indicate that VPL did not necessarily emerge via sexual selection for size exaggeration: VPL clades show higher vocalization frequencies than expected. In addition, our approach allows us to identify species with potential for VPL abilities: we hypothesize that those outliers from acoustic allometry lying above the regression line may be VPL species. Our results may help better understand the cross-species diversity, variability and aetiology of VPL, which among other things is a key underpinning of speech in our species.

    This article is part of the theme issue ‘Voice modulation: from origin and mechanism to social impact (Part II)’.

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    Raw data Supplementary material
  • Ravignani, A., Asano, R., Valente, D., Ferretti, F., Hartmann, S., Hayashi, M., Jadoul, Y., Martins, M., Oseki, Y., Rodrigues, E. D., Vasileva, O., & Wacewicz, S. (Eds.). (2022). The evolution of language: Proceedings of the Joint Conference on Language Evolution (JCoLE). Nijmegen: Joint Conference on Language Evolution (JCoLE). doi:10.17617/2.3398549.
  • Ravignani, A. (2022). Language evolution: Sound meets gesture? [Review of the book From signal to symbol: The evolution of language by By R. Planer and K. Sterelny]. Evolutionary Anthropology, 31, 317-318. doi:10.1002/evan.21961.
  • de Reus, K., Carlson, D., Lowry, A., Gross, S., Garcia, M., Rubio-García, A., Salazar-Casals, A., & Ravignani, A. (2022). Body size predicts vocal tract size in a mammalian vocal learner. In A. Ravignani, R. Asano, D. Valente, F. Ferretti, S. Hartmann, M. Hayashi, Y. Jadoul, M. Martins, Y. Oseki, E. D. Rodrigues, O. Vasileva, & S. Wacewicz (Eds.), The evolution of language: Proceedings of the Joint Conference on Language Evolution (JCoLE) (pp. 154-156). Nijmegen: Joint Conference on Language Evolution (JCoLE).
  • de Reus, K., Carlson, D., Lowry, A., Gross, S., Garcia, M., Rubio-Garcia, A., Salazar-Casals, A., & Ravignani, A. (2022). Vocal tract allometry in a mammalian vocal learner. Journal of Experimental Biology, 225(8): jeb243766. doi:10.1242/jeb.243766.

    Abstract

    Acoustic allometry occurs when features of animal vocalisations can be predicted from body size measurements. Despite this being considered the norm, allometry sometimes breaks, resulting in species sounding smaller or larger than expected. A recent hypothesis suggests that allometry-breaking animals cluster into two groups: those with anatomical adaptations to their vocal tracts and those capable of learning new sounds (vocal learners). Here we test this hypothesis by probing vocal tract allometry in a proven mammalian vocal learner, the harbour seal (Phoca vitulina). We test whether vocal tract structures and body size scale allometrically in 68 individuals. We find that both body length and body weight accurately predict vocal tract length and one tracheal dimension. Independently, body length predicts vocal fold length while body weight predicts a second tracheal dimension. All vocal tract measures are larger in weaners than in pups and some structures are sexually dimorphic within age classes. We conclude that harbour seals do comply with allometric constraints, lending support to our hypothesis. However, allometry between body size and vocal fold length seems to emerge after puppyhood, suggesting that ontogeny may modulate the anatomy-learning distinction previously hypothesised as clear-cut. Species capable of producing non-allometric signals while their vocal tract scales allometrically, like seals, may then use non-morphological allometry-breaking mechanisms. We suggest that seals, and potentially other vocal learning mammals, may achieve allometry-breaking through developed neural control over their vocal organs.
  • Verga, L., Sroka, M. G. U., Varola, M., Villanueva, S., & Ravignani, A. (2022). Spontaneous rhythm discrimination in a mammalian vocal learner. Biology Letters, 18: 20220316. doi:10.1098/rsbl.2022.0316.

    Abstract

    Rhythm and vocal production learning are building blocks of human music and speech. Vocal learning has been hypothesized as a prerequisite for rhythmic capacities. Yet, no mammalian vocal learner but humans have shown the capacity to flexibly and spontaneously discriminate rhythmic patterns. Here we tested untrained rhythm discrimination in a mammalian vocal learning species, the harbour seal (Phoca vitulina). Twenty wild-born seals were exposed to music-like playbacks of conspecific call sequences varying in basic rhythmic properties. These properties were called length, sequence regularity, and overall tempo. All three features significantly influenced seals' reaction (number of looks and their duration), demonstrating spontaneous rhythm discrimination in a vocal learning mammal. This finding supports the rhythm–vocal learning hypothesis and showcases pinnipeds as promising models for comparative research on rhythmic phylogenies.
  • Fink, B., Bläsing, B., Ravignani, A., & Shackelford, T. K. (2021). Evolution and functions of human dance. Evolution and Human Behavior, 42(4), 351-360. doi:10.1016/j.evolhumbehav.2021.01.003.

    Abstract

    Dance is ubiquitous among humans and has received attention from several disciplines. Ethnographic documentation suggests that dance has a signaling function in social interaction. It can influence mate preferences and facilitate social bonds. Research has provided insights into the proximate mechanisms of dance, individually or when dancing with partners or in groups. Here, we review dance research from an evolutionary perspective. We propose that human dance evolved from ordinary (non-communicative) movements to communicate socially relevant information accurately. The need for accurate social signaling may have accompanied increases in group size and population density. Because of its complexity in production and display, dance may have evolved as a vehicle for expressing social and cultural information. Mating-related qualities and motives may have been the predominant information derived from individual dance movements, whereas group dance offers the opportunity for the exchange of socially relevant content, for coordinating actions among group members, for signaling coalitional strength, and for stabilizing group structures. We conclude that, despite the cultural diversity in dance movements and contexts, the primary communicative functions of dance may be the same across societies.
  • Gordon, R. L., Ravignani, A., Hyland Bruno, J., Robinson, C. M., Scartozzi, A., Embalabala, R., Niarchou, M., 23andMe Research Team, Cox, N. J., & Creanza, N. (2021). Linking the genomic signatures of human beat synchronization and learned song in birds. Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, 376: 20200329. doi:10.1098/rstb.2020.0329.

    Abstract

    The development of rhythmicity is foundational to communicative and social behaviours in humans and many other species, and mechanisms of synchrony could be conserved across species. The goal of the current paper is to explore evolutionary hypotheses linking vocal learning and beat synchronization through genomic approaches, testing the prediction that genetic underpinnings of birdsong also contribute to the aetiology of human interactions with musical beat structure. We combined state-of-the-art-genomic datasets that account for underlying polygenicity of these traits: birdsong genome-wide transcriptomics linked to singing in zebra finches, and a human genome-wide association study of beat synchronization. Results of competitive gene set analysis revealed that the genetic architecture of human beat synchronization is significantly enriched for birdsong genes expressed in songbird Area X (a key nucleus for vocal learning, and homologous to human basal ganglia). These findings complement ethological and neural evidence of the relationship between vocal learning and beat synchronization, supporting a framework of some degree of common genomic substrates underlying rhythm-related behaviours in two clades, humans and songbirds (the largest evolutionary radiation of vocal learners). Future cross-species approaches investigating the genetic underpinnings of beat synchronization in a broad evolutionary context are discussed.

    Additional information

    analysis scripts and variables
  • Greenfield, M. D., Honing, H., Kotz, S. A., & Ravignani, A. (Eds.). (2021). Synchrony and rhythm interaction: From the brain to behavioural ecology [Special Issue]. Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, 376.
  • Greenfield, M. D., Honing, H., Kotz, S. A., & Ravignani, A. (2021). Synchrony and rhythm interaction: From the brain to behavioural ecology. Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, 376: 20200324. doi:10.1098/rstb.2020.0324.

    Abstract

    This theme issue assembles current studies that ask how and why precise synchronization and related forms of rhythm interaction are expressed in a wide range of behaviour. The studies cover human activity, with an emphasis on music, and social behaviour, reproduction and communication in non-human animals. In most cases, the temporally aligned rhythms have short—from several seconds down to a fraction of a second—periods and are regulated by central nervous system pacemakers, but interactions involving rhythms that are 24 h or longer and originate in biological clocks also occur. Across this spectrum of activities, species and time scales, empirical work and modelling suggest that synchrony arises from a limited number of coupled-oscillator mechanisms with which individuals mutually entrain. Phylogenetic distribution of these common mechanisms points towards convergent evolution. Studies of animal communication indicate that many synchronous interactions between the signals of neighbouring individuals are specifically favoured by selection. However, synchronous displays are often emergent properties of entrainment between signalling individuals, and in some situations, the very signallers who produce a display might not gain any benefit from the collective timing of their production.
  • De Gregorio, C., Valente, D., Raimondi, T., Torti, V., Miaretsoa, L., Friard, O., Giacoma, C., Ravignani, A., & Gamba, M. (2021). Categorical rhythms in a singing primate. Current Biology, 31, R1363-R1380. doi:10.1016/j.cub.2021.09.032.

    Abstract

    What are the origins of musical rhythm? One approach to the biology and evolution of music consists in finding common musical traits across species. These similarities allow biomusicologists to infer when and how musical traits appeared in our species1
    . A parallel approach to the biology and evolution of music focuses on finding statistical universals in human music2
    . These include rhythmic features that appear above chance across musical cultures. One such universal is the production of categorical rhythms3
    , defined as those where temporal intervals between note onsets are distributed categorically rather than uniformly2
    ,4
    ,5
    . Prominent rhythm categories include those with intervals related by small integer ratios, such as 1:1 (isochrony) and 1:2, which translates as some notes being twice as long as their adjacent ones. In humans, universals are often defined in relation to the beat, a top-down cognitive process of inferring a temporal regularity from a complex musical scene1
    . Without assuming the presence of the beat in other animals, one can still investigate its downstream products, namely rhythmic categories with small integer ratios detected in recorded signals. Here we combine the comparative and statistical universals approaches, testing the hypothesis that rhythmic categories and small integer ratios should appear in species showing coordinated group singing3
    . We find that a lemur species displays, in its coordinated songs, the isochronous and 1:2 rhythm categories seen in human music, showing that such categories are not, among mammals, unique to humans3

    Additional information

    supplemental information
  • Hoeksema, N., Verga, L., Mengede, J., Van Roessel, C., Villanueva, S., Salazar-Casals, A., Rubio-Garcia, A., Curcic-Blake, B., Vernes, S. C., & Ravignani, A. (2021). Neuroanatomy of the grey seal brain: Bringing pinnipeds into the neurobiological study of vocal learning. Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, 376: 20200252. doi:10.1098/rstb.2020.0252.

    Abstract

    Comparative studies of vocal learning and vocal non-learning animals can increase our understanding of the neurobiology and evolution of vocal learning and human speech. Mammalian vocal learning is understudied: most research has either focused on vocal learning in songbirds or its absence in non-human primates. Here we focus on a highly promising model species for the neurobiology of vocal learning: grey seals. We provide a neuroanatomical atlas (based on dissected brain slices and magnetic resonance images), a labelled MRI template, a 3D model with volumetric measurements of brain regions, and histological cortical stainings. Four main features of the grey seal brain stand out. (1) It is relatively big and highly convoluted. (2) It hosts a relatively large temporal lobe and cerebellum, structures which could support developed timing abilities and acoustic processing. (3) The cortex is similar to humans in thickness and shows the expected six-layered mammalian structure. (4) Expression of FoxP2 - a gene involved in vocal learning and spoken language - is present in deeper layers of the cortex. Our results could facilitate future studies targeting the neural and genetic underpinnings of mammalian vocal learning, thus bridging the research gap from songbirds to humans and non-human primates.Competing Interest StatementThe authors have declared no competing interest.
  • Ravignani, A. (2021). Isochrony, vocal learning and the acquisition of rhythm and melody. Behavioral and Brain Sciences, 44: e88. doi:10.1017/S0140525X20001478.

    Abstract

    A cross-species perspective can extend and provide testable predictions for Savage et al.’s
    framework. Rhythm and melody, I argue, could bootstrap each other in the evolution of
    musicality. Isochrony may function as a temporal grid to support rehearsing and learning
    modulated, pitched vocalizations. Once this melodic plasticity is acquired, focus can shift back to refining rhythm processing and beat induction.
  • Ravignani, A., & De Boer, B. (2021). Joint origins of speech and music: Testing evolutionary hypotheses on modern humans. Semiotica, 239, 169-176. doi:10.1515/sem-2019-0048.

    Abstract

    How music and speech evolved is a mystery. Several hypotheses on their
    origins, including one on their joint origins, have been put forward but rarely
    tested. Here we report and comment on the first experiment testing the hypothesis
    that speech and music bifurcated from a common system. We highlight strengths
    of the reported experiment, point out its relatedness to animal work, and suggest
    three alternative interpretations of its results. We conclude by sketching a future
    empirical programme extending this work.
  • de Reus, K., Soma, M., Anichini, M., Gamba, M., de Heer Kloots, M., Lense, M., Bruno, J. H., Trainor, L., & Ravignani, A. (2021). Rhythm in dyadic interactions. Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, 376: 20200337. doi:10.1098/rstb.2020.0337.

    Abstract

    This review paper discusses rhythmic dyadic interactions in social and sexual contexts. We report rhythmic interactions during communication within dyads, as found in humans, non-human primates, non-primate mammals, birds, anurans and insects. Based on the patterns observed, we infer adaptive explanations for the observed rhythm interactions and identify knowledge gaps. Across species, the social environment during ontogeny is a key factor in shaping adult signal repertoires and timing mechanisms used to regulate interactions. The degree of temporal coordination is influenced by the dynamic and strength of the dyadic interaction. Most studies of temporal structure in interactive signals mainly focus on one modality (acoustic and visual); we suggest more work should be performed on multimodal signals. Multidisciplinary approaches combining cognitive science, ethology and ecology should shed more light on the exact timing mechanisms involved. Taken together, rhythmic signalling behaviours are widespread and critical in regulating social interactions across taxa.
  • Torres Borda, L., Jadoul, Y., Rasilo, H., Salazar-Casals, A., & Ravignani, A. (2021). Vocal plasticity in harbour seal pups. Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, 376(1840): 20200456. doi:10.1098/rstb.2020.0456.

    Abstract

    Vocal plasticity can occur in response to environmental and biological factors, including conspecifics' vocalizations and noise. Pinnipeds are one of the few mammalian groups capable of vocal learning, and are therefore relevant to understanding the evolution of vocal plasticity in humans and other animals. Here, we investigate the vocal plasticity of harbour seals (Phoca vitulina), a species with vocal learning abilities observed in adulthood but not puppyhood. To evaluate early mammalian vocal development, we tested 1–3 weeks-old seal pups. We tailored noise playbacks to this species and age to induce seal pups to shift their fundamental frequency (f0), rather than adapt call amplitude or temporal characteristics. We exposed individual pups to low- and high-intensity bandpass-filtered noise, which spanned—and masked—their typical range of f0; simultaneously, we recorded pups' spontaneous calls. Unlike most mammals, pups modified their vocalizations by lowering their f0 in response to increased noise. This modulation was precise and adapted to the particular experimental manipulation of the noise condition. In addition, higher levels of noise induced less dispersion around the mean f0, suggesting that pups may have actively focused their phonatory efforts to target lower frequencies. Noise did not seem to affect call amplitude. However, one seal showed two characteristics of the Lombard effect known for human speech in noise: significant increase in call amplitude and flattening of spectral tilt. Our relatively low noise levels may have favoured f0 modulation while inhibiting amplitude adjustments. This lowering of f0 is unusual, as most animals commonly display no such f0 shift. Our data represent a relatively rare case in mammalian neonates, and have implications for the evolution of vocal plasticity and vocal learning across species, including humans.

    Additional information

    supplement
  • Varola*, M., Verga*, L., Sroka, M., Villanueva, S., Charrier, I., & Ravignani, A. (2021). Can harbor seals (Phoca vitulina) discriminate familiar conspecific calls after long periods of separation? PeerJ, 9: e12431. doi:10.7717/peerj.12431.

    Abstract

    * - indicates joint first authorship -
    The ability to discriminate between familiar and unfamiliar calls may play a key role in pinnipeds’ communication and survival, as in the case of mother-pup interactions. Vocal discrimination abilities have been suggested to be more developed in pinniped species with the highest selective pressure such as the otariids; yet, in some group-living phocids, such as harbor seals (Phoca vitulina), mothers are also able to recognize their pup’s voice. Conspecifics’ vocal recognition in pups has never been investigated; however, the repeated interaction occurring between pups within the breeding season suggests that long-term vocal discrimination may occur. Here we explored this hypothesis by presenting three rehabilitated seal pups with playbacks of vocalizations from unfamiliar or familiar pups. It is uncommon for seals to come into rehabilitation for a second time in their lifespan, and this study took advantage of these rare cases. A simple visual inspection of the data plots seemed to show more reactions, and of longer duration, in response to familiar as compared to unfamiliar playbacks in two out of three pups. However, statistical analyses revealed no significant difference between the experimental conditions. We also found no significant asymmetry in orientation (left vs. right) towards familiar and unfamiliar sounds. While statistics do not support the hypothesis of an established ability to discriminate familiar vocalizations from unfamiliar ones in harbor seal pups, further investigations with a larger sample size are needed to confirm or refute this hypothesis.

    Additional information

    dataset
  • Verga, L., & Ravignani, A. (2021). Strange seal sounds: Claps, slaps, and multimodal pinniped rhythms. Frontiers in Ecology and Evolution, 9: 644497. doi:10.3389/fevo.2021.644497.
  • Verhoef, T., & Ravignani, A. (2021). Melodic universals emerge or are sustained through cultural evolution. Frontiers in Psychology, 12: 668300. doi:10.3389/fpsyg.2021.668300.

    Abstract

    To understand why music is structured the way it is, we need an explanation that accounts for both the universality and variability found in musical traditions. Here we test whether statistical universals that have been identified for melodic structures in music can emerge as a result of cultural adaptation to human biases through iterated learning. We use data from an experiment in which artificial whistled systems, where sounds were produced with a slide whistle, were learned by human participants and transmitted multiple times from person to person. These sets of whistled signals needed to be memorized and recalled and the reproductions of one participant were used as the input set for the next. We tested for the emergence of seven different melodic features, such as discrete pitches, motivic patterns, or phrase repetition, and found some evidence for the presence of most of these statistical universals. We interpret this as promising evidence that, similarly to rhythmic universals, iterated learning experiments can also unearth melodic statistical universals. More, ideally cross-cultural, experiments are nonetheless needed. Simulating the cultural transmission of artificial proto-musical systems can help unravel the origins of universal tendencies in musical structures.
  • Anichini, M., De Heer Kloots, M., & Ravignani, A. (2020). Interactive rhythms in the wild, in the brain, and in silico. Canadian Journal of Experimental Psychology, 74(3), 170-175. doi:10.1037/cep0000224.

    Abstract

    There are some historical divisions in methods, rationales, and purposes between
    studies on comparative cognition and behavioural ecology. In turn, the interaction between
    these two branches and studies from mathematics, computation and neuroscience is not
    usual. In this short piece, we attempt to build bridges among these disciplines. We present a
    series of interconnected vignettes meant to illustrate how a more interdisciplinary approach
    looks like when successful, and its advantages. Concretely, we focus on a recent topic,
    namely animal rhythms in interaction, studied under different approaches. We showcase 5
    research efforts, which we believe successfully link 5 particular Scientific areas of rhythm
    research conceptualized as: Social neuroscience, Detailed rhythmic quantification,
    Ontogeny, Computational approaches and Spontaneous interactions. Our suggestions will
    hopefully spur a ‘Comparative rhythms in interaction’ field, which can integrate and
    capitalize on knowledge from zoology, comparative psychology, neuroscience, and
    computation.
  • De Boer, B., Thompson, B., Ravignani, A., & Boeckx, C. (2020). Analysis of mutation and fixation for language. In A. Ravignani, C. Barbieri, M. Flaherty, Y. Jadoul, E. Lattenkamp, H. Little, M. Martins, K. Mudd, & T. Verhoef (Eds.), The Evolution of Language: Proceedings of the 13th International Conference (Evolang13) (pp. 56-58). Nijmegen: The Evolution of Language Conferences.
  • De Boer, B., Thompson, B., Ravignani, A., & Boeckx, C. (2020). Evolutionary dynamics do not motivate a single-mutant theory of human language. Scientific Reports, 10: 451. doi:10.1038/s41598-019-57235-8.

    Abstract

    One of the most controversial hypotheses in cognitive science is the Chomskyan evolutionary conjecture that language arose instantaneously in humans through a single mutation. Here we analyze the evolutionary dynamics implied by this hypothesis, which has never been formalized before. The hypothesis supposes the emergence and fixation of a single mutant (capable of the syntactic operation Merge) during a narrow historical window as a result of frequency-independent selection under a huge fitness advantage in a population of an effective size no larger than ~15 000 individuals. We examine this proposal by combining diffusion analysis and extreme value theory to derive a probabilistic formulation of its dynamics. We find that although a macro-mutation is much more likely to go to fixation if it occurs, it is much more unlikely a priori than multiple mutations with smaller fitness effects. The most likely scenario is therefore one where a medium number of mutations with medium fitness effects accumulate. This precise analysis of the probability of mutations occurring and going to fixation has not been done previously in the context of the evolution of language. Our results cast doubt on any suggestion that evolutionary reasoning provides an independent rationale for a single-mutant theory of language.

    Additional information

    Supplementary material
  • Garcia, M., & Ravignani, A. (2020). Acoustic allometry and vocal learning in mammals. Biology Letters, 16: 20200081. doi:10.1098/rsbl.2020.0081.

    Abstract

    Acoustic allometry is the study of how animal vocalisations reflect their body size. A key aim of this research is to identify outliers to acoustic allometry principles and pinpoint the evolutionary origins of such outliers. A parallel strand of research investigates species capable of vocal learning, the experience-driven ability to produce novel vocal signals through imitation or modification of existing vocalisations. Modification of vocalizations is a common feature found when studying both acoustic allometry and vocal learning. Yet, these two fields have only been investigated separately to date. Here, we review and connect acoustic allometry and vocal learning across mammalian clades, combining perspectives from bioacoustics, anatomy and evolutionary biology. Based on this, we hypothesize that, as a precursor to vocal learning, some species might have evolved the capacity for volitional vocal modulation via sexual selection for ‘dishonest’ signalling. We provide preliminary support for our hypothesis by showing significant associations between allometric deviation and vocal learning in a dataset of 164 mammals. Our work offers a testable framework for future empirical research linking allometric principles with the evolution of vocal learning.
  • Garcia, M., Theunissen, F., Sèbe, F., Clavel, J., Ravignani, A., Marin-Cudraz, T., Fuchs, J., & Mathevon, N. (2020). Evolution of communication signals and information during species radiation. Nature Communications, 11: 4970. doi:10.1038/s41467-020-18772-3.

    Abstract

    Communicating species identity is a key component of many animal signals. However, whether selection for species recognition systematically increases signal diversity during clade radiation remains debated. Here we show that in woodpecker drumming, a rhythmic signal used during mating and territorial defense, the amount of species identity information encoded remained stable during woodpeckers’ radiation. Acoustic analyses and evolutionary reconstructions show interchange among six main drumming types despite strong phylogenetic contingencies, suggesting evolutionary tinkering of drumming structure within a constrained acoustic space. Playback experiments and quantification of species discriminability demonstrate sufficient signal differentiation to support species recognition in local communities. Finally, we only find character displacement in the rare cases where sympatric species are also closely related. Overall, our results illustrate how historical contingencies and ecological interactions can promote conservatism in signals during a clade radiation without impairing the effectiveness of information transfer relevant to inter-specific discrimination.
  • Geambasu, A., Toron, L., Ravignani, A., & Levelt, C. C. (2020). Rhythmic recursion? Human sensitivity to a Lindenmayer grammar with self-similar structure in a musical task. Music & Science. doi:10.1177%2F2059204320946615.

    Abstract

    Processing of recursion has been proposed as the foundation of human linguistic ability. Yet this ability may be shared with other domains, such as the musical or rhythmic domain. Lindenmayer grammars (L-systems) have been proposed as a recursive grammar for use in artificial grammar experiments to test recursive processing abilities, and previous work had shown that participants are able to learn such a grammar using linguistic stimuli (syllables). In the present work, we used two experimental paradigms (a yes/no task and a two-alternative forced choice) to test whether adult participants are able to learn a recursive Lindenmayer grammar composed of drum sounds. After a brief exposure phase, we found that participants at the group level were sensitive to the exposure grammar and capable of distinguishing the grammatical and ungrammatical test strings above chance level in both tasks. While we found evidence of participants’ sensitivity to a very complex L-system grammar in a non-linguistic, potentially musical domain, the results were not robust. We discuss the discrepancy within our results and with the previous literature using L-systems in the linguistic domain. Furthermore, we propose directions for future music cognition research using L-system grammars.
  • De Heer Kloots, M., Carlson, D., Garcia, M., Kotz, S., Lowry, A., Poli-Nardi, L., de Reus, K., Rubio-García, A., Sroka, M., Varola, M., & Ravignani, A. (2020). Rhythmic perception, production and interactivity in harbour and grey seals. In A. Ravignani, C. Barbieri, M. Flaherty, Y. Jadoul, E. Lattenkamp, H. Little, M. Martins, K. Mudd, & T. Verhoef (Eds.), The Evolution of Language: Proceedings of the 13th International Conference (Evolang13) (pp. 59-62). Nijmegen: The Evolution of Language Conferences.
  • Heinrich, T., Ravignani, A., & Hanke, F. H. (2020). Visual timing abilities of a harbour seal (Phoca vitulina) and a South African fur seal (Arctocephalus pusillus pusillus) for sub- and supra-second time intervals. Animal Cognition, 23(5), 851-859. doi:10.1007/s10071-020-01390-3.

    Abstract

    Timing is an essential parameter influencing many behaviours. A previous study demonstrated a high sensitivity of a phocid, the harbour seal (Phoca vitulina), in discriminating time intervals. In the present study, we compared the harbour seal’s timing abilities with the timing abilities of an otariid, the South African fur seal (Arctocephalus pusillus pusillus). This comparison seemed essential as phocids and otariids differ in many respects and might, thus, also differ regarding their timing abilities. We determined time difference thresholds for sub- and suprasecond time intervals marked by a white circle on a black background displayed for a specific time interval on a monitor using a staircase method. Contrary to our expectation, the timing abilities of the fur seal and the harbour seal were comparable. Over a broad range of time intervals, 0.8–7 s in the fur seal and 0.8–30 s in the harbour seal, the difference thresholds followed Weber’s law. In this range, both animals could discriminate time intervals differing only by 12 % and 14 % on average. Timing might, thus be a fundamental cue for pinnipeds in general to be used in various contexts, thereby complementing information provided by classical sensory systems. Future studies will help to clarify if timing is indeed involved in foraging decisions or the estimation of travel speed or distance.

    Additional information

    supplementary material
  • Hoeksema, N., Villanueva, S., Mengede, J., Salazar-Casals, A., Rubio-García, A., Curcic-Blake, B., Vernes, S. C., & Ravignani, A. (2020). Neuroanatomy of the grey seal brain: Bringing pinnipeds into the neurobiological study of vocal learning. In A. Ravignani, C. Barbieri, M. Flaherty, Y. Jadoul, E. Lattenkamp, H. Little, M. Martins, K. Mudd, & T. Verhoef (Eds.), The Evolution of Language: Proceedings of the 13th International Conference (Evolang13) (pp. 162-164). Nijmegen: The Evolution of Language Conferences.
  • Jacoby, N., Margulis, E. H., Clayton, M., Hannon, E., Honing, H., Iversen, J., Klein, T. R., Mehr, S. A., Pearson, L., Peretz, I., Perlman, M., Polak, R., Ravignani, A., Savage, P. E., Steingo, G., Stevens, C. J., Trainor, L., Trehub, S., Veal, M., & Wald-Fuhrmann, M. (2020). Cross-cultural work in music cognition: Challenges, insights, and recommendations. Music Perception, 37(3), 185-195. doi:10.1525/mp.2020.37.3.185.

    Abstract

    Many foundational questions in the psychology of music require cross-cultural approaches, yet the vast majority of work in the field to date has been conducted with Western participants and Western music. For cross-cultural research to thrive, it will require collaboration between people from different disciplinary backgrounds, as well as strategies for overcoming differences in assumptions, methods, and terminology. This position paper surveys the current state of the field and offers a number of concrete recommendations focused on issues involving ethics, empirical methods, and definitions of “music” and “culture.”
  • Ravignani, A., & Kotz, S. (2020). Breathing, voice and synchronized movement. Proceedings of the National Academy of Sciences of the United States of America, 117(38), 23223-23224. doi:10.1073/pnas.2011402117.
  • Ravignani, A., Barbieri, C., Flaherty, M., Jadoul, Y., Lattenkamp, E. Z., Little, H., Martins, M., Mudd, K., & Verhoef, T. (Eds.). (2020). The Evolution of Language: Proceedings of the 13th International Conference (Evolang13). Nijmegen: The Evolution of Language Conferences. doi:10.17617/2.3190925.
  • de Reus, K., Carlson, D., Jadoul, Y., Lowry, A., Gross, S., Garcia, M., Salazar-Casals, A., Rubio-García, A., Haas, C. E., De Boer, B., & Ravignani, A. (2020). Relationships between vocal ontogeny and vocal tract anatomy in harbour seals (Phoca vitulina). In A. Ravignani, C. Barbieri, M. Flaherty, Y. Jadoul, E. Lattenkamp, H. Little, M. Martins, K. Mudd, & T. Verhoef (Eds.), The Evolution of Language: Proceedings of the 13th International Conference (Evolang13) (pp. 63-66). Nijmegen: The Evolution of Language Conferences.
  • Wilson, B., Spierings, M., Ravignani, A., Mueller, J. L., Mintz, T. H., Wijnen, F., Van der Kant, A., Smith, K., & Rey, A. (2020). Non‐adjacent dependency learning in humans and other animals. Topics in Cognitive Science, 12(3), 843-858. doi:10.1111/tops.12381.

    Abstract

    Learning and processing natural language requires the ability to track syntactic relationships between words and phrases in a sentence, which are often separated by intervening material. These nonadjacent dependencies can be studied using artificial grammar learning paradigms and structured sequence processing tasks. These approaches have been used to demonstrate that human adults, infants and some nonhuman animals are able to detect and learn dependencies between nonadjacent elements within a sequence. However, learning nonadjacent dependencies appears to be more cognitively demanding than detecting dependencies between adjacent elements, and only occurs in certain circumstances. In this review, we discuss different types of nonadjacent dependencies in language and in artificial grammar learning experiments, and how these differences might impact learning. We summarize different types of perceptual cues that facilitate learning, by highlighting the relationship between dependent elements bringing them closer together either physically, attentionally, or perceptually. Finally, we review artificial grammar learning experiments in human adults, infants, and nonhuman animals, and discuss how similarities and differences observed across these groups can provide insights into how language is learned across development and how these language‐related abilities might have evolved.
  • Lameira, A. R., Eerola, T., & Ravignani, A. (2019). Coupled whole-body rhythmic entrainment between two chimpanzees. Scientific Reports, 9: 18914. doi:10.1038/s41598-019-55360-y.

    Abstract

    Dance is an icon of human expression. Despite astounding diversity around the world’s cultures and dazzling abundance of reminiscent animal systems, the evolution of dance in the human clade remains obscure. Dance requires individuals to interactively synchronize their whole-body tempo to their partner’s, with near-perfect precision. This capacity is motorically-heavy, engaging multiple neural circuitries, but also dependent on an acute socio-emotional bond between partners. Hitherto, these factors helped explain why no dance forms were present amongst nonhuman primates. Critically, evidence for conjoined full-body rhythmic entrainment in great apes that could help reconstruct possible proto-stages of human dance is still lacking. Here, we report an endogenously-effected case of ritualized dance-like behaviour between two captive chimpanzees – synchronized bipedalism. We submitted video recordings to rigorous time-series analysis and circular statistics. We found that individual step tempo was within the genus’ range of “solo” bipedalism. Between-individual analyses, however, revealed that synchronisation between individuals was non-random, predictable, phase concordant, maintained with instantaneous centi-second precision and jointly regulated, with individuals also taking turns as “pace-makers”. No function was apparent besides the behaviour’s putative positive social affiliation. Our analyses show a first case of spontaneous whole-body entrainment between two ape peers, thus providing tentative empirical evidence for phylogenies of human dance. Human proto-dance, we argue, may have been rooted in mechanisms of social cohesion among small groups that might have granted stress-releasing benefits via gait-synchrony and mutual-touch. An external sound/musical beat may have been initially uninvolved. We discuss dance evolution as driven by ecologically-, socially- and/or culturally-imposed “captivity”.

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    Supplementary Information
  • Larsson, M., Richter, J., & Ravignani, A. (2019). Bipedal steps in the development of rhythmic behavior in humans. Music & Science, 2, 1-14. doi:10.1177/2059204319892617.

    Abstract

    We contrast two related hypotheses of the evolution of dance: H1: Maternal bipedal walking influenced the fetal experience of sound and associated movement patterns; H2: The human transition to bipedal gait produced more isochronous/predictable locomotion sound resulting in early music-like behavior associated with the acoustic advantages conferred by moving bipedally in pace. The cadence of walking is around 120 beats per minute, similar to the tempo of dance and music. Human walking displays long-term constancies. Dyads often subconsciously synchronize steps. The major amplitude component of the step is a distinctly produced beat. Human locomotion influences, and interacts with, emotions, and passive listening to music activates brain motor areas. Across dance-genres the footwork is most often performed in time to the musical beat. Brain development is largely shaped by early sensory experience, with hearing developed from week 18 of gestation. Newborns reacts to sounds, melodies, and rhythmic poems to which they have been exposed in utero. If the sound and vibrations produced by footfalls of a walking mother are transmitted to the fetus in coordination with the cadence of the motion, a connection between isochronous sound and rhythmical movement may be developed. Rhythmical sounds of the human mother locomotion differ substantially from that of nonhuman primates, while the maternal heartbeat heard is likely to have a similar isochronous character across primates, suggesting a relatively more influential role of footfall in the development of rhythmic/musical abilities in humans. Associations of gait, music, and dance are numerous. The apparent absence of musical and rhythmic abilities in nonhuman primates, which display little bipedal locomotion, corroborates that bipedal gait may be linked to the development of rhythmic abilities in humans. Bipedal stimuli in utero may primarily boost the ontogenetic development. The acoustical advantage hypothesis proposes a mechanism in the phylogenetic development.
  • Ravignani, A. (2019). [Review of the book Animal beauty: On the evolution of bological aesthetics by C. Nüsslein-Volhard]. Animal Behaviour, 155, 171-172. doi:10.1016/j.anbehav.2019.07.005.
  • Ravignani, A. (2019). [Review of the book The origins of musicality ed. by H. Honing]. Perception, 48(1), 102-105. doi:10.1177/0301006618817430.
  • Ravignani, A. (2019). Humans and other musical animals [Review of the book The evolving animal orchestra: In search of what makes us musical by Henkjan Honing]. Current Biology, 29(8), R271-R273. doi:10.1016/j.cub.2019.03.013.
  • Ravignani, A., & de Reus, K. (2019). Modelling animal interactive rhythms in communication. Evolutionary Bioinformatics, 15, 1-14. doi:10.1177/1176934318823558.

    Abstract

    Time is one crucial dimension conveying information in animal communication. Evolution has shaped animals’ nervous systems to produce signals with temporal properties fitting their socio-ecological niches. Many quantitative models of mechanisms underlying rhythmic behaviour exist, spanning insects, crustaceans, birds, amphibians, and mammals. However, these computational and mathematical models are often presented in isolation. Here, we provide an overview of the main mathematical models employed in the study of animal rhythmic communication among conspecifics. After presenting basic definitions and mathematical formalisms, we discuss each individual model. These computational models are then compared using simulated data to uncover similarities and key differences in the underlying mechanisms found across species. Our review of the empirical literature is admittedly limited. We stress the need of using comparative computer simulations – both before and after animal experiments – to better understand animal timing in interaction. We hope this article will serve as a potential first step towards a common computational framework to describe temporal interactions in animals, including humans.

    Additional information

    Supplemental material files
  • Ravignani, A., Verga, L., & Greenfield, M. D. (2019). Interactive rhythms across species: The evolutionary biology of animal chorusing and turn-taking. Annals of the New York Academy of Sciences, 1453(1), 12-21. doi:10.1111/nyas.14230.

    Abstract

    The study of human language is progressively moving toward comparative and interactive frameworks, extending the concept of turn‐taking to animal communication. While such an endeavor will help us understand the interactive origins of language, any theoretical account for cross‐species turn‐taking should consider three key points. First, animal turn‐taking must incorporate biological studies on animal chorusing, namely how different species coordinate their signals over time. Second, while concepts employed in human communication and turn‐taking, such as intentionality, are still debated in animal behavior, lower level mechanisms with clear neurobiological bases can explain much of animal interactive behavior. Third, social behavior, interactivity, and cooperation can be orthogonal, and the alternation of animal signals need not be cooperative. Considering turn‐taking a subset of chorusing in the rhythmic dimension may avoid overinterpretation and enhance the comparability of future empirical work.
  • Ravignani, A. (2019). Everything you always wanted to know about sexual selection in 129 pages [Review of the book Sexual selection: A very short introduction by M. Zuk and L. W. Simmons]. Journal of Mammalogy, 100(6), 2004-2005. doi:10.1093/jmammal/gyz168.
  • Ravignani, A., & Gamba, M. (2019). Evolving musicality [Review of the book The evolving animal orchestra: In search of what makes us musical by Henkjan Honing]. Trends in Ecology and Evolution, 34(7), 583-584. doi:10.1016/j.tree.2019.04.016.
  • Ravignani, A., Kello, C. T., de Reus, K., Kotz, S. A., Dalla Bella, S., Mendez-Arostegui, M., Rapado-Tamarit, B., Rubio-Garcia, A., & de Boer, B. (2019). Ontogeny of vocal rhythms in harbor seal pups: An exploratory study. Current Zoology, 65(1), 107-120. doi:10.1093/cz/zoy055.

    Abstract

    Puppyhood is a very active social and vocal period in a harbor seal's life Phoca vitulina. An important feature of vocalizations is their temporal and rhythmic structure, and understanding vocal timing and rhythms in harbor seals is critical to a cross-species hypothesis in evolutionary neuroscience that links vocal learning, rhythm perception, and synchronization. This study utilized analytical techniques that may best capture rhythmic structure in pup vocalizations with the goal of examining whether (1) harbor seal pups show rhythmic structure in their calls and (2) rhythms evolve over time. Calls of 3 wild-born seal pups were recorded daily over the course of 1-3 weeks; 3 temporal features were analyzed using 3 complementary techniques. We identified temporal and rhythmic structure in pup calls across different time windows. The calls of harbor seal pups exhibit some degree of temporal and rhythmic organization, which evolves over puppyhood and resembles that of other species' interactive communication. We suggest next steps for investigating call structure in harbor seal pups and propose comparative hypotheses to test in other pinniped species.
  • Ravignani, A., Filippi, P., & Fitch, W. T. (2019). Perceptual tuning influences rule generalization: Testing humans with monkey-tailored stimuli. i-Perception, 10(2), 1-5. doi:10.1177/2041669519846135.

    Abstract

    Comparative research investigating how nonhuman animals generalize patterns of auditory stimuli often uses sequences of human speech syllables and reports limited generalization abilities in animals. Here, we reverse this logic, testing humans with stimulus sequences tailored to squirrel monkeys. When test stimuli are familiar (human voices), humans succeed in two types of generalization. However, when the same structural rule is instantiated over unfamiliar but perceivable sounds within squirrel monkeys’ optimal hearing frequency range, human participants master only one type of generalization. These findings have methodological implications for the design of comparative experiments, which should be fair towards all tested species’ proclivities and limitations.

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    Supplemental material files
  • Ravignani, A. (2019). Singing seals imitate human speech. Journal of Experimental Biology, 222: jeb208447. doi:10.1242/jeb.208447.
  • Ravignani, A., Chiandetti, C., & Kotz, S. (2019). Rhythm and music in animal signals. In J. Choe (Ed.), Encyclopedia of Animal Behavior (vol. 1) (2nd ed., pp. 615-622). Amsterdam: Elsevier.
  • Ravignani, A. (2019). Rhythm and synchrony in animal movement and communication. Current Zoology, 65(1), 77-81. doi:10.1093/cz/zoy087.

    Abstract

    Animal communication and motoric behavior develop over time. Often, this temporal dimension has communicative relevance and is organized according to structural patterns. In other words, time is a crucial dimension for rhythm and synchrony in animal movement and communication. Rhythm is defined as temporal structure at a second-millisecond time scale (Kotz et al. 2018). Synchrony is defined as precise co-occurrence of 2 behaviors in time (Ravignani 2017).

    Rhythm, synchrony, and other forms of temporal interaction are taking center stage in animal behavior and communication. Several critical questions include, among others: what species show which rhythmic predispositions? How does a species’ sensitivity for, or proclivity towards, rhythm arise? What are the species-specific functions of rhythm and synchrony, and are there functional trends across species? How did similar or different rhythmic behaviors evolved in different species? This Special Column aims at collecting and contrasting research from different species, perceptual modalities, and empirical methods. The focus is on timing, rhythm and synchrony in the second-millisecond range.

    Three main approaches are commonly adopted to study animal rhythms, with a focus on: 1) spontaneous individual rhythm production, 2) group rhythms, or 3) synchronization experiments. I concisely introduce them below (see also Kotz et al. 2018; Ravignani et al. 2018).
  • Ravignani, A., Dalla Bella, S., Falk, S., Kello, C. T., Noriega, F., & Kotz, S. A. (2019). Rhythm in speech and animal vocalizations: A cross‐species perspective. Annals of the New York Academy of Sciences, 1453(1), 79-98. doi:10.1111/nyas.14166.

    Abstract

    Why does human speech have rhythm? As we cannot travel back in time to witness how speech developed its rhythmic properties and why humans have the cognitive skills to process them, we rely on alternative methods to find out. One powerful tool is the comparative approach: studying the presence or absence of cognitive/behavioral traits in other species to determine which traits are shared between species and which are recent human inventions. Vocalizations of many species exhibit temporal structure, but little is known about how these rhythmic structures evolved, are perceived and produced, their biological and developmental bases, and communicative functions. We review the literature on rhythm in speech and animal vocalizations as a first step toward understanding similarities and differences across species. We extend this review to quantitative techniques that are useful for computing rhythmic structure in acoustic sequences and hence facilitate cross‐species research. We report links between vocal perception and motor coordination and the differentiation of rhythm based on hierarchical temporal structure. While still far from a complete cross‐species perspective of speech rhythm, our review puts some pieces of the puzzle together.
  • Ravignani, A. (2019). Seeking shared ground in space. Science, 366(6466), 696. doi:10.1126/science.aay6955.
  • Ravignani, A. (2019). Timing of antisynchronous calling: A case study in a harbor seal pup (Phoca vitulina). Journal of Comparative Psychology, 133(2), 272-277. doi:10.1037/com0000160.

    Abstract

    Alternative mathematical models predict differences in how animals adjust the timing of their calls. Differences can be measured as the effect of the timing of a conspecific call on the rate and period of calling of a focal animal, and the lag between the two. Here, I test these alternative hypotheses by tapping into harbor seals’ (Phoca vitulina) mechanisms for spontaneous timing. Both socioecology and vocal behavior of harbor seals make them an interesting model species to study call rhythm and timing. Here, a wild-born seal pup was tested in controlled laboratory conditions. Based on previous recordings of her vocalizations and those of others, I designed playback experiments adapted to that specific animal. The call onsets of the animal were measured as a function of tempo, rhythmic regularity, and spectral properties of the playbacks. The pup adapted the timing of her calls in response to conspecifics’ calls. Rather than responding at a fixed time delay, the pup adjusted her calls’ onset to occur at a fraction of the playback tempo, showing a relative-phase antisynchrony. Experimental results were confirmed via computational modeling. This case study lends preliminary support to a classic mathematical model of animal behavior—Hamilton’s selfish herd—in the acoustic domain.
  • Ravignani, A. (2019). Understanding mammals, hands-on [Review of the book Mammalogy techniques lab manual by J. M. Ryan]. Journal of Mammalogy, 100(5), 1695-1696. doi:10.1093/jmammal/gyz132.
  • Reber, S. A., Šlipogor, V., Oh, J., Ravignani, A., Hoeschele, M., Bugnyar, T., & Fitch, W. T. (2019). Common marmosets are sensitive to simple dependencies at variable distances in an artificial grammar. Evolution and Human Behavior, 40(2), 214-221. doi:10.1016/j.evolhumbehav.2018.11.006.

    Abstract

    Recognizing that two elements within a sequence of variable length depend on each other is a key ability in understanding the structure of language and music. Perception of such interdependencies has previously been documented in chimpanzees in the visual domain and in human infants and common squirrel monkeys with auditory playback experiments, but it remains unclear whether it typifies primates in general. Here, we investigated the ability of common marmosets (Callithrix jacchus) to recognize and respond to such dependencies. We tested subjects in a familiarization-discrimination playback experiment using stimuli composed of pure tones that either conformed or did not conform to a grammatical rule. After familiarization to sequences with dependencies, marmosets spontaneously discriminated between sequences containing and lacking dependencies (‘consistent’ and ‘inconsistent’, respectively), independent of stimulus length. Marmosets looked more often to the sound source when hearing sequences consistent with the familiarization stimuli, as previously found in human infants. Crucially, looks were coded automatically by computer software, avoiding human bias. Our results support the hypothesis that the ability to perceive dependencies at variable distances was already present in the common ancestor of all anthropoid primates (Simiiformes).
  • Versace, E., Rogge, J. R., Shelton-May, N., & Ravignani, A. (2019). Positional encoding in cotton-top tamarins (Saguinus oedipus). Animal Cognition, 22, 825-838. doi:10.1007/s10071-019-01277-y.

    Abstract

    Strategies used in artificial grammar learning can shed light into the abilities of different species to extract regularities from the environment. In the A(X)nB rule, A and B items are linked, but assigned to different positional categories and separated by distractor items. Open questions are how widespread is the ability to extract positional regularities from A(X)nB patterns, which strategies are used to encode positional regularities and whether individuals exhibit preferences for absolute or relative position encoding. We used visual arrays to investigate whether cotton-top tamarins (Saguinusoedipus) can learn this rule and which strategies they use. After training on a subset of exemplars, two of the tested monkeys successfully generalized to novel combinations. These tamarins discriminated between categories of tokens with different properties (A, B, X) and detected a positional relationship between non-adjacent items even in the presence of novel distractors. The pattern of errors revealed that successful subjects used visual similarity with training stimuli to solve the task and that successful tamarins extracted the relative position of As and Bs rather than their absolute position, similarly to what has been observed in other species. Relative position encoding appears to be favoured in different tasks and taxa. Generalization, though, was incomplete, since we observed a failure with items that during training had always been presented in reinforced arrays, showing the limitations in grasping the underlying positional rule. These results suggest the use of local strategies in the extraction of positional rules in cotton-top tamarins.

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    Supplementary file
  • Delgado, T., Ravignani, A., Verhoef, T., Thompson, B., Grossi, T., & Kirby, S. (2018). Cultural transmission of melodic and rhythmic universals: Four experiments and a model. In C. Cuskley, M. Flaherty, H. Little, L. McCrohon, A. Ravignani, & T. Verhoef (Eds.), Proceedings of the 12th International Conference on the Evolution of Language (EVOLANG XII) (pp. 89-91). Toruń, Poland: NCU Press. doi:10.12775/3991-1.019.
  • Kotz, S. A., Ravignani, A., & Fitch, W. T. (2018). The evolution of rhythm processing. Trends in Cognitive Sciences, 22(10), 896-910. doi:10.1016/j.tics.2018.08.002.
  • Lumaca, M., Ravignani, A., & Baggio, G. (2018). Music evolution in the laboratory: Cultural transmission meets neurophysiology. Frontiers in Neuroscience, 12: 246. doi:10.3389%2Ffnins.2018.00246.

    Abstract

    In recent years, there has been renewed interest in the biological and cultural evolution of music, and specifically in the role played by perceptual and cognitive factors in shaping core features of musical systems, such as melody, harmony, and rhythm. One proposal originates in the language sciences. It holds that aspects of musical systems evolve by adapting gradually, in the course of successive generations, to the structural and functional characteristics of the sensory and memory systems of learners and “users” of music. This hypothesis has found initial support in laboratory experiments on music transmission. In this article, we first review some of the most important theoretical and empirical contributions to the field of music evolution. Next, we identify a major current limitation of these studies, i.e., the lack of direct neural support for the hypothesis of cognitive adaptation. Finally, we discuss a recent experiment in which this issue was addressed by using event-related potentials (ERPs). We suggest that the introduction of neurophysiology in cultural transmission research may provide novel insights on the micro-evolutionary origins of forms of variation observed in cultural systems.
  • Ravignani, A. (2018). Darwin, sexual selection, and the origins of music. Trends in Ecology and Evolution, 33(10), 716-719. doi:10.1016/j.tree.2018.07.006.

    Abstract

    Humans devote ample time to produce and perceive music. How and why this behavioral propensity originated in our species is unknown. For centuries, speculation dominated the study of the evolutionary origins of musicality. Following Darwin’s early intuitions, recent empirical research is opening a new chapter to tackle this mystery.
  • Ravignani, A. (2018). Comment on “Temporal and spatial variation in harbor seal (Phoca vitulina L.) roar calls from southern Scandinavia” [J. Acoust. Soc. Am. 141, 1824-1834 (2017)]. The Journal of the Acoustical Society of America, 143, 504-508. doi:10.1121/1.5021770.

    Abstract

    In their recent article, Sabinsky and colleagues investigated heterogeneity in harbor seals' vocalizations. The authors found seasonal and geographical variation in acoustic parameters, warning readers that recording conditions might account for some of their results. This paper expands on the temporal aspect of the encountered heterogeneity in harbor seals' vocalizations. Temporal information is the least susceptible to variable recording conditions. Hence geographical and seasonal variability in roar timing constitutes the most robust finding in the target article. In pinnipeds, evidence of timing and rhythm in the millisecond range—as opposed to circadian and seasonal rhythms—has theoretical and interdisciplinary relevance. In fact, the study of rhythm and timing in harbor seals is particularly decisive to support or confute a cross-species hypothesis, causally linking the evolution of vocal production learning and rhythm. The results by Sabinsky and colleagues can shed light on current scientific questions beyond pinniped bioacoustics, and help formulate empirically testable predictions.
  • Ravignani, A., Chiandetti, C., & Gamba, M. (2018). L'evoluzione del ritmo. Le Scienze, (04 maggio 2018).
  • Ravignani, A., Thompson, B., Grossi, T., Delgado, T., & Kirby, S. (2018). Evolving building blocks of rhythm: How human cognition creates music via cultural transmission. Annals of the New York Academy of Sciences, 1423(1), 176-187. doi:10.1111/nyas.13610.

    Abstract

    Why does musical rhythm have the structure it does? Musical rhythm, in all its cross-cultural diversity, exhibits
    commonalities across world cultures. Traditionally, music research has been split into two fields. Some scientists
    focused onmusicality, namely the human biocognitive predispositions formusic, with an emphasis on cross-cultural
    similarities. Other scholars investigatedmusic, seen as a cultural product, focusing on the variation in worldmusical
    cultures.Recent experiments founddeep connections betweenmusicandmusicality, reconciling theseopposing views.
    Here, we address the question of how individual cognitive biases affect the process of cultural evolution of music.
    Data from two experiments are analyzed using two complementary techniques. In the experiments, participants
    hear drumming patterns and imitate them. These patterns are then given to the same or another participant to
    imitate. The structure of these initially random patterns is tracked along experimental “generations.” Frequentist
    statistics show how participants’ biases are amplified by cultural transmission, making drumming patterns more
    structured. Structure is achieved faster in transmission within rather than between participants. A Bayesian model
    approximates the motif structures participants learned and created. Our data and models suggest that individual
    biases for musicality may shape the cultural transmission of musical rhythm.

    Additional information

    nyas13610-sup-0001-suppmat.pdf
  • Ravignani, A., Thompson, B., & Filippi, P. (2018). The evolution of musicality: What can be learned from language evolution research? Frontiers in Neuroscience, 12: 20. doi:10.3389/fnins.2018.00020.

    Abstract

    Language and music share many commonalities, both as natural phenomena and as subjects of intellectual inquiry. Rather than exhaustively reviewing these connections, we focus on potential cross-pollination of methodological inquiries and attitudes. We highlight areas in which scholarship on the evolution of language may inform the evolution of music. We focus on the value of coupled empirical and formal methodologies, and on the futility of mysterianism, the declining view that the nature, origins and evolution of language cannot be addressed empirically. We identify key areas in which the evolution of language as a discipline has flourished historically, and suggest ways in which these advances can be integrated into the study of the evolution of music.
  • Ravignani, A. (2018). Spontaneous rhythms in a harbor seal pup calls. BMC Research Notes, 11: 3. doi:10.1186/s13104-017-3107-6.

    Abstract

    Objectives: Timing and rhythm (i.e. temporal structure) are crucial, though historically neglected, dimensions of animal communication. When investigating these in non-human animals, it is often difficult to balance experimental control and ecological validity. Here I present the first step of an attempt to balance the two, focusing on the timing of vocal rhythms in a harbor seal pup (Phoca vitulina). Collection of this data had a clear aim: To find spontaneous vocal rhythms in this individual in order to design individually-adapted and ecologically-relevant stimuli for a later playback experiment. Data description: The calls of one seal pup were recorded. The audio recordings were annotated using Praat, a free software to analyze vocalizations in humans and other animals. The annotated onsets and offsets of vocalizations were then imported in a Python script. The script extracted three types of timing information: the duration of calls, the intervals between calls’ onsets, and the intervals between calls’ maximum-intensity peaks. Based on the annotated data, available to download, I provide simple descriptive statistics for these temporal measures, and compare their distributions.
  • Ravignani, A., Garcia, M., Gross, S., de Reus, K., Hoeksema, N., Rubio-Garcia, A., & de Boer, B. (2018). Pinnipeds have something to say about speech and rhythm. In C. Cuskley, M. Flaherty, H. Little, L. McCrohon, A. Ravignani, & T. Verhoef (Eds.), Proceedings of the 12th International Conference on the Evolution of Language (EVOLANG XII) (pp. 399-401). Toruń, Poland: NCU Press. doi:10.12775/3991-1.095.
  • Ravignani, A., & Verhoef, T. (2018). Which melodic universals emerge from repeated signaling games?: A Note on Lumaca and Baggio (2017). Artificial Life, 24(2), 149-153. doi:10.1162/ARTL_a_00259.

    Abstract

    Music is a peculiar human behavior, yet we still know little as to why and how music emerged. For centuries, the study of music has been the sole prerogative of the humanities. Lately, however, music is being increasingly investigated by psychologists, neuroscientists, biologists, and computer scientists. One approach to studying the origins of music is to empirically test hypotheses about the mechanisms behind this structured behavior. Recent lab experiments show how musical rhythm and melody can emerge via the process of cultural transmission. In particular, Lumaca and Baggio (2017) tested the emergence of a sound system at the boundary between music and language. In this study, participants were given random pairs of signal-meanings; when participants negotiated their meaning and played a “ game of telephone ” with them, these pairs became more structured and systematic. Over time, the small biases introduced in each artificial transmission step accumulated, displaying quantitative trends, including the emergence, over the course of artificial human generations, of features resembling properties of language and music. In this Note, we highlight the importance of Lumaca and Baggio ʼ s experiment, place it in the broader literature on the evolution of language and music, and suggest refinements for future experiments. We conclude that, while psychological evidence for the emergence of proto-musical features is accumulating, complementary work is needed: Mathematical modeling and computer simulations should be used to test the internal consistency of experimentally generated hypotheses and to make new predictions.
  • Ravignani, A., Thompson, B., Lumaca, M., & Grube, M. (2018). Why do durations in musical rhythms conform to small integer ratios? Frontiers in Computational Neuroscience, 12: 86. doi:10.3389/fncom.2018.00086.

    Abstract

    One curious aspect of human timing is the organization of rhythmic patterns in small integer ratios. Behavioral and neural research has shown that adjacent time intervals in rhythms tend to be perceived and reproduced as approximate fractions of small numbers (e.g., 3/2). Recent work on iterated learning and reproduction further supports this: given a randomly timed drum pattern to reproduce, participants subconsciously transform it toward small integer ratios. The mechanisms accounting for this “attractor” phenomenon are little understood, but might be explained by combining two theoretical frameworks from psychophysics. The scalar expectancy theory describes time interval perception and reproduction in terms of Weber's law: just detectable durational differences equal a constant fraction of the reference duration. The notion of categorical perception emphasizes the tendency to perceive time intervals in categories, i.e., “short” vs. “long.” In this piece, we put forward the hypothesis that the integer-ratio bias in rhythm perception and production might arise from the interaction of the scalar property of timing with the categorical perception of time intervals, and that neurally it can plausibly be related to oscillatory activity. We support our integrative approach with mathematical derivations to formalize assumptions and provide testable predictions. We present equations to calculate durational ratios by: (i) parameterizing the relationship between durational categories, (ii) assuming a scalar timing constant, and (iii) specifying one (of K) category of ratios. Our derivations provide the basis for future computational, behavioral, and neurophysiological work to test our model.
  • Ravignani, A., & Thompson, B. (2017). A note on ‘Noam Chomsky – What kind of creatures are we? Language in Society, 46(3), 446-447. doi:10.1017/S0047404517000288.
  • Ravignani, A., Honing, H., & Kotz, S. A. (2017). Editorial: The evolution of rhythm cognition: Timing in music and speech. Frontiers in Human Neuroscience, 11: 303. doi:10.3389/fnhum.2017.00303.

    Abstract

    This editorial serves a number of purposes. First, it aims at summarizing and discussing 33 accepted contributions to the special issue “The evolution of rhythm cognition: Timing in music and speech.” The major focus of the issue is the cognitive neuroscience of rhythm, intended as a neurobehavioral trait undergoing an evolutionary process. Second, this editorial provides the interested reader with a guide to navigate the interdisciplinary contributions to this special issue. For this purpose, we have compiled Table 1, where methods, topics, and study species are summarized and related across contributions. Third, we also briefly highlight research relevant to the evolution of rhythm that has appeared in other journals while this special issue was compiled. Altogether, this editorial constitutes a summary of rhythm research in music and speech spanning two years, from mid-2015 until mid-2017
  • Ravignani, A., & Sonnweber, R. (2017). Chimpanzees process structural isomorphisms across sensory modalities. Cognition, 161, 74-79. doi:10.1016/j.cognition.2017.01.005.
  • Ravignani, A., Gross, S., Garcia, M., Rubio-Garcia, A., & De Boer, B. (2017). How small could a pup sound? The physical bases of signaling body size in harbor seals. Current Zoology, 63(4), 457-465. doi:10.1093/cz/zox026.

    Abstract

    Vocal communication is a crucial aspect of animal behavior. The mechanism which most mammals use to vocalize relies on three anatomical components. First, air overpressure is generated inside the lower vocal tract. Second, as the airstream goes through the glottis, sound is produced via vocal fold vibration. Third, this sound is further filtered by the geometry and length of the upper vocal tract. Evidence from mammalian anatomy and bioacoustics suggests that some of these three components may covary with an animal’s body size. The framework provided by acoustic allometry suggests that, because vocal tract length (VTL) is more strongly constrained by the growth of the body than vocal fold length (VFL), VTL generates more reliable acoustic cues to an animal’s size. This hypothesis is often tested acoustically but rarely anatomically, especially in pinnipeds. Here, we test the anatomical bases of the acoustic allometry hypothesis in harbor seal pups Phoca vitulina. We dissected and measured vocal tract, vocal folds, and other anatomical features of 15 harbor seals post-mortem. We found that, while VTL correlates with body size, VFL does not. This suggests that, while body growth puts anatomical constraints on how vocalizations are filtered by harbor seals’ vocal tract, no such constraints appear to exist on vocal folds, at least during puppyhood. It is particularly interesting to find anatomical constraints on harbor seals’ vocal tracts, the same anatomical region partially enabling pups to produce individually distinctive vocalizations.
  • Ravignani, A., & Norton, P. (2017). Measuring rhythmic complexity: A primer to quantify and compare temporal structure in speech, movement, and animal vocalizations. Journal of Language Evolution, 2(1), 4-19. doi:10.1093/jole/lzx002.

    Abstract

    Research on the evolution of human speech and phonology benefits from the comparative approach: structural, spectral, and temporal features can be extracted and compared across species in an attempt to reconstruct the evolutionary history of human speech. Here we focus on analytical tools to measure and compare temporal structure in human speech and animal vocalizations. We introduce the reader to a range of statistical methods usable, on the one hand, to quantify rhythmic complexity in single vocalizations, and on the other hand, to compare rhythmic structure between multiple vocalizations. These methods include: time series analysis, distributional measures, variability metrics, Fourier transform, auto- and cross-correlation, phase portraits, and circular statistics. Using computer-generated data, we apply a range of techniques, walking the reader through the necessary software and its functions. We describe which techniques are most appropriate to test particular hypotheses on rhythmic structure, and provide possible interpretations of the tests. These techniques can be equally well applied to find rhythmic structure in gesture, movement, and any other behavior developing over time, when the research focus lies on its temporal structure. This introduction to quantitative techniques for rhythm and timing analysis will hopefully spur additional comparative research, and will produce comparable results across all disciplines working on the evolution of speech, ultimately advancing the field.

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  • Ravignani, A. (2017). Interdisciplinary debate: Agree on definitions of synchrony [Correspondence]. Nature, 545, 158. doi:10.1038/545158c.
  • Ravignani, A., & Madison, G. (2017). The paradox of isochrony in the evolution of human rhythm. Frontiers in Psychology, 8: 1820. doi:10.3389/fpsyg.2017.01820.

    Abstract

    Isochrony is crucial to the rhythm of human music. Some neural, behavioral and anatomical traits underlying rhythm perception and production are shared with a broad range of species. These may either have a common evolutionary origin, or have evolved into similar traits under different evolutionary pressures. Other traits underlying rhythm are rare across species, only found in humans and few other animals. Isochrony, or stable periodicity, is common to most human music, but isochronous behaviors are also found in many species. It appears paradoxical that humans are particularly good at producing and perceiving isochronous patterns, although this ability does not conceivably confer any evolutionary advantage to modern humans. This article will attempt to solve this conundrum. To this end, we define the concept of isochrony from the present functional perspective of physiology, cognitive neuroscience, signal processing, and interactive behavior, and review available evidence on isochrony in the signals of humans and other animals. We then attempt to resolve the paradox of isochrony by expanding an evolutionary hypothesis about the function that isochronous behavior may have had in early hominids. Finally, we propose avenues for empirical research to examine this hypothesis and to understand the evolutionary origin of isochrony in general.
  • Ravignani, A. (2017). Visualizing and interpreting rhythmic patterns using phase space plots. Music Perception, 34(5), 557-568. doi:10.1525/MP.2017.34.5.557.

    Abstract

    STRUCTURE IN MUSICAL RHYTHM CAN BE MEASURED using a number of analytical techniques. While some techniques—like circular statistics or grammar induction—rely on strong top-down assumptions, assumption-free techniques can only provide limited insights on higher-order rhythmic structure. I suggest that research in music perception and performance can benefit from systematically adopting phase space plots, a visualization technique originally developed in mathematical physics that overcomes the aforementioned limitations. By jointly plotting adjacent interonset intervals (IOI), the motivic rhythmic structure of musical phrases, if present, is visualized geometrically without making any a priori assumptions concerning isochrony, beat induction, or metrical hierarchies. I provide visual examples and describe how particular features of rhythmic patterns correspond to geometrical shapes in phase space plots. I argue that research on music perception and systematic musicology stands to benefit from this descriptive tool, particularly in comparative analyses of rhythm production. Phase space plots can be employed as an initial assumption-free diagnostic to find higher order structures (i.e., beyond distributional regularities) before proceeding to more specific, theory-driven analyses.
  • Filippi, P., Jadoul, Y., Ravignani, A., Thompson, B., & de Boer, B. (2016). Seeking Temporal Predictability in Speech: Comparing Statistical Approaches on 18 World Languages. Frontiers in Human Neuroscience, 10: 586. doi:10.3389/fnhum.2016.00586.

    Abstract

    Temporal regularities in speech, such as interdependencies in the timing of speech events, are thought to scaffold early acquisition of the building blocks in speech. By providing on-line clues to the location and duration of upcoming syllables, temporal structure may aid segmentation and clustering of continuous speech into separable units. This hypothesis tacitly assumes that learners exploit predictability in the temporal structure of speech. Existing measures of speech timing tend to focus on first-order regularities among adjacent units, and are overly sensitive to idiosyncrasies in the data they describe. Here, we compare several statistical methods on a sample of 18 languages, testing whether syllable occurrence is predictable over time. Rather than looking for differences between languages, we aim to find across languages (using clearly defined acoustic, rather than orthographic, measures), temporal predictability in the speech signal which could be exploited by a language learner. First, we analyse distributional regularities using two novel techniques: a Bayesian ideal learner analysis, and a simple distributional measure. Second, we model higher-order temporal structure—regularities arising in an ordered series of syllable timings—testing the hypothesis that non-adjacent temporal structures may explain the gap between subjectively-perceived temporal regularities, and the absence of universally-accepted lower-order objective measures. Together, our analyses provide limited evidence for predictability at different time scales, though higher-order predictability is difficult to reliably infer. We conclude that temporal predictability in speech may well arise from a combination of individually weak perceptual cues at multiple structural levels, but is challenging to pinpoint.
  • Geambaşu, A., Ravignani, A., & Levelt, C. C. (2016). Preliminary experiments on human sensitivity to rhythmic structure in a grammar with recursive self-similarity. Frontiers in Neuroscience, 10: 281. doi:10.3389/fnins.2016.00281.

    Abstract

    We present the first rhythm detection experiment using a Lindenmayer grammar, a self-similar recursive grammar shown previously to be learnable by adults using speech stimuli. Results show that learners were unable to correctly accept or reject grammatical and ungrammatical strings at the group level, although five (of 40) participants were able to do so with detailed instructions before the exposure phase.
  • Ravignani, A., Delgado, T., & Kirby, S. (2016). Musical evolution in the lab exhibits rhythmic universals. Nature Human Behaviour, 1: 0007. doi:10.1038/s41562-016-0007.

    Abstract

    Music exhibits some cross-cultural similarities, despite its variety across the world. Evidence from a broad range of human cultures suggests the existence of musical universals1, here defined as strong regularities emerging across cultures above chance. In particular, humans demonstrate a general proclivity for rhythm2, although little is known about why music is particularly rhythmic and why the same structural regularities are present in rhythms around the world. We empirically investigate the mechanisms underlying musical universals for rhythm, showing how music can evolve culturally from randomness. Human participants were asked to imitate sets of randomly generated drumming sequences and their imitation attempts became the training set for the next participants in independent transmission chains. By perceiving and imitating drumming sequences from each other, participants turned initially random sequences into rhythmically structured patterns. Drumming patterns developed into rhythms that are more structured, easier to learn, distinctive for each experimental cultural tradition and characterized by all six statistical universals found among world music1; the patterns appear to be adapted to human learning, memory and cognition. We conclude that musical rhythm partially arises from the influence of human cognitive and biological biases on the process of cultural evolution.

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