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19th Ave New York, NY 95822, USA

OUR RESEARCH

We carry out research in a wide range of fields related to primate evolution and ecology. A key feature of PEER Group research is the use of sound to answer a range of fundamental and applied questions in ecology and evolution. We do not study infinite monkey theorem, but we do have a cracking blog called ‘the monkey’s typewriter’.

MULTI-DISCIPLINARY INTERNATIONAL RESEARCH INTO PRIMATE EVOLUTION AND ECOLOGY

PEER Group team members carry out research in a wide range of fields related to primate evolution and ecology. A key feature that connects much of our research is the use of sound. Our work can broadly be divided into four main areas: bioacoustics (i.e., how animals produce, detect, and respond to sound), primate communication and the evolution of language, eco-acoustics for animal welfare and conservation, and macro-evolution and phylogenetic comparative methods.

Bioacoustics

Bioacoustics is the study of how animals produce, detect, and respond to sound. We use bioacoustics methods to ask a range of ecological and evolutionary questions, as well as more applied research in the context of welfare and conservation. We take a broad comparative perspective, ranging from detailed descriptions of vocal anatomy, through to recording animal sounds, carrying out playback experiments, and using phylogenetic analyses to test evolutionary hypotheses. For example, we published the first known example of an evolutionary trade-off between investment in vocal traits and sperm competition (Dunn et al., 2015) – what we call ‘balls vs. calls’ (see media coverage). More recently, we reported the first evidence for asymmetric call convergence among primates, whereby one species adopts the ‘accent’ of another in areas of sympatry (Sobroza et al. 2021).

Ongoing research in bioacoustics in PEER Group includes: 1) field research into the evolution and ecology of howler monkey vocalisations in Mexico (with Pedro Dias); 2) field and captive research into the role of non-linear phenomena (or ‘chaos’) in primate communication (with Jen Muir); 3) observational and experimental research into the structure, complexity, and use of vocal repertoires in corvids (with Sam Reynolds and Claudia Wascher); and d) field research into vocal interactions among tamarin species in the Brazilian Amazon (with Tainara Sobroza).

The evolution of language

Our research forms a core part of a large and long-running international collaboration with Prof. Tecumseh Fitch (Vienna) and Prof. Takeshi Nishimura (Kyoto) seeking to understand the evolution of human speech through comparative studies of vocal anatomy. We use a combination of in vivo observations of phonation, high speed video observations of excised larynges, anatomical investigations using high resolution CT and MRI scanning, and computer simulation modelling of vocal fold dynamics.

Our recent results have shown that the primate larynx is larger, more decoupled from body size, and under faster rates of evolution than that of other mammals (Bowling et al. 2020). We have also found, paradoxically, that the increased complexity of human spoken language entailed evolutionary simplification of our vocal anatomy (Nishimura et al. in press). Ongoing research in this area uses computed tomography, geometric morphometrics, and machine learning to create 3D models of the mammalian larynx and we are continuing to increase our taxonomic coverage and digital datasets. Jacob Dunn is the Director of the Harrison Collection at ARU, where we house a collection of over 400 larynx specimens, which are available for research.

Eco-acoustics for animal welfare and conservation

In recent years, technological advances have revolutionised our ability to study sound, with advances in equipment, data storage and analytical methods. We have recently started using passive acoustic monitoring and machine learning, alongside more traditional bioacoustics methods to investigate the effects of human noise on primate behaviour, physiology, and cognition. In collaboration with the Durrell Wildlife Conservation Trust, we currently run a new research project on captive and wild pied tamarins – one of the world’s most endangered primates (Fay Clark, Fiene Steinbrecher).

We are studying the impacts of anthropogenic noise on wild populations of primates (Tainara Sobroza) in the Amazon and carry out controlled playback experiments on a captive population at Jersey Zoo (Fiene Steinbrecher). We have also recently begun a project investigating the impacts of construction noise on captive great ape welfare in partnership with Jersey Zoo and Twycross Zoo. Here we are investigating the impacts of zoo construction (e.g., visual impacts, sound and vibration, air quality) on gorillas, chimpanzees, bonobos and orangutans (Nora Kopsch). This research is in its first year, so there are not many formal outputs yet, but we look forward to reporting back soon!

Macro-evolution and phylogenetic comparative methods

We have broad interests in the evolutionary modelling of functional traits – particularly those relevant to our understanding of human evolution. Alongside modelling laryngeal evolution, we also run projects on the mammalian brain using state of the art phylogenetic methods. We have recently shown that major transitions in the mammalian brain are often primarily characterised by changes in body size, and that the largest-brained mammals achieved large relative brain sizes by highly divergent paths (Smaers et al. 2021). We also investigate the evolution of the primate hyoid (Harris, Palkovitz, O’Mahoney), knee (Orme), sclera (Mearing), long bones (O’Mahoney, Orme), and coat colour (Sutherland).

We use a range of methods to model evolutionary processes, including phylogenetic generalized least squares (PGLS), Bayesian multipeak Ornstein-Uhlenbeck (OU) modelling, phylogenetic analysis of covariance, and more. Much of this work is carried out in collaboration with Prof. Jeroen Smaers from Stony Brook University. We use phylogenetic inference (and recent advances in molecular phylogeny) to estimate how traits have changed across millions of years of evolution. We use phytools and other packages in the R environment for comparative analyses. More information about these can be found on Liam Revell’s excellent website.

References

Key publications: BIOACOUSTICS

Sobroza T, Pequeno PACL, Gordo M, Dunn JC, Spironello WC, Rabelo RM, Barnett APA (2021). Convergent character displacement in sympatric tamarin calls (Saguinus spp.). Behavioural Ecology & Sociobiology, 75 (88).

Garcia M, Dunn JC (2019). No evidence that maximum fundamental frequency reflects selection for signal diminution in bonobos. Current Biology, 29, 732-733.

Garcia M, Herbst C, Bowling D, Dunn JC, Fitch WT (2019). Acoustic allometry revisited: morphological determinants of fundamental frequency in primate vocal production. Nature Scientific Reports 7: 10450.

Dunn JC, Halenar L, Davies T, Cristóbal-Azkarate J, Fitch WT, Knapp L (2015). Evolutionary tradeoff between vocal tract and testes dimensions in howler monkeys. Current Biology 25: 2839-2844.

Key publications: THE EVOLUTION OF LANGUAGE

Nishimura T, Tokuda IT, Miyachi S, Dunn JC, Herbst C, Ishimura K, Kaneko A, Kinoshita Y, Koda H, Saers JP, Imai H, Matsuda T, Larsen ON, Jürgens U, Hirabayashi H, Kojima S, Fitch WT. Evolutionary loss of complexity in human vocal anatomy as an adaptation for speech. Science (in press).

Bowling D, Hoeschelle M, Dunn JC (2021). Progress without exclusion in the search for an evolutionary basis of music. Behavioural and Brain Sciences 44, e97.

Bowling DL, Dunn JC, Smaers J, Garcia M, Kerney M, Stewart A, Hanke G, Kitchener A, Handschuhe S, Dengg S, Gumpenberger M & Fitch WT. Rapid evolution of the primate larynx. PLOS Biology 18(8): e3000764.

Dunn JC & Smaers JB. Neural correlates of vocal complexity in primates. Frontiers in Neuroscience 12: 534.

Dunn JC. Sexual selection and the loss of laryngeal air sacs during the evolution of speech. Anthropological Science 126: 29-34.

Key publications: ECO-ACOUSTICS FOR ANIMAL WELFARE AND CONSERVATION

Clark F, Dunn JC. From soundwave to soundscape: a guide to acoustic research in captive animal environments. Frontiers in Veterinary Science (in press).

Key publications: MACRO-EVOLUTION AND PHYLOGENETIC COMPARATIVE METHODS

Smaers JB, Rothman RS, Hudson DR, Balanoff AM, Beatty B, Dechmann DKN, de Vries D, Dunn JC, Fleagle JG, Gilbert CC, Goswami A, Iwaniuk AN, Jungers W, Kerney M, Ksepka DT, Manger PR, Mongle CS, Rohlf FJ, Smith NA, Soligo C, Weisbecker V & Safi K (2021). The evolution of mammalian brain size. Science Advances DOI:10.1126/sciadv.abe2101

Bowling DL, Dunn JC, Smaers J, Garcia M, Kerney M, Stewart A, Hanke G, Kitchener A, Handschuhe S, Dengg S, Gumpenberger M & Fitch WT. Rapid evolution of the primate larynx. PLOS Biology 18(8): e3000764

Dunn JC, Halenar L, Davies T, Cristóbal-Azkarate J, Fitch WT, Knapp L (2015). Evolutionary tradeoff between vocal tract and testes dimensions in howler monkeys. Current Biology 25: 2839-2844.