References
Fitch, W. T. The evolution of language: a comparative review. Biol. Philos. 20, 193–230 (2005).
Macedonia, J. M. & Evans, C. S. Variation among mammalian alarm call systems and the problem of meaning in animal signals. Ethology 93, 177–197 (1993).
Clay, Z., Smith, C. L. & Blumstein, D. T. Food-associated vocalizations in mammals and birds: what do these calls really mean? Anim. Behav. 83, 323–330 (2012).
Wheeler, B. C. & Fischer, J. Functionally referential signals: a promising paradigm whose time has passed. Evol. Anthropol. 21, 195–205 (2012).
Smith, E. A. Communication and collective action: language and the evolution of human cooperation. Evol. Hum. Behav. 31, 231–245 (2010).
Dingemanse, M., Blasi, D. E., Lupyan, G., Christiansen, M. H. & Monaghan, P. Arbitrariness, iconicity, and systematicity in language. Trends Cogn. Sci. 19, 603–615 (2015).
King, S. L. & Janik, V. M. Bottlenose dolphins can use learned vocal labels to address each other. Proc. Natl Acad. Sci. USA 110, 13216–13221 (2013).
Balsby, T. J. S., Momberg, J. V. & Dabelsteen, T. Vocal imitation in parrots allows addressing of specific individuals in a dynamic communication network. PLoS ONE 7, e49747 (2012).
Janik, V. M. & Sayigh, L. S. Communication in bottlenose dolphins: 50 years of signature whistle research. J. Comp. Physiol. A 199, 479–489 (2013).
Poole, J. H., Tyack, P. L., Stoeger-Horwath, A. S. & Watwood, S. Elephants are capable of vocal learning. Nature 434, 455–456 (2005).
Stoeger, A. S. et al. An Asian elephant imitates human speech. Curr. Biol. 22, 2144–2148 (2012).
Soltis, J., Leong, K. & Savage, A. African elephant vocal communication II: rumble variation reflects the individual identity and emotional state of callers. Anim. Behav. 70, 589–599 (2005).
Clemins, P. J., Johnson, M. T., Leong, K. M. & Savage, A. Automatic classification and speaker identification of African elephant (Loxodonta africana) vocalizations. J. Acoust. Soc. Am. 117, 956–963 (2005).
McComb, K., Moss, C., Sayialel, S. & Baker, L. Unusually extensive networks of vocal recognition in African elephants. Anim. Behav. 59, 1103–1109 (2000).
Poole, J. H. in The Amboseli Elephants: A Long-Term Perspective on a Long-Lived Mammal (eds Moss, C. J. et al.) 125–159 (Univ. Chicago Press, 2011).
Breiman, L. Random forests. Mach. Learn. 45, 5–32 (2001).
Rhodes, J. S., Cutler, A. & Moon, K. R. Geometry- and accuracy-preserving random forest proximities. IEEE Trans. Pattern Anal. Mach. Intell. 45, 10947–10959 (2023).
Foley, N. M. et al. A genomic timescale for placental mammal evolution. Science 380, eabl8189 (2023).
Dahlin, C. R., Young, A. M., Cordier, B., Mundry, R. & Wright, T. F. A test of multiple hypotheses for the function of call sharing in female budgerigars, Melopsittacus undulatus. Behav. Ecol. Sociobiol. 68, 145–161 (2014).
Wanker, R., Sugama, Y. & Prinage, S. Vocal labelling of family members in spectacled parrotlets, Forpus conspicillatus. Anim. Behav. 70, 111–118 (2005).
Prat, Y., Taub, M. & Yovel, Y. Everyday bat vocalizations contain information about emitter, addressee, context, and behavior. Sci. Rep. 6, 39419 (2016).
Wittemyer, G., Douglas-Hamilton, I. & Getz, W. M. The socioecology of elephants: analysis of the processes creating multitiered social structures. Anim. Behav. 69, 1357–1371 (2005).
Archie, E. A., Moss, C. J. & Alberts, S. C. The ties that bind: genetic relatedness predicts the fission and fusion of social groups in wild African elephants. Proc. R. Soc. B 273, 513–522 (2006).
Howard, D. J., Gengler, C. & Jain, A. What’s in a name? A complimentary means of persuasion. J. Consum. Res. 22, 200–211 (1995).
King, S. L., Sayigh, L. S., Wells, R. S., Fellner, W. & Janik, V. M. Vocal copying of individually distinctive signature whistles in bottlenose dolphins. Proc. R. Soc. B 280, 20130053 (2013).
Baotic, A. & Stoeger, A. S. Sexual dimorphism in African elephant social rumbles. PLoS ONE 12, e0177411 (2017).
Stoeger, A. S., Zeppelzauer, M. & Baotic, A. Age-group estimation in free-ranging African elephants based on acoustic cues of low-frequency rumbles. Bioacoustics 23, 231–246 (2014).
Zaman, S. R., Sadekeen, D., Alfaz, M. A. & Shahriyar, R. One source to detect them all: gender, age, and emotion detection from voice. In Proc. IEEE 45th Annual Computers, Software, and Applications Conference 338–343 (IEEE, 2021).
Berg, K. S., Delgado, S., Cortopassi, K. A., Beissinger, S. R. & Bradbury, J. W. Vertical transmission of learned signatures in a wild parrot. Proc. R. Soc. B 279, 585–591 (2012).
Stevens, S. S., Volkmann, J. & Newman, E. B. A scale for the measurement of the psychological magnitude pitch. J. Acoust. Soc. Am. 8, 185–190 (1937).
Vernes, S. C. et al. The multi-dimensional nature of vocal learning. Philos. Trans. R. Soc. B 376, 20200236 (2021).
Bradbury, J. W. & Balsby, T. J. S. The functions of vocal learning in parrots. Behav. Ecol. Sociobiol. 70, 293–312 (2016).
Connor, R. C. Dolphin social intelligence: complex alliance relationships in bottlenose dolphins and a consideration of selective environments for extreme brain size evolution in mammals. Philos. Trans. R. Soc. Lond. B 362, 587–602 (2007).
Bachorec, E. et al. Spatial networks differ when food supply changes: foraging strategy of Egyptian fruit bats. PLoS ONE 15, e0229110 (2020).
Kerth, G., Perony, N. & Schweitzer, F. Bats are able to maintain long-term social relationships despite the high fission–fusion dynamics of their groups. Proc. R. Soc. B 278, 2761–2767 (2011).
Moss, C. J. & Poole, J. H. in Primate Social Relationships: An Integrated Approach (ed. Hinde, R. A.) 315–325 (Blackwell Science, 1983).
Altmann, J. Observational study of behavior: sampling methods. Behaviour 49, 227–267 (1974).
de Silva, S. Acoustic communication in the Asian elephant, Elephas maximus maximus. Behaviour 147, 825–852 (2010).
R Core Team. R: a language and environment for statistical computing. R Foundation for Statistical Computing https://www.R-project.org (2022).
Sueur, J., Aubin, T. & Simonis, C. seewave, a free modular tool for sound analysis. Bioacoustics 18, 213–226 (2008).
Ligges, U., Krey, S., Mersmann, O. & Schnackenberg, S. tuneR: analysis of music and speech. R Project https://CRAN.R-projet.org/package=tuneR (2018).
Anikin, A. Soundgen: an open-source tool for synthesizing nonverbal vocalizations. Behav. Res. Methods 51, 778–792 (2019).
Heffner, R. S. & Heffner, H. E. Hearing in the elephant (Elephas maximus): absolute sensitivity, frequency discrimination, and sound localization. J. Comp. Physiol. Psychol. 96, 926–944 (1982).
Ren, Y. et al. A framework for bioacoustic vocalization analysis using hidden Markov models. Algorithms 2, 1410–1428 (2009).
Davis, S. B. & Mermelstein, P. Comparison of parametric representations for monosyllabic word recognition. IEEE Trans. Acoust. 28, 357–366 (1980).
Sykulsi, M. rpca: RobustPCA: decompose a matrix into low-rank and sparse components. R package version 0.2.3. R Project https://CRAN.R-project.org/package=rpca (2015).
Thomson, D. J. Spectrum estimation and harmonic analysis. Proc. IEEE 70, 1055–1096 (1982).
Correll, J., Mellinger, C. & Pedersen, E. J. Flexible approaches for estimating partial eta squared in mixed-effects models with crossed random factors. Behav. Res. Methods 54, 1626–1642 (2022).
Wright, M. N. & Ziegler, A. ranger: a fast implementation of random forests for high dimensional data in C++ and R. J. Stat. Softw. 77, 1–17 (2017).
Wittemyer, G. & Getz, W. M. Hierarchical dominance structure and social organization in African elephants, Loxodonta africana. Anim. Behav. 73, 671–681 (2007).
Archie, E. A., Morrison, T. A., Foley, C. A. H., Moss, C. J. & Alberts, S. C. Dominance rank relationships among wild female African elephants, Loxodonta africana. Anim. Behav. 71, 117–127 (2006).
Archie, E. A., Moss, C. J. & Alberts, S. C. in The Amboseli Elephants: A Long-Term Perspective on a Long-Lived Mammal (eds Moss, C. J. et al.) 238–245 (Univ. Chicago Press, 2011).
Blanca, M. J., Alarcón, R., Arnau, J., Bono, R. & Bendayan, R. Non-normal data: is ANOVA still a valid option? Psicothema 29, 552–557 (2017).
Strobl, C., Boulesteix, A. L., Kneib, T., Augustin, T. & Zeileis, A. Conditional variable importance for random forests. BMC Bioinform. 9, 307 (2008).
Poole, J. H., Payne, K., Langbauer, W. R. J. & Moss, C. J. The social contexts of some very low-frequency calls of African elephants. Behav. Ecol. Sociobiol. 22, 385–392 (1988).
Poole, J. H. & Granli, P. in The Amboseli Elephants: A Long-Term Perspective on a Long-Lived Mammal (eds Moss, C. J. et al.) 109–124 (Univ. Chicago Press, 2011).
Therneau, T. M. coxme: mixed effects cox models. R package version 2.2-18.1. R Project https://CRAN.R-project.org/package=coxme (2019).
Bates, D., Mächler, M., Bolker, B. M. & Walker, S. C. Fitting linear mixed-effects models using lme4. J. Stat. Softw. 67, 1–48 (2015).
Kleiber, C. & Zeileis, A. Applied Econometrics with R (Springer, 2008).
Pardo, M. African elephants address one another with individually specific calls. Dryad https://doi.org/10.5061/dryad.hmgqnk9nj (2024).
Pardo, M. African elephants address one another with individually specific calls. Zenodo https://doi.org/10.5281/zenodo.10576772 (2024).
