Relationships between vocal ontogeny and vocal tract anatomy in harbour seals (Phoca vitulina)

Understanding the origins and evolution of human speech benefits from a multidisciplinary and comparative approach. Research on animal models has already provided some valuable insight into the biological underpinnings of vocal communication. One important focus in the field of animal communication is sound production. The current literature on this topic hosts a great number of studies on avian species and our closer relatives, non-human primates. However, many pinniped species have been reported to have wide vocal repertoires, often producing call types in specific behavioral contexts (Ralls et al., 1985; Mathevon et al., 2017; Charrier et al., 2009). In fact, the vocal abilities of pinnipeds are better than was historically believed (Ravignani et al., 2016). Moreover, pinnipeds are phylogenetically closer to humans than the well-studied birds (O’Leary et al, 2013) and share some anatomical similarities to the human vocal apparatus (Fitch, 2000). Here, we: (i) report on longitudinal data on vocal ontogeny in harbor seal pups, (ii) complement the bioacoustic findings with results from a large anatomical data set of larynges, and (iii) critically compare our findings with available literature on harbor seal sound production. Taken together, they suggest that phocids are good candidates for animal models in future research on the evolution of human speech