How and why did language evolve in humans? And what can we learn from communication in other animal species? Although human language is often seen as unique, many animals have surprisingly complex communication systems. Some of these even exhibit characteristics that are also found in language. In the 1980s, researchers discovered that harbour seals can imitate human speech. This made the species a promising model for research into the evolution of language. Until now, however, there has been no coherent picture of which communicative characteristics seals and humans actually share. This thesis offers an interdisciplinary overview of vocal communication in harbour seals. It examines, among other things, vocal flexibility, sound development, social adaptation and turn-taking during interactions. All studies used non-invasive methods, such as sound recordings, playback experiments and anatomical measurements. In addition, the thesis contains an overview of rhythmic patterns in social communication in a variety of animal species, from mammals and birds to frogs and insects. The results show that seals share important communicative characteristics with other animals and with human language. This thesis thus underlines the value of the common seal as a comparative model and shows how a comparative approach can help to understand the biological and social origins of communication.
Koen de Reus was born in Emmen in 1995. He studied Liberal Arts and Sciences at University College Roosevelt in Middelburg, where he specialised in biology, psychology and cognitive sciences, with a minor in statistics. He then completed a Master's degree in Wild Animal Biology at the Royal Veterinary College in London. He wrote his Master's thesis at the Pieterburen Seal Centre, focusing on the vocal development of harbour seal pups. In the years that followed, he combined research on seals with teaching as a tutor at Erasmus University College. In 2020, he began a joint PhD at the Vrije Universiteit Brussel and the Donders Centre for Cognition, with the Max Planck Institute for Psycholinguistics as his host institute. He is currently a lecturer in Life Sciences at Erasmus University College.