“Human beings often see their communication as more complex than that of animals,” Andrea Ravignani, the study’s author, explained. “What we seem in baby seals is rather astonishing: even at the age of four weeks, they already seem to have a very precise and flexible timing in their cries, comparable in a certain manner to the variation that can be observed in human conversations.”
To demonstrate this, the researcher has developed a “playback test”, a technique also used to understand the capacities of human babies at the pre-verbal stage. Sounds are played while varying their acoustic characteristics. The reaction of the human baby (or in this case, baby seal) is then measured.
Andrea Ravignani ran this test on a four-week-old animal that had been housed, alone, in a research and rehabilitation centre for seals at Pieterburen in the Netherlands. He prepared audio recordings with the voices of other baby seals with varying degrees of geographical proximity. The cries were then replayed with different rhythmic structures to test the young animal’s reactions, for example when its simulated peers cried more rapidly or slowly, or in a more or less predictable manner. The researcher wished to show that the baby seal learned the rhythm of its peers and adapted its cry to avoid any overlapping with them.
These results provide a new angle for the theory of animal (and human) communication since, in the past, the accent was mainly on its spectral dimension (for example, the power or range of a sound). The VUB research now shows that in seal communication, rhythm is at least as important as, if not more important than, the spectral dimension.
Moreover, the discovery now makes it possible to better understand the behaviour of babies and has interesting implications for the study of the origin and evolution of the language and musical capacities of humans.
Since submitting his article for publication, Ravignani has tested other baby seals. The results suggest that they demonstrate in an interactive way a vocal behaviour similar to that of man.
His research has been published in the Journal of Comparative Psychology.