Baby seals change their voices to be understood, study finds
Pinnipeds – animals such as seals and walruses that belong to the order Pinnipedia – are excellent models of vocal learning because they are closer than other species to humans in terms of evolutionary development and diversification, have wrote the authors.
The authors then tested eight healthy, unrelated, wild-born harbor seals aged 1 to 3 weeks from the Seal Rehabilitation and Research Center in the Netherlands. This center ultimately releases the seals into the wild.
When the seals heard a speaker play a 45-minute recording of loud, low, or no noise over several days, they spontaneously called. When the puppies heard louder sea noises, they lowered their voices. During more intense noise levels, the puppies used a more stable tone – and one seal raised its voice. This behavior, known as the Lombard effect, is typical of human speech when people speak louder to be more understandable, the authors said.
The seals may have lowered their tone as low-frequency sounds travel farther in windy environments like that projected by recorded audio, said Caroline Casey, a researcher and assistant professor at the University of California, at the Santa Cruz Institute of Marine and Ocean Sciences. science department. Casey independently peer reviewed the study, but was not involved in the research.
The results showed that “seal pups have more advanced control over their vocalizations than previously thought,” Ravignani said in a statement. “This control seems to be already present at only (a) a few weeks of age. It’s amazing, as few other mammals seem capable of this.”
Previously, it was believed that humans were the only mammals to have direct neural connections between the cortex – the outer layer of the brain – and the larynx, which we use to produce vocal sound, he added. “These results show that seals may be the most promising species for finding these direct connections and unraveling the mystery of speech.”
By studying what neural networks or social conditions need to be in place for language to evolve, birds have been the best animals we can compare ourselves to, Casey said. This is because in studies of the environment and vocal learning or plasticity, birds – unlike most mammals – can be captive-bred and naturally mature faster due to their short lifespans.
“However, there are many differences, especially when it comes to sociology and the history of life between humans and birds,” she added. “We are always on the lookout for mammals that would be good models for studying vocal learning.”
There haven’t been a lot of studies on how plastic calls from young animals can be. With “most studies, especially in nature, sometimes you don’t know the age or sex of the animals you are recording, so it’s very difficult to get high quality recordings of animals of different classes of animals. ‘age, “Casey added. . “Being able to watch this in this very young age group is very unique.”
Future research, the authors wrote, could further explore what other factors might be important for the vocal plasticity of harbor seals.