Parents often use a high-pitched or sing-song voice to talk to their babies. As it turns out, humans aren’t the only ones in the animal kingdom to adapt the pitch of their voice to communicate with their offspring: according to new research, dolphins do the same.
Laela Sayigh, associate professor of animal behaviour at Hampshire College in Massachusetts, and her colleagues have been studying how dolphins address their young.
Biologists have known for decades that these mammals have a complex, structured communication system. They produce social sounds to “talk” to one another, as well as echolocation clicks to hunt and orient themselves in their environment.
It might, therefore, be logical to assume that these animals could emit unique whistling sounds when communicating with their offspring.
To verify this hypothesis, researchers analysed the whistling sounds of around 20 bottlenose dolphins in the waters around Sarasota Bay, Florida. These were recorded over a period of 34 years, when the females were with or without their young.
The team found that the females produced whistles of higher frequency and pitch when addressing their pups. They also use a much wider range of frequencies in this situation, the researchers explained in their paper published in the journal PNAS.
This study provides further proof of the richness and versatility of animal language. Indeed, many animals speak differently to their babies than to their peers – rhesus macaques and squirrel monkeys make unusual sounds, including grunts and nasal moans known as “girneys”, to attract the attention of the young of their species.
Researchers from the University of Chicago even concluded in 2007 that these language behaviours were an example of “baby talk”, or “motherese” in scientific jargon.
So is “baby talk” a universal language, transcending both borders and species? There’s no way of knowing, since it’s difficult to demonstrate that a concept exists in the mind of an animal.
But this dolphin discovery could help us better understand the evolutionary history of vocal learning in animals and, perhaps, even in humans.