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Dolphins use baby talk when communicating with calves, study finds

It appears baby talk is not just for human babies. 

Bottlenose dolphins use motherese, commonly known as baby talk, when speaking to their calves, according to a study published Monday in the journal Proceedings of the National Academy of Sciences. A team of scientists found mother dolphins change the tone of their signature whistles, unique whistles carrying identity information, when addressing their babies. 

"Our data provide an example of convergent evolution of motherese in a nonhuman mammal and support the hypothesis that motherese can facilitate vocal learning and bonding in nonhumans as well as humans," the researchers wrote.

A new study shows that humans are not the only mammals to use motherese with their offspring. Bottlenose dolphins also modify their communication with their calves. Photo taken under NMFS MMPA Permit No. 20455 issued to the Sarasota Dolphin Research Program.

The researchers analyzed recordings of 19 adult female dolphins during brief catch-and-release events near Sarasota Bay, Florida. They'd temporarily outfitted the dolphins with hydrophones attached to each dolphin's head with suction cups.

The whistles they recorded showed the sounds used to address babies have "significantly higher maximum frequencies and wider frequency ranges." 

The usage of child-directed communication is believed to enhance attention, bonding and vocal learning, but researchers said they're not sure what the "mechanistic driver(s) or function(s) of" baby talk is for bottlenose dolphins.

"It has been well documented that dolphins are capable of vocal production learning, which is a key aspect of human communication," journal article co-lead author Nicole El Haddad said. "This study adds new evidence regarding similarities between dolphins and humans."

Calves spend up to six years with their mothers, according to the National Oceanic and Atmospheric Administration. When young, they maintain a "baby position" and keep close to their mothers.

Researchers noted there is evidence of child-directed communication in other species, including female greater sac-winged bats and adult male zebra finches

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