“Mamama,” “dadada,” “bababa” – parents usually welcome with enthusiasm the sounds of a baby’s babble. Babbling is the first milestone when learning to speak. All typically developing infants babble, no matter which language they’re learning.
Speech, the oral output of language, requires precise control over the lips, tongue and jaw to produce one of the basic speech subunits: the syllable, like “ba,” “da,” “ma.” Babbling is characterized by universal features – for example, repetition of syllables and use of rhythm. It lets an infant practice and playfully learn how to control their vocal apparatus to correctly produce the desired syllables.
More than anything else, language defines human nature. But its evolutionary origins have puzzled scientists for decades. Investigating the biological foundations of language across species – as I do in bats – is a promising way to gain insights into key features of human language.
I’m a behavioral biologist who has spent many months of 10-hour days sitting in front of bat colonies in Panama and Costa Rica recording the animals’ vocalizations. My colleagues and I have found striking parallels between the babbling produced by these bat pups and that by human infants. Identifying a mammal that shares similar brain structure with human beings and is also capable of vocal imitation may help us understand the cognitive and neuromolecular foundations of vocal learning.
Vocal learning in other animals
Scientists learned a great deal about vocal imitation and vocal development by studying songbirds. They are among the best-known vocal learners, and the learning process of young male songbirds shows interesting parallels to human speech development. Young male songbirds also practice their notes in a practice phase reminiscent of human infant babbling.
However, songbirds and people possess different vocal apparatus – birds vocalize by using a syrinx, humans use a larynx – and their brain architecture differs. So drawing direct conclusions from songbird research for humans is limited.
Luckily, in Central America’s tropical jungle, there’s a mammal that engages in a very conspicuous vocal practice behavior that is strongly reminiscent of human infant babbling: the neotropical greater sac-winged bat, Saccopteryx bilineata. The pups of this small bat, dark-furred with two prominent white wavy stripes on the back, engage in daily babbling behavior during large parts of their development.
Read more: The Conversation