Goo Goo Ga Ga Gorillas

When confronted with an infant, adult humans are invariably overcome with an irresistible impulse to coo and gurgle to the point of absurdity.  This tendency to modulate vocal inflections to a higher pitch and lilting cadence is universally understood and employed, yet few stop to consider its utility.

The proper term for “baby-talk” (because of course, babies don't actually talk this way, or any way for that matter) is motherese, and it serves a definite function – to simplify the linguistic nuances of adult speech, presenting a minimized version catered to the pre-verbal mind. For example, breaking down complex multi-syllabic words like “water” or “bottle” to “wawa” and “baba” provides a useful preliminary lexicon for beginning speakers. Other common features of baby talk are a slower pace, a gentle crooning intonation, and frequent repetition. 

We've all heard that 90% of communication is non-verbal, and baby-talk is no exception. And it's within the realm of body-language modifications that we find evidence of non-human motherese. Until now, the only evidence of non-human baby-talk was a single modified rhesus macaque call used only when interacting with infant macaques. 

But the Free University of Berlin's Eva Maria Luëf and Katja Liebal have identified a much more complex example of motherese among the captive lowland gorillas they study. These gorillas employ an extensive array of communicative gestures, creating a similar necessity for effective infant assimilation to that found in human communities. By simplifying and repeating gestures, infants can more easily adapt to linguistic norms and integrate into social groups.

The scientists determined that mature gorillas adopted a different array of gestures when playing with infants. As their recent New Scientist article reports, gorillas “encourage play by slapping others while making a "play face," for instance, or somersaulting, and end bouts by placing a hand on the other gorilla's head. With infants, every older gorilla used more touch-based gestures and repeated their gestures more.” 

This compelling evidence leads the scientists to predict that we'll find similar examples of baby-talk in other species of great apes soon. 

"Mother and baby gorilla" by Marieke IJsendoorn-Kuijpers on Flickr courtesy of Creative Commons Licensing.