Babies, and some of the rest of us in our less proud moments, are not alone in speaking this way.
According to a study published today in PeerJ
, bonobos communicate similarly to human infants, which means "baby talk" may not be uniquely human.
"It appears that the more we look, the more similarity we find between animals and humans," said Zanna Clay of the University of Birmingham's School of Psychology, who led the study.
Bonobos, humanity's closest relatives, have a reputation for being talkative. They are known to blow raspberries to get attention. Some of the most well-known bonobos seem to understand English. They can identify words based on symbols or even manage to use an iPad.
But very frequently, bonobos "peep," keeping their mouths closed and letting out a quick, high-pitched sound. They do it in a variety of contexts, whether they have found food or something much less welcoming. If that sounds to you like the way human infants squeak and growl, well, some scientists agree with you.
To explore bonobo peeps, Clay led a group of researchers to record a wild bonobo community in the Democratic Republic of Congo. They observed the community of some 39 apes and recorded the peeps, cataloging what the bonobos were doing and what was going on around them during each peep.
"When I studied the bonobos in their native setting in Congo, I was struck by how frequent their peeps were, and how many different contexts they produce them in," Clay said. "It became apparent that because we couldn't always differentiate between peeps, we needed [to] understand the context to get to the root of their communication."
They found that in positive contexts, like eating, and neutral contexts, like traveling or resting, the peeps sounded basically alike. In negative contexts, like alarm at the discovery of a predator, peeps varied widely.
According to the study, the observations suggest bonobos can communicate a range of emotions with the same sound. This kind of speech is called "functional flexibility," as opposed to "functionally fixed" communication, like crying, screaming and laughing, which depends on emotion. Until now, researchers thought "functional flexibility" was something only humans had.
The findings help researchers learn more about bonobos -- and more about us. If "functional flexibility" is not uniquely human, further study of bonobos might help us uncover a range of mysteries, from the way human speech evolved to the role of speech in biological processes. Who knows? We might even get a comprehensive understanding of baby talk.
The study also calls for further research of bonobo peeps to confirm these findings and hopefully learn more about the way our closest relatives speak.
Bonobos have long since exhibited emotions we know not to be uniquely human. The apes laugh and scream. They play, and they form deep communities. According to this study, it looks like they also speak with weird little noises, conveying the important information a child is able to communicate to a parent.