The sounds and screeches that come from a gelada’s vocal chords are so complex that Researcher Morgan Gustison, a doctoral candidate with the University of Michigan Gelada Project, believes they give clues about the origins of human speech. Nicknamed the “bleeding heart baboon” because of its crimson chest, the gelada lives in large tribes made up of thousands of monkeys in Ethiopia’s Simien Mountains National Park, the only place the gelada resides. While other baboon species live in smaller societies, the size of the geladas’ tribes means that they have to negotiate more complex social situations. Scientists are unsure of the exact meaning of the gelada sounds, but their research and observations show that those sounds are meant to communicate and form alliances.
Language is not just about communicating information, but also about forming relationships, Gustison tells NPR.  The gelada society is a tense one. Males are polygamous, but it is the female who decides which male she chooses. Males who are not chosen let out frustrated cries and screams. Because of the size of the group, the social order often shifts, and geladas are constantly negotiating various alliances among the thousands in their group. In other monkey groups like the savanna baboons the hierarchy doesn’t alter nearly as much as in the gelada society, and so fights don’t occur as often. After fights have finished, geladas express their most complex vocal sounds, Gustison explains. She suggests that this might be a way of calming down or restoring relationships.
The complex vocal sounds of geladas share some important characteristics with the way human babies utter pre-language sounds, says Gutison. Babies don’t use precise words to communicate what they want or need, but adults can easily distinguish between a cry for help and one of joy. Words can be used to express a precise thought, but sometimes multiple words or certain sounds can be adequate in expressing oneself.
Thore Bergman of the University of Michigan’s Department of Psychology and Ecology & Evolutionary Biology explains to WIRED how the complex sounds provide some insight into the origins of language. Either humans were already able to voice complex sounds and wanted to attribute various meanings to those sounds in order to better communicate, or words evolved out of a necessity for improved communication. Both possibilities suggest a need for communication, and in a society where voices are competing over each other for attention, vocal interactions are quite important.
Speaking up to be heard is not a new concept in larger societies, since it is nearly impossible to hear every individual voice. Geladas use elaborate sounds to speak, and this discovery probes people to think about how human vocal sounds might have evolved to attribute meaning, resulting in the sophisticated vocabulary used today.
Photo: Marta Semu