Human Temporal Voice Area Lights Up For Chimp Calls
Researchers at the University of Geneva report that parts of the human brain known to process voices respond more strongly to chimpanzee vocalizations than to calls from bonobos or rhesus macaques. The study suggests that some voice-recognition mechanisms in the human brain may extend beyond our species and could predate the emergence of language.
How the Study Was Done
The research team presented 23 human participants with randomized samples of 18 vocalizations from each of four primate species — humans, chimpanzees, bonobos and rhesus macaques. While participants tried to identify which species produced each sound, their brains were scanned with functional MRI. The researchers also analyzed the acoustic features of the calls using statistical modeling to determine how the sounds differed.
Key Findings
The temporal voice area (TVA), including the anterior superior temporal gyrus, showed a stronger and more distinct response to chimpanzee vocalizations than to bonobo or macaque calls. In addition, positive social calls (affiliative sounds) from chimpanzees were found to be acoustically most similar to positive human vocalizations — a similarity not observed for bonobo calls. The authors interpret these results as evidence that certain voice-sensitive processes are conserved across species.
“When participants heard chimpanzee vocalizations, this response was clearly distinct from that triggered by bonobos or macaques,” said Leonardo Ceravolo, co-author and neuroscientist at the University of Geneva.
Where The Recordings Came From
Field recordings included calls from 15 wild chimpanzees in Budongo Forest, Uganda; 10 wild bonobos in Salonga National Park, Democratic Republic of Congo; and 16 rhesus macaques on Cayo Santiago, Puerto Rico. The stimuli set contained single calls and call sequences that covered threat, distress and affiliative social contexts.
Context and Future Directions
Previous studies examined human brain responses to other animal vocalizations, including cats and nonhuman primates, but this study is among the first to document a specific cross-species response within the TVA. The authors suggest future work should isolate the precise acoustic features that make chimp calls more likely to activate the TVA, and explore whether similar sensitivity exists across different human populations and developmental stages.
Bottom line: Echoes of an ancient, cross-species voice-recognition system may still be embedded in the human brain, and chimpanzee calls appear particularly effective at triggering that circuitry.
Originally published on Nautilus.
