The UNIGE team wanted to find out whether the frontal and orbitofrontal regions of our brain activate in the same way when faced with human and simian vocalizations. Image Credit: © Leonardo Ceravolo |
Are we able to differentiate between the vocal emissions of certain primates? A team from the University of Geneva (UNIGE) asked volunteers to categorize the vocalizations of three species of great apes (Hominidae) and humans. During each exposure to these "onomatopoeia", brain activity was measured. Unlike previous studies, the scientists reveal that phylogenetic proximity - or kinship - is not the only factor influencing our ability to identify these sounds. Acoustic proximity - the type of frequencies emitted - is also a determining factor. These results show how the human brain has evolved to process the vocal emissions of some of our closest cousins more efficiently. Find out more in the journal Cerebral Cortex Communications.
Our ability to process verbal language is not based solely on semantics, i.e. the meaning and combination of linguistic units. Other parameters come into play, such as prosody, which includes pauses, accentuation and intonation. Affective bursts - "Aaaah!" or ‘‘Oh!’’ for example - are also part of this, and we share these with our primate cousins. They contribute to the meaning and understanding of our vocal communications.
When such a vocal message is emitted, these sounds are processed by the frontal and orbitofrontal regions of our brain. The function of these two areas is, among other things, to integrate sensory and contextual information leading to a decision. Are they activated in the same way when we are exposed to the emotional vocalizations of our close cousins, the chimpanzees, macaques and bonobos? Are we able to differentiate between them?