We will also stream this seminar via Zoom.

Catherine Crockford
Great Ape Social Mind Lab
Institut de Sciences Cognitives Marc Jeannerod
CNRS

The patterning and ontogeny of chimpanzee vocal sequences – and brain pathways

A striking feature of the human species is our large brain, enabling some complex skills that surpass those of other species, such as tool use, social cognition, and in particular, language. The question of how the brain pathways supporting these skills evolved across phylogeny is still open, mainly due to a lack of studies directly comparing human and non-human primate brains and the related behaviour. In a consortium, the Evolution of Brain Connectivity Project, we first examine the structure of vocal sequences emitted by wild chimpanzees (Tai Chimpanzee Project, Ivory Coast), in adults and through ontogeny, and then examine a developmental sample of post mortem wild, zoo and sanctuary chimpanzee brains sourced after natural death. Across 46 adults and including around 5,000 utterances, we found that the vocal sequences show positional and transitional properties, suggesting that permutation relationships exist between the calls. Vocal sequences were used extensively across the repertoire such that their flexibility exceeds that reported for old world monkeys, with implications for predictions for target regions of white-matter tracts across species. Using 10,000 vocalisations from 98 chimpanzees throughout chimpanzee ontogeny, we found that ordered call sequences emerged after two years of age and continued to increase in complexity until around 8 years of age, with implications for the development of relevant brain pathways. I will briefly mention preliminary work examining chimpanzee brain pathways. We are initially focusing on the dorsal tract, a white matter tract considered crucial for language in humans. Our preliminary developmental tractography results suggest a strengthening of the dorsal tract connecting the inferior frontal lobe with the temporal/parietal regions with age. We point out similarities and differences in the dorsal tract across chimpanzees and humans and discuss the implications of these findings for the evolution of language.

Pizza will be served. Please bring your own beverage!