Long arcuate fascicle in wild and captive chimpanzees as a potential structural precursor of the language network

Abstract The arcuate fascicle (AF) is the main fibre tract in the brain for human language. It connects frontal and temporal language areas in the superior and middle temporal gyrus (MTG). The AF’s connection to the MTG was considered unique to humans and has influenced theories of the evolution of...

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Main Authors: Yannick Becker, Cornelius Eichner, Michael Paquette, Christian Bock, Cédric Girard-Buttoz, Carsten Jäger, Tobias Gräßle, Tobias Deschner, EBC Consortium, Philipp Gunz, Roman M. Wittig, Catherine Crockford, Angela D. Friederici, Alfred Anwander
Format: Article
Language:English
Published: Nature Portfolio 2025-05-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-59254-8
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Summary:Abstract The arcuate fascicle (AF) is the main fibre tract in the brain for human language. It connects frontal and temporal language areas in the superior and middle temporal gyrus (MTG). The AF’s connection to the MTG was considered unique to humans and has influenced theories of the evolution of language. Here, using high-resolution diffusion MRI of post-mortem brains, we demonstrate that both wild and captive chimpanzees have a direct AF connection into the MTG, albeit weaker than in humans. This finding challenges the notion of a strictly human-specific AF morphology and suggests that language-related neural specialisation in humans likely evolved through gradual evolutionary strengthening of a pre-existing connection, rather than arising de novo. It is likely that this neural architecture supporting complex communication was already present in the last common ancestor of hominins and chimpanzees 7 million years ago, enabling the evolution of language processes in the human lineage.
ISSN:2041-1723