Baboons show handedness in communicative gestures, tending to be right-handed. This paper analyzed the handedness of baboons to see if they were more likely to use their right or their left hands for communication.
Here is a key figure.
We know that there is a connection between handedness and the lateralization of language in humans. Humans are primarily right-handed, and the vast majority of right-handed people have their language functions lateralized to their left hemisphere. Left-handed people -- though the distinction is not as clear cut -- also usually show language function in primarily in the left hemisphere. Chimps also show handedness for motor tasks.
The authors argue that data suggests that language emerged from a lateralized cortex for motor gestures:
From a comparative viewpoint, regarding our results and the literature, we suggest the existence of a continuity between asymmetries of speech related gestures and asymmetries of communicative gestures in chimpanzees and now in baboons, even though the degree of population-level right-handedness is lower in non-human primates than in humans. From an evolutionary viewpoint, we suggest that the neuroanatomical substrate of manual communication controlled by the left cerebral hemisphere may have existed in their common ancestor at least 30 million years ago and may be considered as the precursor of the human language area. Our results hence bring additional support to the view that lateralization for language in humans may have evolved from a gestural system of communication lateralized in the left hemisphere.
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