Researchers find brain regions linked to hand preference and language evolution in baboons

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A recent study led by CNRS scientists investigated the connection between brain anatomy and hand preference for communication in newborn baboons. The researchers focused on the planum temporale (PT), a brain region associated with language in humans and also significant in baboons. They discovered that about 70% of newborn baboons exhibited early asymmetry in the PT, with the left hemisphere being larger. This brain asymmetry was linked to a right-hand preference for gestural communication as the baboons matured. This preference for communication gestures differed from their handedness in non-communicative actions like food manipulation.

Conversely, the remaining 30% of baboons, which either showed no PT asymmetry or had right-sided asymmetry, did not exhibit a consistent hand preference for communication. This suggests that PT asymmetry plays a role in the development of gestural communication in humans and monkeys, hinting at an evolutionary trait shared with a common ancestor from 25 million years ago.

The study's conclusions were based on behavioural observations of baboons, previously assessed for brain asymmetry using MRI scans at birth. This research enhances our understanding of the evolution of gesture and language in primates and may have clinical implications for brain surgery. It could help determine the dominant hemisphere for language by analyzing simple communicative gestures, potentially reducing the risk of post-operative language impairments.