Researchers in France have now identified a unique feature of human brain anatomy that may help to explain how speech emerged. Their work, published in the journal Communications Biology, suggests that our ability to produce such complex vocalizations might be due to subtle modifications of a brain structure we share with other primates.
Many of the brain structures involved in language and speech production are found in the frontal cortex. Céline Amiez of the University of Lyon and her colleagues have previously shown that much of this brain region is organized similarly in Old World monkeys such as baboons and macaques as well as in humans and other nonhuman primates.
Their main finding is that a structure called the prefrontal extent of the frontal operculum (PFOp), which is located within the vlPFC and is fully developed in humans, is only partially developed in chimps and appears to be completely absent in Old World monkeys.
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Importantly, they also found significant variation in the organization of this structure between individual chimpanzee brains, with those having the most human-like PFOp, particularly in the left hemisphere, having greater voluntary control over their larynx and facial muscles.
