Comparative Study Reveals Evolutionary Changes in Language-Related Brain Regions Between Humans and Chimpanzees

Language distinguishes us as humans. While other animals can learn words or calls to communicate, our unique ability to generate an endless array of expressions through a limited set of syntactic rules sets us apart.

A group of researchers, led by Angela Friederici from the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) in Leipzig, in collaboration with scientists from the Universities of Texas and Washington in the United States, has recently published a study in the journal PLOS Biology. Their research directly compared the region of the human brain responsible for language with the corresponding region in chimpanzees using MRI data.

Their findings indicate that the region responsible for syntactic processes in humans has experienced significant expansion in the left hemisphere. This expansion of Broca’s area in the brain throughout evolution may be the foundation of our ability to speak.

At the core of human linguistic capability lies the capacity to apply syntactic rules, determining how words come together to create phrases and sentences. In the human brain, the formation of syntactic structures relies on a sub-region within Broca’s area in the frontal lobe, specifically the inferior frontal cortex. Angela Friederici, Director at MPI CBS, along with Guillermo Gallardo from her team and colleagues from the United States, employed state-of-the-art MRI technology to meticulously map the neuroanatomical details of Broca’s region in both humans and chimpanzees.

Guillermo Gallardo, the lead author of the study, explains the researchers’ initial motivation: “Considering our close genetic and neuroanatomical resemblance to chimpanzees, the critical question was, ‘What biological factors underlie our significant differences in language ability?’ Broca’s area, a region shared with chimpanzees and responsible for syntax in the human brain, emerged as a promising candidate for closer examination.”

To unravel the mysteries of language formation, the researchers utilized advanced algorithms to precisely compare two regions characterized by their tissue composition, denoted as 44 and 45, encompassing Broca’s region in the left and right hemispheres of both human and chimpanzee brains.

Friederici concludes, “Our findings reveal that only area 44 in the left hemisphere expanded in humans compared to chimpanzees. Notably, this specific area is known to be responsible for syntactic processes in humans. We now hypothesize that, during evolution, the enlargement of a specific subpart of Broca’s region, namely brain area 44, may underlie the development of language abilities in humans.”

Source: Max Planck Society

Leave a Comment