Researchers have discovered that the origin of human language dates back 20 million years farther than what was previously realized.
According to a study led by Newcastle University, the human language pathway appeared in the brain at least 25 million years ago.
“It is like finding a new fossil of a long lost ancestor,” said study lead author Professor Chris Petkov. “It is also exciting that there may be an older origin yet to be discovered still.”
Scientists had previously found evidence to suggest that the precursor of the language pathway emerged about five million years ago in the brain of a common ancestor of humans and apes.
To gain insight into the evolution of the human brain, neuroscientists use brain imaging techniques to compare the brains of primates and humans.
For the Newcastle study, an international team of experts analyzed the auditory regions and pathways in brain scans from humans, apes, and monkeys.
The team discovered a segment of the language pathway in the human brain that connects the auditory cortex with frontal lobe regions, where important speech and language processes take place. The auditory pathway was present in the nonhuman primates as well, indicating this brain network was the evolutionary basis of auditory cognition and vocal communication.
“We predicted but could not know for sure whether the human language pathway may have had an evolutionary basis in the auditory system of nonhuman primates,” said Professor Petkov. “I admit we were astounded to see a similar pathway hiding in plain sight within the auditory system of nonhuman primates.”
The research is shedding new light on the remarkable transformation of the human language pathway. A key difference was found among humans in which the left side of the brain pathway was stronger. The right side appears to have diverged to involve non-auditory parts of the brain.
The study authors predict that the origin of the human language pathway is even older, and future research may find new evidence in animals that are more distantly related to humans.
“This discovery has tremendous potential for understanding which aspects of human auditory cognition and language can be studied with animal models in ways not possible with humans and apes,” said study senior author Professor Timothy Griffiths. “The study has already inspired new research underway including with neurology patients.”
The research is published in the journal Nature Neuroscience.