The human ability to comprehend words and gestures originate in the same regions of the brain, says an upcoming study.
Researchers have shown that the brain regions that have long been recognized as a center in which spoken or written words are decoded are also important in interpreting wordless gestures.
The findings suggest that these brain regions may play a much broader role in the interpretation of symbols than researchers have thought and, for this reason, could be the evolutionary starting point from which language originated.
"In babies, the ability to communicate through gestures precedes spoken language, and you can predict a child's language skills based on the repertoire of his or her gestures during those early months," said James F. Battey, Jr., M.D., Ph.D., director of the National Institute on Deafness and Other Communication Disorders (NIDCD), one of the National Institutes of Health.
"These findings not only provide compelling evidence regarding where language may have come from, they help explain the interplay that exists between language and gesture as children develop their language skills," he added.
Scientists have known that sign language is largely processed in the same regions of the brain as spoken language. These regions include the inferior frontal gyrus, or Broca's area, in the front left side of the brain, and the posterior temporal region, commonly referred to as Wernicke's area, toward the back left side of the brain.
It isn't surprising that signed and spoken language activate the same brain regions, because sign language operates in the same way as spoken language does-with its own vocabulary and rules of grammar.
In this study, the researchers, in collaboration with scientists from Hofstra University School of Medicine, Hempstead, N.Y., and San Diego State University, wanted to find out if non-language-related gestures-the hand and body movements we use that convey meaning on their own, without having to be translated into specific words or phrases-are processed in the same regions of the brain as language is.
The researchers found that for the gesture and spoken language stimuli, the brain was highly activated in the inferior frontal and posterior temporal areas, the long-recognized language regions of the brain.
The study has been published in this week's Early Edition of Proceedings of the National Academy of Sciences (PNAS).