Researchers have discovered that some monkeys process the sounds of other monkeys in their brains much like the way people process language. As this ScienCentral News video reports, it's a discovery that may lead to a better understanding of how people acquired the ability to communicate.
We've all seen primates when they are monkeying around. But how much actual communicating is going on?
"[Monkeys] do communicate vocally," says John Roden, Curator of Animals at the Central Park Zoo. "They definitely have different vocalizations that they'll do, that I would say have a communicative role in their interactions. If they are startled, they might make a loud vocalization that would alert the group that there's potential danger around. They have smaller vocalizations, if they find a food source or something like that, that they might want to share with others. It's not necessarily as complex, obviously, as human vocalization, but it certainly does convey information."
Amy Poremba, a psychologist at the University of Iowa, wanted to learn more about what goes on in monkeys' brains when they communicate. She and her team used positron emission tomography (PET) to scan the brains of eight healthy rhesus monkeys as they listened to the calls of other monkeys and other sounds. "We played a number of different sounds to the animals," says Poremba, "including human voices, which we thought they might very active to because they hear a lot of human voices, and environmental sounds such as running water, bells ringing, tones being played and also other animal calls."Poremba found that monkeys process their calls with the left side of their brains, the same part we use when we listen to human speech. "Only when they listened to the monkey calls did we see this left hemisphere more active than right hemisphere," she says. "So it seemed to be very specific for their communication types of sounds such as language processing in the humans. When you play monkey calls in particular, their particular communication sounds, then you get something that looks very similar to the human's. You get more activation, more energy use on the left hemisphere than the right, matching the pattern that’s normally shown in humans."
Scientists have known for a while that people process speech on the left side of their brains, but weren't sure about primates. Because the patterns are so similar to the patterns in people's brains when we respond to language, Poremba thinks the sounds monkeys make could be the precursors, or building blocks, of human language. "This might give us a model at least of communication and that would lead up to possibly being able to study the rudimentary or the very basic processes that we need to start putting together language skills," she says.
Poremba hopes her research will lead to better understanding of how to treat learning disabilities associated with communication problems. "Lots of [people with] learning disabilities…have problems with hearing things. They maybe mis-hear, or they have trouble reading, or they have trouble speaking or comprehending. So one of the things that we're interested in doing is looking at the basic systems. We have to know the basic information…to be able to start to solve some of these more difficult problems in humans. Learning disabilities, schizophrenia, autism, these all deal with communication problems and so we want to start to get the basics."
This research appeared in the January 29, 2004 issue of Nature and was funded by the National Institute of Mental Health and the University of Iowa.