The gelada monkey, found only in the highlands of Ethiopia, is known as the bleeding heart baboon for the splash of red on its chest. Males of the species have a remarkable vocal agility greater than that of any nonhuman primate.
Geladas have the largest canine-to-body-size ratio of any mammal. And those fangs are not used for eating.
Geladas live in massive social groups of up to 1,000 monkeys.
"They're smacking their lips together, they're changing their face — their facial structure — and they're vocalizing at the same time," says Morgan Gustison, a doctoral candidate and researcher with the University of Michigan Gelada Project.
So the monkey can vocalize, but is it saying anything? Gustison hopes to find out. With the help of a Young Explorers grant from the National Geographic Society, she's been going back and forth with her tape recorder to the University of Michigan gelada research site in the Simien Mountains National Park.
To research geladas, just drive into one of their habitats in the Ethiopian highlands and get out of your car. You'll find hundreds of them out in the open hills munching on grass.
They hang together in such large groups that even researchers who spend all day with the monkeys for months at a time need to code each family with letter names just to keep track of the shifting alliances.
"The J's and the K's and the D's are usually together with the V's," researcher Marcela Benitez says from her vantage point near a mountain peak. She points out different monkey families in what looks to this reporter like an indistinguishable sea of fur. "But now the D's are up there on the hill, the V's are by themselves up here, and the others are down there with the N's and the J's, which usually hang out with the M's and the A's."
Life Without Pecking Order
This fluid social order is one of the most distinctive aspects of gelada society, and one that might unlock the key to their distinctive verbal agility. Socially speaking, geladas are like the urbanites of the primate world — always bumping into strangers. "And that's actually really rare," Benitez says. "For most nonhuman primates, you know every single person in your group."
She says most nonhuman primates live in the social equivalent of the smallest of small towns, where you know everybody, and everybody knows you. There's a pecking order. Geladas, by contrast, live in massive social groups of up to 1,000 monkeys. When group size gets that large, hierarchy breaks down. So, one of the theories these scientists are testing is that geladas' vocal agility might have arisen from the necessity to quickly win over friends and allies in a crowd of strangers, like a guy on a soapbox on a street corner.
The peaceful scene of grass-chewing monkeys one encounters on an early-morning arrival doesn't remain peaceful for long. Geladas have the longest canines per body length of any mammal, and they're not used for eating. In their daily life, conflict is simmering just under the surface. Gelada males are polygamous; one male has many females, which leaves many frustrated unattached bachelors sending threatening calls and screams from the fringes.
"I call them frat boys," Benitez says, laughing. "They look hungover, they spend a lot of time together, and then all of a sudden they decide they're going to cause problems. And everyone's afraid of them, and no one wants them around."
Complicating this ritual machismo, geladas are a female-choice society, where the females decide whom to accept or rebuff.
It's a swirl of domestic drama where fights are bound to occur, and when they do, Gustison is ready with her tape recorder. Why? Because, she says, just after a disruption of the social order is when male geladas give voice to some of their most complex strings of sound, perhaps as a way of quickly restoring relationships. "The gelada may be saying something like, 'everything's all right, I'm cool, I'm not hurt,' " says Gustison, "basically calming down the situation."
Most primates achieve this emotional bonding with physical grooming. Gustison says geladas are capable of "vocal grooming." She compares it to being thrown into a cocktail party with lots of people you barely know. The specific meaning of the words you're speaking may not be as important as the relationships you're trying to build. Indeed, "vocal grooming" may suggest something about how our earliest ancestors evolved the ability to speak.
The Big Role Of Small Talk
"It broadens our ideas about the origins of language," Gustison says. Because while much research has focused on the referential side of language, she says, language is just as much about shoring up relationships as it is about expressing information.
"I'll get off the phone with my mother, and I can't remember half the things I say, but I do know that I remember whether or not it was good conversation," Gustison says. "So we want to see besides the semantics what else is important about complex vocal communication that could be a precursor to language."
Long before our early ancestors ever formed sentences, she says, we might have been limbering up our lips, throats and tongues to send each other sounds of comfort, warning and encouragement, like we do now with babies before they learn to talk.
Under that theory, Gustison says, early man's first attempts to speak might have aimed less to describe the outside world, than simply to make that world somewhat less frightening and less lonely.