National Geographic : 2017 Apr
0mi 100 0km 100 Average length (male) 2 feet Gelada Olive baboon GreatRiftValley Ras Dejen 14,928 ft 4,550 m ETHIOPIAN HIGHLANDS Addis Ababa Debre Birhan Mekele Gonder Bahir Dar Dessie Mehal Meda Asela ETHIOPIA SUDANETHIOPIA YEMEN DJIBOUTI ERITREAETHIOPIA Menz-Guassa Community Conservation Area Simien Mts. National Park Lake Tana Awash Red Sea BlueNile AFRICA AREA ENLARGED ETHIOPIA Gelada range 80 national geographic • april 2017 scampering geladas crossed the road, the small- est doing rhythmic half cartwheels. One landed on a rock 10 feet away. His eyes clocked us as we passed. A hay-colored mane spilled down his shoulders. His arms and fists appeared stuffed in black evening gloves. He looked almost regal. Geladas, one of the flagship species of Africa’s alpine grasslands, are found only in the Ethiopian Highlands. They are the smallest vestige of a genus that millions of years ago stretched from South Africa to Spain and into India. Once among the most prominent primates—one species was the size of a gorilla—they were likely driven to extinc- tion by climate changes, competition with more adaptable baboons, and our ancestors, who butch- ered them. Today all that remains of Theropithecus are geladas, which offer valuable, if imperfect, in- sight into the world inhabited by our predeces- sors. There is no other animal like them. Hours after arriving at the research camp—sev - en tents, a rarely used bucket shower, and a mud- dy tepee that serves as a guard shack—Kerby and I set off. We walked past a hidden camera trap. Six- ty-five monkeys sat in a meadow. The air smelled of thyme. The monkeys didn’t look up as we wad- ed through. A baby sprawled on its back, one adult grooming its face, another stroking its leg. “ That kid’s getting the deluxe treatment,” Kerby joked. Geladas’ most recognizable features are crim- son patches of hairless skin on their chests. In females, this region changes color, and tiny sacs around its edge fill with fluid, often indicating that they are ready to mate. The pink on domi- nant males darkens to red. Other primates signal sexual readiness with their rumps, but these mon- keys spend most of the day scooting on their rears, gorging. Most primates climb trees to eat fruit and leaves. Geladas use opposable thumbs to pluck grass blades and herbs. Like zebras, they mince food with their molars. In theory, Kerby said, “primates shouldn’t eat grass.” From a nutrition- al standpoint, grass holds little energy. Getting enough takes work and time. Such inefficiency would have made it hard to fuel the evolution of a big brain. That might explain why geladas are less curious than, say, Botswana’s chacma ba- boons when shown dolls or rubber balls. But that doesn’t mean these monkeys aren’t crafty. Kerby and I squatted and listened. The air filled with squeaky chewing. One animal emit- ted a guttural seagull honk. I heard shrieks as if from squabbling crows. A female grunted “Uh, uh, uh,” which Kerby said roughly translates to “ Yo dude, I’m right here.” Geladas form roving primate cities, arranging themselves in herds of several hundred. They communicate using one of the largest vocal repertoires of any nonhuman primate. Their lip-smacking “wobble” may even offer evidence that facial noises were a precur- sor to human speech. To document behavior and family dynamics, researchers give geladas mem- orable aliases. That can make life on the plateau seem at times like a daytime soap opera. Tiny Astral, for example, is known for starting fights, swiping at larger monkeys, then ducking behind her mom, Autumn, like a spoiled mean girl. Lydia isn’t the best mother to Lobelia, so Lydia’s sister, Lox, often steps in. When Lydia abandons her offspring, which is often, Lox lets Lobelia hitch rides on her back. Five Dollar Foot- long (named for a sandwich) once stood on hind legs with arms outstretched as if desperate for a hug. Instead, his mother, Frodo, slapped him. Females form a sisterhood, moving in repro- ductive units with one or a few males. Geladas aren’t monogamous, so male-on-male encounters are often fraught. Take Reverend Lovejoy. When this leader, named for a preacher on the televi- sion show The Simpsons, spied a rival’s infant in rich grass, he screamed. He flapped his eyelids and flipped up his lips. He bared impressive dag- gerlike canines. Geladas don’t use these teeth for hunting. They’re for display and fighting. Rev- erend Lovejoy raced to scare the youngster, but then his rival swooped in. They faced off, inches apart, huffing, until the rival backed down. Guassa researchers, from Ethiopia and abroad, have followed the minutiae of the daily life of almost 500 individuals. They monitor activity, study relationships, track births, and document deaths. While studying responses to dying, they n Society Grants Your National Geographic Society membership helped fund this photography.