Curling his upper lip and flashing a set of shiny white teeth, the gelada baboon snatched another bite of grass and watched his harem dive over the cliff face.
The entire clan of a dozen monkeys tumbled over the edge, performing cartwheels and landing on a rock ledge where they would hide for the night from an approaching hail and thunderstorm.
High on the Ethiopian plateau, the geladas - technically monkeys - graze on grass and farming crops and try to keep their distance from humans. But as farms increasingly eat up grasslands, and the pollutants used by humans raise the earth's temperature, the gelada is increasingly threatened, say experts who have studied them for the past five years.
Primate expert Chadden Hunter compares the plight of the gelada to someone "sitting on the roof top and watching the flood waters rise.
"Our research suggests that for each 2 degrees C (3.6 F.) degree increase in temperature, the gelada's lower limit for grazing will rise 500 meters [547 yards]," he says. "Global temperatures only need to rise a few degrees, and they will be, in effect, lifted off the top of the mountains."
As global temperatures increase, treelines and vegetation profiles, including the sensitive alpine grass that the gelada feed on, diminish. A Swiss study of the Ethiopian highlands has shown that the specific grasses that the monkeys feed on have receded steadily upward over the past several hundred years.
A separate study commissioned by the World Wide Fund for Nature cited the gelada last year as one of several mammals most at risk from the effects of global warming. The list also includes the mountain pygmy possum of Australia.
American and Ethiopian primate experts concur that temperature shifts may soon destroy the high-altitude "islands of grass" on which the gelada thrive. "Since the gelada survive at the physical limits of the landscape, the likelihood of future global warming raises serious questions over the species' survival," says Jacinta Beehner, an American baboon expert with long experience in Ethiopia.
Theropithecus gelada is the last species remaining of a genus of a terrestrial primate. Mr. Hunter believes that the graminivorous (grass-eating) monkeys may have lost most of their close relatives to past bouts with global warming. "They are the last relic of a great dynasty, barely surviving in the Ethiopian highlands," he says.
On the hillsides beside one of the country's 14th-century Christian monasteries, dozens of gelada bawl and yelp out some of their 30 distinct calls, complex vocalizations that primate experts say closely resemble those of their human relatives.
The gelada, which scamper and leap through the highlands in "herds" of 600 or more, maintain a complex social structure that offers irreplaceable insight into human social behavior, say Hunter and Beehner.
Older males, with long manes and bushy tails, spend the day with small clans of females, many with babies perched on their tiny backs. The harem-owning males abide by their own etiquette, however, of never stealing one another's wives. Gangs of young males keep their distance from the harems, cautiously waiting in the wings with an eye to enticing the females away when their day to own a clan arrives.
"Gelada males struggle to remain 'lord of the manor' when their families extend beyond about five females," says Hunter, currently in Liverpool, England. "When aging males inevitably fail to attend to the steady demands of their females, the younger sharks move in to steal the show."
Even if man is able to stabilize the effect of global warming on the gelada habitat, some Ethiopian experts believe an equal threat to their survival comes from the struggle with man for living space.
"The most immediate threat to the gelada's survival comes from farming," says Tesfaye Hundessa, the manager of Ethiopian Wildlife Conservation Organization. "They could well be entirely eliminated by humans before the global warming has time to take its toll over the coming decades. Unfortunately, they don't make congenial pets."
Oromo tribesmen use the lionlike mane of the male geladas as a headdress in their centuries-old warrior dance. "But the gelada that the locals kill for their furs are far fewer than the ones shot dead by farmers angry that the beasts have been grazing on their barley and wheat," adds Mr. Hundessa. "Our law gives these farmers the right to protect their crops from wild animals with whatever means necessary."
Hundessa says that the law could well be amended if the gelada population, currently estimated at 100,000, continues to diminish.
(c) Copyright 2001. The Christian Science Monitor