DIETER STEKLIS WAS UNDERSTANDABLY WORRIED last month as he scrambled up the steep, overgrown path to Basumba, a thickly forested hill high among Rwanda's mist-shrouded Virunga volcanos. Just seven months earlier, one of the world's most savage civil wars had devastated the tiny African country. But on this day, Steklis's attention was on a smaller population whose fate was also in question: the world's last mountain gorillas. Although he had been assured by local trackers that the gorillas had survived the carnage, he was determined to be the first scientist to return to the high country to see for himself.

Steklis, 48, director of the Dian Fossey Gorilla Fund, and his wife, Netzin Gerald, 27, a fellow biologist, zigzagged back and forth across the slope, searching for a gorilla family-known as Beetsme's group, a clan of 22 gorillas that had inhabited the range for years. Ankle-deep mud sucked at their boots as they fought their way through shoulder-high thistles and stinging nettles. Suddenly, Steklis spied a telltale swath of trampled vegetation. Signaling his approach with a series of gorilla-like grunts, he edged his way into the clearing. As gorillas lolled nearby, Titus, the 400-pound silverback who is patriarch of his clan, looked up at Steklis with surprise. "I always get emotional when I see them again," said Steklis. "But this year it seems like a miracle."

In many ways, it is. The rare mountain gorillas, whose lives were chronicled—along with that of their original champion, naturalist Dian Fossey—in the 1988 film Gorillas in the Mist, survive in just two isolated habitats: 300 in Uganda's Impenetrable Forest and 300 along the lush slopes of the Virungas that span the borders of Rwanda, Zaire, and Uganda. "They're magical creatures, intelligent, trusting and gentle," says Steklis, who studied them with Gerald at Karisoke (the research center established by Fossey) from 1991 to 1993. "As close primate relatives, they have a lot to teach us about human origins. To lose them would be a disaster."

Amazingly, the gorillas managed to escape the war's slaughter. But the threats to this endangered species may now, ironically, be greater than ever. Land mines and grenades were planted in Rwanda's Volcanos National Park by the Hutu militia as they were routed from the country by Tutsi rebels last summer. (One gorilla, Mkono, was reported killed by a mine in November.) The same Hutu soldiers, now in Zaire, make nightly raids across the border into the park, spraying automatic weapon fire as they poach buffalo and antelope.

Then, too, there are intense new population pressures on the 54-square-mile park. Just two miles away, more than 800,000 refugees are trying to survive in the sprawling camps across the Zaire border. Now, as refugees trickle back into Rwanda, many are traveling through the park with cattle, degrading the habitat and exposing gorillas to upper respiratory diseases to which they have no resistance.

As the war raged last year, Steklis, who is also an anthropology professor at Rutgers University, and Gerald, a graduate student in ecology at Princeton, waited helplessly at their homes in New Jersey. "People would ask me how I could work to save animals amid such enormous human tragedy," he says. "I told them, 'The lives of people and gorillas are intertwined. We needn't compound one tragedy with another.' "

The tragedy began to unfold last April 6, when a plane carrying Rwanda's Hutu president, Juvenal Habyarimana, was shot down. That night, Steklis talked by telephone with Louis Nzeyimana, one of the fund's employees in Kigali. "He told me that killings of government ministers had started," says Steklis. "We knew it would erupt into something terrible."

Few knew how terrible. As extremist members of the majority Hutu militia embarked on a genocidal campaign—butchering minority Tutsis and moderate Hutus over the next four months—Steklis learned that Karisoke's scientific director and three research assistants had evacuated to Zaire; the 31 trackers and rangers bravely remained until July. Then as the Tutsi rebel offensive swept toward them, they, too, ran for their lives, leaving the gorillas behind.

At first, Steklis heard little. In August he made contact with the newly victorious Tutsi-led government and was informed that the fund would be welcomed back to Rwanda—when it was safe. "The motivation may be partly economic," Steklis observes. "Before the war, gorilla tourism provided Rwanda with its third-largest source of foreign income, after coffee and tea. With those crops destroyed [farmers fled from their land, leaving crops unharvested], gorillas have become even more valuable." Whatever the reason, Steklis and Gerald were ready. Entrusting their 11-month-old son, Wulf, to friends, they arrived in Kigali in late January. The city was devastated. Under flowering jacaranda trees, charred hulks of vehicles littered the avenues. Bullet-pitted buildings testified to the summer's fierce fighting. Despite the fund's 16-year presence in the country, not many in the new government, who had spent the last 20-odd years exiled in Uganda and Burundi, knew much about its work. For days, Steklis visited them in their barren offices, introducing the fund anew.

As Steklis made his rounds, he learned firsthand of the war's human toll. Jean Bizimana, one of the few familiar faces left at the Rwandan parks department, told him of the murder of his wife and five children. Alype Nkundiyeremye, a Hutu who was an opposition Member of Parliament and is now the new director of national parks, described fleeing from house to house for three months while the Hutu militia hunted him. "I am alive," he says, "but 25 members of my family are dead."

Steklis and Gerald were apprehensive as they set off for Karisoke on Jan. 31. Accompanied by three soldiers of the Rwandan Patriotic Army toting Kalashnikov assault rifles, they drove north through a countryside that seemed eerily empty. Once-teeming villages had become ghost towns; the fertile terraced fields were overgrown. At the base of the Bisoke volcano, Karisoke's trackers and antipoaching rangers greeted the couple with emotional embraces. "Each of them has a terrible story about family members killed, "says Gerald.

Ascending to an elevation of 10,000 feet, Steklis and Gerald approached Karisoke at dusk. The outlines of cabins were visible in the fading light, but as the two drew closer they saw smashed windows and broken doors. The generator, stove, mattresses—even the sheet-metal roofing—had been looted. That night, as soldiers kept guard at a nearby campfire, Steklis and Gerald lay their sleeping bags on the floor of Fossey's old cabin, one of the few still intact.

"The gorillas. It's the gorillas that get you through," says Steklis. If he speaks of the animals as if they were old friends, they are. Fossey began the study of these very families in 1967, getting 60-odd animals accustomed to the presence of humans. Since Fossey's still-unsolved murder, the fund—which has an annual budget of $1 million, raised from private contributions and charitable donations around the world—has continued to document every aspect of the gorillas' lives, from their eating habits (70 pounds of vegetation a day) to their habitat to their sometimes nearly-human behavior.

Like humans, gorillas display a variety of temperaments. "I remember a period when Pablo really didn't like me," says Steklis. "I think he thought I was competition. Once I was taking notes while watching him, and he came over and tossed me down the hillside." Gerald, too, has had run-ins with moody primates. "Fuddle got really sick of me following her around one day," she says. "She began to chase me around trees and backed me off a little ravine. I was hanging there by my fingertips yelling for Dieter. He came running over and pig-grunted at her like an angry silver-back. She backed off."

At other times, though, the gorillas have seemed to accept Steklis and Gerald as family. In 1992 the two were observing the Beetsme group when soldiers appeared on the trail. "The gorillas crowded around us as if to protect us," says Steklis. "We were part of them. It was extraordinary."

Growing up, Dieter Steklis could scarcely have imagined such extraordinary adventures. Born in Helmstedt, Germany, he moved to El Paso at age 16, when his mother, Hilda, married an American serviceman. Steklis became a star high school wrestler—No. 2 in the state in the 158-pound class—but he was a generally lackluster student. In 1967 he dropped out of the Texas Western College of Mines to move to Oakland with his older brother Detlev. There, while working in a sheet-metal factory, he signed up for a night biology course at Merritt Junior College. "Suddenly I found I had this hunger," he says. "It changed my life."

With straight A's on his transcript, Steklis transferred to the University of California at Berkeley, where he majored in anthropology and from which he received his Ph.D. In graduate school he met renowned neuropsychiatrist Arthur Kling, who invited Steklis to join him in studying primate social behavior.

Steklis, who joined the Rutgers faculty in 1974, went on to become a leading authority on primate brains and neurological bases of social behavior. Then one day he realized that something was missing. "I decided I had a lopsided view of what these animals were about," he says. "I knew them from the inside, but I had no idea where they came from or how they lived. I decided I wanted to study them in their natural habitats."

That same year, 1986, Steklis met Netzin Gerald at the American Society of Primatologists annual meeting in Austin, Texas. A junior at the University of Chicago, Gerald was already an aspiring field biologist. The youngest daughter of archaeologist Rex Gerald and his wife, Elgie, she had grown up accompanying her father to digs. "When I was born, he was working at Chichen Itza [a Mayan ruin on the Yucatan Peninsula of Mexico]," she says. "He named me Nenetzin, which means royal doll in the Mayan dialect."

Their 21-year age difference notwithstanding, Steklis and Gerald were immediately attracted to each other. After a year's correspondence, they began dating. "Netzin is the most honest person I've ever met," says Steklis. "I can't imagine having a better friend or partner." Gerald's assessment of him is equally effusive. "And he likes tequila," she says. "You can't beat that."

In 1988 the couple traveled to the Ishasha Valley of Zaire to do fieldwork on chimpanzees—and to test their own compatibility. "We wanted to see whether we could live in a tent together for three months," says Gerald. They could, and married in 1989. Says Gerald: "We settled in New Jersey, but we knew we'd return to Africa."

In 1991, Steklis accepted a two-year appointment as director at Karisoke. "I don't think Dieter ever imagined protecting mountain gorillas would take these turns," says Peter Clay, Steklis's former assistant at Karisoke, who has just started as the center's interim director. "Wars, revolutions and negotiating with new governments weren't in his contract when he signed on. What he's learned, though, is that no mountain gorillas will survive if Rwandans and non-Rwandans don't work together."

That may be, but the primates are not waiting on the humans. Since last summer, the Karisoke gorillas have produced seven babies. On Steklis's and Gerald's last evening at camp, the Rwandan rangers and trackers invited them to their men's hut for the naming ceremony that has become a tradition. Over urgwagwa, the local banana beer, the men deliberated at length, then announced that only one baby would be named that night. "They're going to call it Wageni," reports Gerald. "It means visitor in Kinyarwanda, the national language." She pauses. "They say it's in honor of our return. They take our presence as a sign of hope."