CHONGZUO, China: Long ago, in the poverty-stricken hills of southern China, a village banished its children to the forest to feed on wild fruits and leaves. Years later, when food supplies improved, the children's parents returned to the woods to reclaim their young. To their surprise, their offspring had adapted to forest life remarkably well: The children's white headdresses had dissolved into fur, tails grew from their spines and they refused to come home. At the Nongguan Nature Reserve in Chongzuo, in Guangxi Province, the real-life descendants of these mythical children - monkeys known as white-headed langurs - still swing through the forest canopy. As the langurs traverse a towering karst peak, in a setting out of a Chinese landscape painting, they appear untouched by time and change, but it is remarkable that they and their tropical forest home have survived. In 1996, when the langurs were highly endangered, China's premier panda biologist, Pan Wenshi, came to study them in Chongzuo, at what was then an abandoned military base. This was at a time when hunters were taking young canary-yellow langurs from their cliff-face strongholds, and villagers were leveling the forest for firewood. Pan quickly hired wardens to protect the remaining animals but then went a step further, taking on the larger social and economic factors jeopardizing the species. Pan believed that alleviating the region's continuing poverty was essential for their long-term survival. In the 24-square-kilometer, or 9.2-square-mile, nature reserve where he has focused his studies, Pan found the langur population has increased to more than 500 today from 96 in 1996. "It's a model of what can be done in hot-spot areas that have been devastated by development," said Russell Mittermeier, the president of Conservation International. "Pan has combined all the elements - protection, research, ecotourism, good relations with the local community. He's really turned the langur into a flagship for the region." Part of what makes Pan's achievements so remarkable is the success he is having compared with the fate of primates elsewhere. According to the most recent Red List, the roster of threatened species compiled by the International Union for Conservation of Nature, nearly half of the world's 634 primate species and subspecies are in danger of extinction. "If you look at the Red List, Asia has by far the highest percentage in the threatened categories," Mittermeier said. When Pan arrived in Guangxi, the challenges of studying langurs, much less protecting them, seemed insurmountable. He and a student spent their first two years living in collapsing cinder-block barracks without electricity or running water. At that time, the langurs' population was in free fall, dropping from an estimated 2,000 in the late 1980s to fewer than 500 a decade later. Local farmers had occasionally killed langurs for food, but then teams of outside hunters began taking a serious toll on the population. "In the 1990s, the Chinese economy started booming, and those with money - governors, factory owners, businessmen - all wanted to eat the wildlife to show how powerful they were," said Pan, 71. A breakthrough in protecting the species came in 1997, when Pan helped local villagers build a pipeline to secure clean drinking water. Shortly thereafter, a farmer from the village freed a trapped langur and brought it to Pan. "When you help the villagers, they would like to help you back," he said. As a self-appointed local advocate, Pan raised money for a new school in another village, oversaw the construction of health clinics in two neighboring towns and organized physical exams for women throughout the area. "Now, when outsiders try to trap langurs," Pan said, "the locals stop them from coming in." But the villagers were still dependent on the reserve's trees for fuel. "If I told them they can't cut down the trees, that wouldn't be right," Pan said. "They have to feed their families." In 2000, he received a $12,500 environmental award from Ford, the American automaker. He used the money to build biogas digesters - concrete-lined pits that capture methane from animal waste - to provide cooking fuel for roughly 1,000 people. Based on the project's success, the federal government financed a sevenfold increase in the construction of tanks to hold biogas. Today, 95 percent of the population living just outside the reserve burn biogas in their homes. As a result, the park's number and diversity of trees - the langurs' primary habitat and sole food source - has increased significantly. "When I first came, the hillsides were very rocky," Pan said. "Now it's hard to see the rocks and even harder to see the langurs because of all the trees." Nearly all the money for Pan's development projects has come from outside the region, but his efforts have not gone unnoticed by local officials. In 2001, the county government built a research center in the reserve with accommodations for Pan and his students, a guesthouse and a yet-to-be completed education center to showcase the region's biodiversity. Still, those who would like to exploit the scenic beauty of the park remain. One recent proposal included a five-star hotel that would turn the education center into a gambling hall and cockfighting pavilion. In 2002, when Pan inaugurated the Chongzuo Ecology Park, a small part of the Nongguan Nature Reserve that is open to the public, he had a quote from the ancient Chinese philosopher Mencius carved into stone at the front gate. The phrase was a subtle reminder to local officials that the park should not be misused for their own financial gain: "In an ideal society, everyone should work for the well-being of others." But the quote also reminds those looking to protect the langurs that they must consider the area's human community. "This is the most important thing we can do," Pan said. "If the villagers can't feed themselves, the langurs don't stand a chance."