A LANGUR FAMILY: A white-headed langur family in their natural habitat (XINHUA)
After a loud blast set off by villagers quarrying stones, a white-headed langur popped its head out of the tree canopy at the foot of a towering limestone cliff. Its eyes seemed to be filled with terror and sadness.
It was the first time that Pan Wenshi, a Peking University biology professor, saw a langur. It was November 1996 and he was completing field studies in south China's Guangxi Zhuang Autonomous Region. At that time, there were no more than 100 white-headed langurs still alive in the world, Pan recalled.
Conservation International and the Primate Specialist Group of the International Union for Conservation of Nature have listed the species as one of the world's 25 most endangered primates. White-headed langurs have lived on Earth for more than 3 million years, but the population has been dwindling due to habitat destruction and poaching.
Guangxi is home to the extremely rare species. Generations of white-headed langurs have leaped and swung along the forested cliffs of Guangxi's karst hills. They are born with canary yellow furs that turn black when they mature, while their head hair and moustaches turn snow white.
Pan said it is sad that human factors are jeopardizing the species. He feels it is the duty of scientists to protect them from extinction, and he decided to do something to save the langurs.
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Pan and his students roamed the hills to study the monkeys. They lived in tents or slept in caves before settling into a deserted army camp. Venomous snakes constantly threatened them. They set out before dawn every day into the wildness, carrying telescopes to observe the animals.
Pan's research went smoothly with help from the local government and Peking University, and in October 2000 the university's Chongzuo Biodiversity Research Base was created. At an international meeting in August 2002, Pan revealed that his group had discerned the breeding pattern and evolutionary history of the langurs after six years of research.
Pan also studied the langurs' social behavior. He found that the species are polygamous, taking on more than one mate at a time. He observed adult males fighting for breeding rights. The stronger males take the loser's mates and become the family's head. Younger and stronger males, however, continuously challenge the dominant male's position.
In some cases, winners of the battle for dominance mercilessly kill newborns fathered by the losers by pushing them off cliffs, Pan found. The killings were intended to induce mothers to have babies of the winner sooner.
But not all battles for dominance result in infanticide. Pan observed that some males negotiate and divide females and territory without killing newborns. Pan said that negotiating is an evolutionarily more advantageous strategy.
Pan also found that although male monkeys usually leave their parents' side to start their own families after growing up, some choose to stay to help the father defend the home territory and take care of the siblings. These altruist males keep the monkey families and society more stable.