| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
|
|
|
here at the academy Charting China's MonkeysWhen Nina Jablonski arrived at her first teaching post at the University of Hong Kong in 1981, Asia was an open book to her. She soon found that its chapters on primate evolution and diversity remained largely unwritten. So Jablonski, now Irvine Chair and Curator of Anthropology at the Academy, tapped into a rich source for research that kept her in Asia, intellectually, even as subsequent jobs took her to Australia and ultimately to San Francisco. One of the most geologically dynamic parts of the planet, eastern Asia has been dramatically affected by environmental change for the last 50 million years--ever since India collided with the southern side of Asia and compressed the continent like an accordion. The incredible pressure elevated the towering Himalayan peaks and the vast Tibetan Plateau. By 2.5 million years ago, the plateau had risen high enough to redirect atmospheric circulation and create the modern cycle of monsoons. The resulting cool, dry climate transformed Asia: deserts grew, tropical forests shrunk, and ice sheets covered China's northeast corner. As environments became increasingly fragmented and unpredictably seasonal, animals had to adapt or perish. China preserves the most complete record in Asia of what transpired in the last two million years, so Jablonski launched an ongoing project to gather basic data on how the distribution of mammals changed with the environment. Her goal is to understand how their biology constrained these mammals' evolutionary courses, sending many to extinction while permitting some to survive and thrive. As an anthropologist, her attention focuses on the primates: monkeys, apes, Homo erectus, and early members of our species. The responses of apes and monkeys to change differed like night from day. Apes stayed shackled to diminishing rainforests where they could obtain enough fruits and protein to fuel their larger bodies and brains. For many, the shift toward seasonality sounded a death knell; the orangutan, for instance, once occurred across Asia but now clings to existence on Borneo and Sumatra. "What had been a land with a diverse range of apes in it all of a sudden becomes almost ape-free," says Jablonski. "Monkeys always have existed as ecological jacks-of-all- trades," she continues. They can make do with lower quality diets, mature earlier, and give birth more frequently than apes. In short, monkeys were poised to take advantage of seasonal climates. As a living example of how monkeys adapted to dramatically different lifestyles, Jablonski cites the Yunnan snub-nosed monkey (Rhinopithecus bieti), which moved into high-altitude pine forests where its most consistent sources of food are hanging moss pulled from the trees and lichens scraped from rocks. Working closely with Chinese biologists and paleontologists, Jablonski uses donated Silicon Graphics work stations and Geographic Information Systems (GIS) software provided by the Environmental Systems Research Institute to create a series of digital maps of China, on which different habitat and vegetation types and paleotopographic features will be overlain along with fossil localities for over 400 mammal species. The project will compile the first ever paleoecological database for Asian mammals, but more importantly for Jablonski, GIS provides a powerful tool for studying how the life history of species evolved as their environments changed. Once all the information is in place, Jablonski can carry out statistical analyses to examine where certain groups survived, whether they overlapped, and how they responded to climatic shifts. Ultimately, Jablonski's database will dig deeper into the past, as far back as 20 million years ago in the Miocene. She also plans to add information about the distribution and natural history of living mammals, which could lead to developing guidelines to conserve certain species. The period of biggest environmental change in Asia coincided with the appearance and evolution of human ancestors there. Just how and where hominid populations emerged as modern humans remains a topic of sharp debate, but Jablonski believes that her analysis of what environmental barriers existed in Asia will provide the various competing hypotheses with a geographic reality check. What she can say is that in the last 100,000 years, humans excelled in their ability to occupy areas off-limits to all other primates. Previously intolerable places could be colonized and environmental barriers overcome. Near the end of the Pleistocene 15,000 years ago, after the Last Glacial Maximum eliminated what little remained of China's tropical refuges, says Jablonski, "you see humans who have essentially surmounted their [apelike] life history parameters." We know how humans ultimately fared. As for the monkeys, a more moderate climate in the last 10,000 years allowed them to rapidly expand their range and diversity in China. Jablonski has been studying how the macaques flourished at this time, but she maintains her affection for the colorful snub-nosed monkeys and has edited a book on The Natural History of the Douc and Snub-nosed Langurs that will be published next year. Aside from her research, Jablonski's first two years at the Academy have been marked by enthusiasm for programs that educate the public about anthropology. She is particularly excited about next April's Wattis Symposium, third in a series that has already covered hominid systematics and prehistoric art. The next topic, "The Origin and Diversification of Language," she says, unites all the often fragmented fields within anthropology. The symposium brings together prominent international researchers to eschew controversy in favor of collaboration toward discovering some hard data that might shine light on this elusive subject--an approach personified by Jablonski herself. Blake Edgar is Associate Editor of California Wild. |
Winter 1997
|
