“The populations of Finland and Iceland have become valuable resources for geneticists because of their relative isolation. In China, we have several Finlands and several Icelands,” says Lin He, a neuropsychiatric geneticist at the Shanghai Research Centre of Life Sciences.

With the rapid growth of interest in population genetics in recent years, China has become a gold-mine for such studies. Although 93 per cent of Chinese are from a single ethnic group, the Han, the country also has 55 minority groups. Many of them — such as the Tibetans or the Muslim Uyguts in Xinjiang — live in remote border regions.

Through accidents of geography and history, each group has maintained its cultural — and genetic — identity over hundreds, if not thousands, of years. The result is a unique resource that offers vast potential for the study of the genetic basis of human evolution and diseases.

Chinese researchers, backed by foreign colleagues, are developing the skills to exploit these opportunities. The evolutionary studies are already playing a key role in the international Human Genome Diversity Project. And various groups — watched closely by Western pharmaceutical companies — are studying the genetic basis of diseases from asthma to cancer in minority groups in which the incidence is high.

Many Western researchers are also making full use of the genetic variety available to them to study. But as China's economic development leads to the geographical dispersal of minority groups and more intermarriages, the window of opportunity is closing fast.

“With more and more intermingling between different genetic isolates, the conservation of genome samples is an urgent task,” says Zhu Chen, head of the Shanghai Human Genome Centre.

In response, one of the first goals adopted by China's Human Genome Project has been to preserve at least 50 sample genomes from each minority group — as well as genome samples from groups of Han in both the north and south of the country.

Much of this work is concentrated in the south-western province of Yunnan, whose proximity to the foothills of the Himalayas has left it with a wealth of plant, animal and human genetic variety.

Kunming, the capital of the province which boasts 25 ethnic groups, has become a national focal point for the collection of samples through the Institute of Medical Biology of the Chinese Academy of Medical Sciences. “Our key aim is to preserve samples from China's minority groups,” says Chu Jiayou, director of the institute.

Parallel work on conserving genome samples from animals and humans is taking place at the Kunming Institute of Biology, part of the Chinese Academy of Sciences. “This is one of the biodiversity hotspots of the world,” says Ya-Ping Zhang, head of its laboratory of cellular and molecular evolution, which has collected more than 10,000 genetic samples in the past two years alone. “We have to make a big effort to preserve what would be very difficult to regain if it was lost.”