Two decades of trailblazing advances in science and technology have transformed the restoration and preservation of cultural relics. Once a traditional handicraft it has grown into a scientifically based discipline in its own right.

On March 29, 1974 farmers from Xiyang village at the northern foot of Mt. Lishan set out to dig a well. What they did that day was to put Xi'an in Shaanxi Province forever on the world map. They found the famous Qin Dynasty terracotta warriors and their horses patiently frozen in time for some 2,200 years. And so the 'eighth wonder of the world' once again saw the light of day.

When large-scale excavations began in 1978 archaeologists brought with them the taxing question of how best to preserve literally thousands of priceless historic treasures.

So far just over 1,000 terracotta warriors have been renovated but some 7,000 more are still waiting in line for attention. Taking the old rule of thumb of one expert piecing together one terracotta warrior per month using traditional methods, the project would still have had another century to run.

But today thanks to a computer based 3-D restoration system developed by the Institute of Visualization at the Department of Computer Sciences at Xi'an-based Northwest University, it takes just hours to reassemble the jigsaw puzzle that is a terracotta warrior. And so the long buried Qin Dynasty legion can pull itself together and be on the march again within a couple of years.

A technique jointly developed by Chinese and foreign experts has brought improvements in stabilization and resistance to shrinkage. This has helped solve the earlier difficulties that had plagued color restoration on the terracotta warriors and horses. At last the old warriors can look like themselves again as they stand guard in the Museum of the Qin Terracotta Warriors and Horses in Xi'an.

Digital technology has been applied to the study of mummies to reveal how individual people once looked in real life long ago.

Zhao Chengwen is a professor with the Chinese Police Criminal Institute based in Shenyang city, Liaoning Province. Using his own specialist computer software coupled with X-ray studies of the skull he has been able to reconstruct the facial features of a 2,200 year old beauty as she would have looked at 18, 30 and 50 years of age.

Her well preserved body was excavated at Mawangdui in Changsha city, Hunan Province. She is believed to be the famous Xin Zhui, wife of a chief minister of the Changsha Kingdom under the Western Han Dynasty. Legend has her involved in a love triangle with her husband and the monarch.

Researchers at the Changchun-based Jilin University have successfully used 3-D technology to simulate the original appearance of two 1,000-year-old mummies that were unearthed in Turpan in the Xinjiang Uygur Autonomous Region. Advanced molecular biology techniques are being applied to research on the body of a woman found in a Western Han tomb at the Laoshan site in the suburbs of Beijing. The work will add to the body of knowledge on DNA and the human physique in antiquity. In fact, Jilin University has successfully investigated human bones brought to light in Xinjiang, Inner Mongolia, Qinghai and northeast China. It has built up a DNA bank for ancient Chinese people living on the frontiers of empire.

The 1987 excavation of the Tang Dynasty terrestrial palace within the Famen Temple found in Fufeng County, Shaanxi Province produced over 700 fabric relics. Textile techniques like printing, appliqui and gold lining went into the making of the royal dresses which featured such varied fabrics as brocade, damask, satin, carbaso, yarn, gauze etc.

A 15-year multidisciplinary study brought together experts in archaeology, meteorology, spinning and weaving. It identified effective methods for eradicating mildew and restoring lost moisture content in ancient fabrics. Much has been learned about the conservation of textiles under ideal conditions of constant temperature and humidity. The work enabled delicate silk treasures from the Tang Dynasty to be put on public display for the first time in July 2002.

In 1995 a remarkable discovery was made in Guangrao County, Shandong Province. An adult male skull dating back 5,000 years was uncovered at a site of the Dawenkou Culture. Careful scientific examination of this Neolithic skull showed that a craniotomy had been performed during the lifetime of its owner. Used in the treatment of head trauma this is a surgical procedure in which a flap of scalp and bone is opened in the skull. The use of the technique in antiquity was already known but the Dawenkou discovery pushed its earliest date back a further 1,000 years.

Developments in technique have led to many successes in the restoration of China's cultural relics including the:

• renovation of the Dunhuang frescoes in Gansu Province

• restoration of copper chariots from the Qin Shihuang Mausoleum (tomb of the first emperor of the Qin Dynasty) in Xi'an

• reproduction of bronze chiming bells from the tomb of Marquis Yi of the Warring States Period in Suizhou city, Hubei Province

• restoration of water damaged bamboo and wooden slips

• restoration of excavated rusted ironware

• preservation of ancient buried bronze ware

(China.org.cn, translated by Shao Da, June 22, 2003)