Although he is just over the age of 60, biologist and photographer Yin Kaipu has seen the difference a century can make.The photographer spent six years retracing the steps of British botanist Ernest Henry Wilson, crisscrossing China from 2004 to 2009 to take pictures at the same sites Wilson visited about 100 years previous.Yin took four trips to Chongqing municipality and central China's Hubei province during the period, as well as ten trips within south China's Sichuan province.

"The total distance adds up to tens of thousands of kilometers," he said.The pictures Yin took during his travels were published two years ago in "Tracing One Hundred Years of Change," a collection of photos taken by both Yin and Wilson at precisely the same locations, albeit one century apart. Yin, a researcher at the Chengdu Institute of Biology (CIB) under the Chinese Academy of Sciences, was inspired to undertake the project in 1997, when one of his colleagues showed him "Chinese Wilson," a book of photos taken by Wilson during his travels in west China.Yin was already familiar with Wilson's work, having used his book "Plantas Wilsonianae" as a reference while conducting botanical research in south China's Sichuan province. Yin was pleased to recognize many of the areas depicted in "Chinese Wilson," having traveled to many of the same areas in west China.

However, Yin also realized that many things had changed since Wilson's travels to China in the late 19th and early 20th centuries."What if I were to follow his route and take the same pictures at the same sites?" Yin asked himself. Having already traveled a great deal and become knowledgeable about photography through his own work, Yin felt he was prepared to undertake the task.in began by collecting as many of Wilson's photos as he could find. He received some from his friends at the British Royal Botanic Gardens, an organization that launched a cooperative program with the CIB in 1989. Another friend provided him with another of Wilson's books, which contained more photos.

Still more photos were purchased from Harvard University, where Wilson worked in his later years, while a photo-collecting friend working in the tourism industry provided Yin with even more shots. However, after selecting 400 of Wilson's photos to imitate, Yin realized that the scope of his project might be too vast.Yin was approaching retirement age at the time, and had no hope of acquiring funding from the CIB to support his endeavor. He paid his travel costs out-of-pocket in the beginning, raising funds through other means later.

Locating the actual sites where the photos were taken also proved to be more difficult than anticipated. Wilson gave little information about the places he shot, using vague English translations of Chinese names for the places he did write about. Using recognizable landmarks to identify the locations was rarely helpful, as many of them had disappeared in the ensuing 100 years.Regardless, Yin did his best to retrace Wilson's travels, making educated guesses and carefully studying all of Wilson's works. Many of the locations were in remote mountain areas, and Yin was forced to combat storms, floods, landslides and other natural disasters in his attempt to recreate Wilson's photography.

Yin's age didn't help, either. Wilson was in his 20s when he first came to China. He was well-funded, well-equipped and accompanied by a score of aides. Yin, on the other hand, was approaching retirement and often had just one or two people traveling with him during his journey."The revisits were not easy," Yin said.