The Peking Man discovery is celebrated as a major step forward in the theory of human origin and evolution. The discovery of the community of at least 40 hominids, among the first pre-human fossils found in Asia, revolutionised science by showing that half a million years ago a creature similar to modern man - originally labelled Sinanthropus pekinensis, Peking Man, and later incorporated into the species Homo erectus - could handle fire, engage in creative behaviour, use tools, develop cultural aspects of their society including funeral rituals, and hunt large mammals. It marked the evolutionary stepping stone palaeontologists had been looking for as it showed that Homo erectus was different from the ape in physical characteristics and cranial capacity and therefore occupied the middle phase in the evolution from ape to Homo sapiens, or modern man. The Zhoukoudian caves, widely considered to be the most intact Homo erectus dwelling in the world, were opened in 1921 and the first Homo erectus remains were uncovered in 1929. Over a decade, about 40 individuals were uncovered, but everything mysteriously vanished during the second world war and have never resurfaced. The fossil remains had been on display at a museum in Beijing but were taken by United States Marines in December 1941 at the end of the four-year Sino-Japanese War, according to mainland media reports. They were intended to be shipped back to the US, but the marines were attacked by the Japanese and the specimens were lost. There is now only one known Peking Man bone fragment on the mainland, a jaw bone, which is kept in the Chinese Academy of Sciences in Beijing. China's leading scientists have launched several unsuccessful appeals for clues to the whereabouts of the missing remains.