In December 1929，a Chinese paleoanthropologist named Pei Wenzhong discovered a complete skull of "Peking Man" on Dragon Bone Hill northwest of Zhoukoudian，in the southwest suburbs of Beijing.Later，archaeologists unearthed 40­odd individually fossilized skeletons of "Peking Man"，male，female，old and young，all at the same site.Zhoukoudian，therefore，became the most common site for human remains with the most abundant fossils in the world from the same period.The discovery pushed the history of Beijing's civilization back to some 600，000 years.These fossilized remains prove that "Peking Man" was primitive man in an evolutionary process from ancient ape to modern man，and is the ancestor of the Chinese nation.

　　Inside the 140­meter­long Peking Man Cave，stratum accumulation was of a depth of 40 meters.The inhabitants spanning more than 300，000 years left their remains，stone tools and traces of fire here.On Dragon

　　Bone Hill were also found fossilized remains of Upper Cave Man，who lived 18，000 years ago，as well as sites of New Cave Man，who lived between Peking Man and Upper Cave Man.

　　In 1987，the Zhoukoudian caves were listed as one of the world cultural heritage sites.

　　1．paleoanthropologist n．古人类学者

　　2．unearthed v．发掘

　　3．fossilized adj.化石的

4．stratum accumulation地层堆积