自1929年北京猿人（周口店直立人）第一件头盖骨化石出土以来，迄今周口店遗址5处地点出土了更新世时期的古人类化石，分别为第1地点、第4地点、第15地点、山顶洞和田园洞。基于化石的体质特征及其生存年代，周口店人类化石的演化地位分别被归入直立人、古老型智人（更新世中晚期“非直立人”古老型人类）和早期现代人三个演化阶段。周口店人类化石的发现史大致分为三个时间段：二十世纪二三十年代的大规模发掘期、新中国成立后的恢复发掘和清理期以及二十一世纪新发现。尽管第一时间段发现的人类化石在战争中全部丢失，但聚焦周口店人类化石的研究从未间断，一些热点问题如：北京猿人是否属于隔离人群、是否为东亚现代人的祖先、山顶洞人是否具有蒙古人种特征，等等。在纪念北京猿人第一件头盖发现95周年之际，本文对周口店遗址人类化石的发现历史、标本保存状况、热点问题及其最新研究进展进行了回顾和总结，以期为探讨东亚地区人类的演化提供参考资料。

The Zhoukoudian site is located on Longgu mountain, Zhoukoudian Town, Fangshan district is 48 km southwest of Beijing. The site was discovered in the 1920s, and since the first skullcap of Peking Man was discovered in 1929, 27 paleontological and archaeological localities were found at the Zhoukoudian site(ZKD). Among them, five of the localities yielded Pleistocene human fossils; they are: ZKD-1 (800~ 200 kaBP), Locality 4 (200~ 100 kaBP), ZKD-15 (Late Middle Pleistocene to early Late Pleistocene), Upper Cave (about 30 kaBP) and Tianyuan Cave (about 40 kaBP). The geological age of the sites investigated range from the Middle Pleistocene to the Late Pleistocene, covering more than 500 ka. According to the physical characteristics of the human fossils, the evolutionary status of Zhoukoudian hominids were classified as Homo erectus, archaic Homo sapiens (Middle and Late Pleistocene “non-Homo erectus” archaic humans) or early modern humans. The research at in Zhoukoudian site can be summarized into the following three periods: 1) Large-scale excavation in the 1920s and 1930s with abundant human fossils found at the Locality 1 and Upper Cave. Locality 1 fossils were named as Sinanthropus pekinensis, Peking Man or Zhoukoudian Homo erectus, include five relatively complete crania, more than 150 teeth, several mandibles, and a large number of cranial, facial, and postcranial fragments, totalling about 40 individuals. At Upper Cave, three human skulls, four mandibles plus a few teeth and bone fragmens were found, representing about 7 to 10 individuals. Unfortunately, all the above specimens were lost during the World War II. 2) A period of excavation recovery and site clearing after the founding of the People’s Republic of China in 1949. During this time, 11 human fossils were found at Locality 1. 3) New discoveries in the 21^st century included a human skeleton from Tianyuan Cave, and a human parietal bone was identified among the fragments of mammal fossils at the Zhoukoudian Locality 15.

Over the past years, there continues much discussion about Zhoukoudian such as: Whether the Peking Man has unique or derived features which is not shared by the African and other Asian representatives; whether Peking Man is the direct ancestor of modern populations in East Asia; and whether the Upper Cave Man has Mongoloid characteristics. In recent years, with the new discoveries and the innovative research methods, further questions dealing with survival adaptations and genetic structure have been asked. In commemoration of the 95^th anniversary of the discovery of the first Peking Man skullcap, this paper reviews and summarizes the history, research topics and research progress of work discovery at Zhoukoudian Site, in order to provide reference for the discussion of human evolution in East Asia.