Abstract: More than 50 years ago, in his publications on human fossils from Zhoukoudian Locality 1, Weidenreich argued that the difference in size of Sinanthropus teeth is a sexual one(Weidenreich, 1935) and the large type of teeth belong to male individuals and the small to females" (Weidenreich, 1937). He concluded :"The mor phological character of the Sinanthropuspopulation of Locality 1, therefore, remained unchanged during the long periodsof timenecessaryfor the fillig-up of the cave (Weidenreich, 1935).
In this paper, a comparison of the teeth from upper layers with those from loweronesshows that a temporal variation is also responsible for the difference in size of the teeth fromthis site. The temporal variation can be seen in mandibular teeth. Over the timespan from 500to 230 Ky B.P, the lower incisors tend to be larger whereas the lower canines and postcaninesto be smaller. The P, reduces less than the P,, and the M; reduces less thanthe other molars.An evolutionary change in direction of early Homo sapiens conditionis suggestedin thedental sample from Zhoukoudian Locality l.

Key words: Tooth; Variation; Zhoukoudian