MIDDLE PLEISTOCENE CLIMATE AND HABITAT CHANGE RECORDED IN FOSSIL HERBIVORE TEETH FROM THE PEKING MAN SITE

The Peking Man Site at Zhoukoudian, located about 50km to the southwest of Beijing, is of great significance in human evolution studies, as fossil evidence indicates the occupation of the area by our ancestors for the majority of the last 500,000 years. The fractionation of isotopes in the enamel of herbivore molars, found abundantly within sedimentary deposits at the site, can be of use to paleontologists and anthropologists attempting to piece together the paleoenvironment in which Peking Man, New Cave Man, and Upper Cave Man lived. Here we use the carbon and oxygen isotope compositions of tooth enamel from several herbivores to determine the ratio of C3 and C4 pathway plants in the diet of these species and reconstruct the paleoenvironment at the site.

Samples analyzed in this study date between 570,000 ya and 250,000 ya, roughly encompassing the time period during which Peking Man inhabited the location. Of the three species for which we presently have data, Equus sanmeniensis shows the greatest range in d¹³C, with values varying from those of a predominantly C4 diet to a pure C3 diet (-3.5‰ to -11.2 ‰). Megaceros pachyosteus shows less d¹³C variation, with values characteristic of a pure C3 diet (-11.0‰ to -13.5‰). Samples of Dicerorhinus choukoutienensis are all from the same stratum dated at ~570,000 ya and have d¹³C values ranging from -10.2 to -12.8‰, indicating that they were feeding predominantly on C3 plans at that time. These preliminary data suggest that there were both C3 and C4 plants in the area during the middle Pleistocene, and the variation in the diet of herbivores examined here is primarily due to feeding preference of the species. The d¹⁸0 values of tooth enamel from the same species also show large variations with time, indicating changes in climatic conditions in the area. Future analyses will include a larger variety of species and a greater span of time.