Phytolith evidence for human-plant subsistence in Yahuai Cave(Guangxi, South China) over the past 30000 years

South China preserves a rich archaeological record elucidating the evolution of early modern humans during the Late Pleistocene.However,few studies on plant utilization were conducted in this region.We used phytolith analysis from Yahuai Cave,Guangxi,to infer human use of plant resources over the past 30000 years.AMS 14C dating was used to constrain the chronological framework.Results indicate that several economically essential species were present throughout the sequence including Urticineae(cf.Ulmus sp.),which appears in the lower layers of the sequence(Marine Isotope Stage 3 through Heinrich 1);bamboo and palm which appear throughout the sequence,and wild rice which appears in a clear archaeological context dating to 16000 years ago.This is the earliest record of wild rice in South China and a prerequisite for rice domestication.The unique stone tool assemblages,which resemble those in north China as opposed to South China,point to the possibility that humans,seeking refuge from the colder north,brought their tool kit with them and utilized familiar northern taxa.Warmer South China would have served as a refuge for human populations escaping the cold,harsh climate in the north with more ameliorate conditions in the south.