The oldest chemical evidence of an alcoholic beverage dates back to about 7000 BC inside pottery jars excavated at Jiahu, an early Neolithic village in the Yellow River Valley, Henan province, China. The residues could be identified as alcoholic beverages as they contained chemical compounds characteristic of some fruits and of the wines made from them. Specifically, the compounds were tartaric acid (from grape and hawthorn tree fruit), very specific beeswax compounds (from honey) and phytosterol ferulate esters (from rice). This indicated that the liquid inside the vessels was a mixture of rice beer, honey mead and hawthorn and/or grape wine.The findings indicate that fermented beverages were already being made about 9,000 years ago. The discovery was made by Prof. Patrick McGovern, a molecular archaeologist from the University of Pennsylvania Museum of Archaeology and Anthropology and lead author of the study "Fermented Beverages of Pre- and Proto-Historic China" published online in the journal Proceedings of the National Academy of Sciences (PNAS) on 8 December 2004, and colleagues from institutions in the USA, China and Germany.