Prehistoric dregs pack a punch
Residues on Chinese pots give earliest direct evidence of brewing.
The inhabitants of China appreciated a tipple as much as 9,000 years ago, according to an analysis of pottery shards from the period. Chemical residues reveal that the pots were used to hold a drink made with rice, honey and fruit, and are the earliest direct evidence for brewed beverages.
Throughout history, human societies have used the process of fermentation to create alcoholic drinks. But how this practice first evolved has remained elusive.
In some areas, ancient texts provide clues. The oldest surviving recipe in the world comes from a 3,800-year-old clay tablet of Sumer, a civilization from the area that is now southern Iraq. Part of a hymn to the goddess of brewing gives details about how to make beer.
Oracle inscriptions dating back China's late Shang dynasty (about 1200-1046 BC) also describe alcoholic beverages.
Experts believe that fermented drinks probably existed in China and elsewhere much more than 3,000 years ago. But until now they have relied only on the shape and styles of pottery vessels to support this idea.
Patrick McGovern at the University of Pennsylvania Museum of Archaeology and Anthropology in Philadelphia and his colleagues hoped to find direct chemical evidence of fermentation. So they examined 9,000-year-old pottery shards from 16 vessels belonging to an early Neolithic village in what is now eastern China.
The fragments came primarily from the bases of these vessels, which absorb more liquid and collect more precipitates than the container walls. The team used a range of chemical tests, including infrared spectrometry, to detect tell-tale substances on the surface of the clay. They report their results online in the Proceedings of the National Academy of Sciences1.
The strongest clue was the presence of tartaric acid, the principal organic acid in grape wine, which gives evidence that the drink was fermented, says McGovern. Tartaric acid is accepted as a reliable marker for wine, says Joseph Lambert, an archaeological chemist from Northwestern University in Chicago.
"Once you've determined that you've got tartaric acid, then you're on firm ground," he says.
The shards seem to have beeswax residues on them, and grape and hawthorn seeds were also found at the site. The chemical analysis also showed similarities with results from rice wines made today.
So the researchers believe that the fermented beverage involved a mix of rice, honey and fruit. The flavour of either hawthorn or grape probably dominated the drink, says McGovern.
But it is the age of the site that makes these findings so sweet. "This is the earliest chemical evidence for fermented beverages that we have from anywhere in the world," says McGovern. "It shows that fermented beverages have a much earlier history and importance in the development of human culture than has often been assumed."
McGovern believes that the Chinese were not necessarily the first to discover the secrets of brewing. As scientists use similar techniques to analyse samples from the Middle East, he predicts that the production of barley beer there will be found to go back at least as early as developments in China.
- McGovern P., et al. PNAS, doi:10.1073/pnas.0407921102 (2004).