Shards of pottery dating back 18,000 years have been unearthed in a cave in Hunan province, southern China.The manufacture of ceramic pots and other items is generally associated with the change from Paleolithic hunter-gatherer societies into sedentary Neolithic communities, which began about 10,000 years ago in the eastern Mediterranean.But dating finds from these sites have proved challenging.The complex layers of ash, clay and gravel make the sites difficult to analyse and it has been hard to find pure samples of organic material such as charcoal and bone for carbon dating.The latter date also matched that of the layer of sediment in which the shards were found.In a new study, physicist Elisabetta Boaretto of the Weizmann Institute of Science in Rehovot, Israel, and archaeologist Xiaohong Wu of Peking University in Beijing and their colleagues show that humans were making containers out of fired clay even earlier than was previously thought.
But pottery manufacture began considerably earlier in East Asia, during the late Paleolithic.
Until now, the earliest previous finds in East Asia were dated to 15,000–16,000 years ago.
"In environments in which there is a lot of ash, charcoal doesn't preserve well, and throughout China there are deposits of windborne dust that contain a lot of calcite, an element of wood ash," explains Boaretto's colleague Steve Weiner, of the Kimmel Center for Archeological Science at the Weizmann Institute.
Normally, an excavation project would seek to date as many carbon samples as possible, explains Boaretto.
By carefully analysing the layers of earth around the pottery shards to note any disturbances — for example, fire hearths and animal burrows — the team could determine which carbon samples were most closely related to the pottery finds.
The team's carbon dating suggests charcoal and bone samples obtained from the site are 21,000 to 13,800 years old, whereas those located just above and below the pottery shards are about 18,000 years old.