Archaeologists believe pottery was invented by the people of ancient Japan some 16,000 years ago. But production was slow until the end the ice age. Around 11,500 years ago, the amount of pottery made by ancient hunter-gatherers rose dramatically.

For many years, researchers have debated the cause of the uptick in pottery production. Previously, scientists pointed to the changing climate as an essential factor, but new research suggests cultural changes were responsible for the increase.

The predominant theory has been that a warming climate and the return of woodlands made new food sources available. As a result, ancient Japanese peoples developed new techniques for cooking, processing and storing new food items. The thinking goes that their shifting eating habits demanded new pottery.

To test this theory, an international team of researchers analyzed 143 ceramic vessels from Torihama, an archaeological site in western Japan. The vessels span a 9,000-year time period.

Scientists subjected lipids extracted from the ancient vessels to molecular and isotopic analysis in order to determine the types of food being cooked and stored over time. The findings suggest the types of food being eaten from and stored in pottery remained relatively stable. Even as the climate warmed, the hunter gatherers subsisted mostly on marine and freshwater animal species -- fish and shellfish.

The research results, detailed in the journal PNAS, suggest the uptick in pottery production was the result of cultural changes, not environmental ones.

"Here, we are starting to acquire some idea of why pottery was invented and became such a successful technology," researcher Oliver Craig, an archaeologist at York University in England, said in a press release. "Interestingly, the reason seems to be little to do with subsistence and more to do with the adoption of a cultural tradition, linked to celebratory occasions and competitive feasting, especially involving the preparation of fish and shellfish."

"The endurance of this transition means it was embedded in East Asian foragers' social memory for hundreds of generations, perhaps reflecting the need for a dependable method to exploit a sustainable food in an uncertain and changing world," Craig added.