Flakes of charred material scraped from shards of ancient pots are the earliest direct evidence of pottery use for cooking, a new study suggests. Possibly the biggest surprise, scientists say, is that these prehistoric chefs weren't part of an early agricultural community, and they weren't cooking grain: They were hunter-gatherers who lived in Japan during the waning phases of the last ice age, and they were apparently boiling up a seafood stew.
Pottery was invented somewhere in eastern Asia between 12,000 and 20,000 years ago, but exactly where and when—and particularly why—isn't clear. Indeed, virtually nothing is known about how the first pots were used, says Oliver Craig, a biomolecular archaeologist at the University of York in the United Kingdom. Regardless of why such vessels were invented, they undoubtedly offered new and attractive ways to process and consume food, he notes. Layers of blackened material on the inner surfaces of some pot shards, many of them palm-sized or smaller, hinted that the vessels had been used for cooking, but scientists hadn't performed detailed studies to confirm the notion.
So Craig and his colleagues analyzed small samples of charred material taken from 101 ceramic vessels or fragments found at 13 sites spanning the length of Japan. In previous studies, researchers had dated the sites to between 11,200 years and 15,300 years ago, an interval that archaeologists call the Incipient Jōmon period. (In Japanese, jōmon means cord-marked, a distinctive feature of the pottery produced by the Jōmon people, the prehistoric inhabitants of the Japanese islands.) Most of the sites are inland near rivers or lakes, and at the time they were occupied they would have been even farther from the coasts than they are today, because sea levels were lower.
First, the team looked at the ratios of carbon and nitrogen isotopes in the charred scrapings. Although the ratios varied widely, the nitrogen isotope ratios in more than 75% of the samples suggested that the pots had been used to cook aquatic creatures, most likely fish, at or near the top level of their food chain. Detailed analyses of larger samples taken from 57 pots and shards at two of the sites revealed that nearly one-third of the scrapings included fatty acids, which typically derive from oils naturally found in freshwater and sea-dwelling organisms such as fish and marine mammals, the researchers report online today in Nature. Such substances result only from the oils' prolonged exposure to high temperature—a strong sign that the vessels had been used for cooking, Craig says.
The shapes of the pot fragments suggest that most of the vessels had volumes between 1 and 4 liters, he says. It's possible that the Japanese hunter-gatherers were cooking fish, shellfish, or even marine mammals caught along the coast. However, considering that the sites were some distance inland, it's also possible that the itinerants were catching and cooking migratory fish such as salmon, which spend much of their lives in the sea and then swim upstream to spawn.
The new findings are starting to broaden the view of late ice age hunters, once thought of as chiefly chasing big game such as mammoths, says Simon Kaner, an archaeologist at the University of East Anglia in Norwich, U.K. "This suggests they were exploiting a range of resources," he notes, possibly including some that were available only during certain seasons.
The techniques used by Craig and his team should now be used to analyze other samples of early pottery, Kaner says. That might shed light on the factors that influenced the development and spread of pottery, which dramatically expanded after the ice age ended a little less than 12,000 years ago. "We're just at the beginning of this, exploring what was going on with early societies."