Typically, archaeological research into the origins of agriculture has focused on western Asia, in areas such as the Fertile Crescent (the present-day Middle East). Now scientists report that intentional collection of grass seeds may be traced back about 30,000 years in China, about the same time similar practices occurred in Europe and western Asia.

As the human lineage evolved, so too did the ways it made use of plants, says study lead author Can Wang at the Key Laboratory of Cenozoic Geology and Environment in Beijing. During the Lower Paleolithic, which started about 2.5 million years ago and is marked by some of the earliest signs of human stone tool construction, ancient humans gathered plants randomly. However, during the Middle Paleolithic, starting about 300,000 years ago, there is evidence that ancient humans began focusing on certain plants, such as those with nutritious tubers and roots. Then, during the Upper Paleolithic, beginning about 50,000 years ago, human use of edible plants became markedly sophisticated, evolving from foraging to farming.

Wang and his colleagues systematically compiled an archaeobotanical database of China of plant remains dating between roughly 30,000 and 5,000 years ago. This data came from 127 species, including fruits, nuts, beans, yams, and cereals such as millets and rice.

The findings indicate that peoples from northern and southern China used markedly different plants, probably because of differing climates—for instance, northern China used more beans, roots and tubers than southern China did during the Upper Paleolithic. The scientists relied on data from 84 archaeological sites, 74 of which were located in northern China and 10 of which were located in southern China.

Seeds from wild grasses were intentionally collected in both northern and southern China starting about 33,000 years ago, much as they were in Europe and western Asia during about this time. These wild grasses were apparently staple foods, along with beans, tubers, roots, especially in northern China.

“The transitional process to agriculture in China was slow and long-term,” Wang says. The scientists detailed their findings online February 3 in the journal PLOS ONE.

China’s climate gradually began warming 14,000 to 9,000 years ago during the transitional phase from the Paleolithic to the Neolithic. The scientists noted that in northern China people were intentionally cultivating millet and were starting to domesticate it while in southern China people were intentionally cultivating rice. By the Early Neolithic 9,000 to 6,000 years ago, the climate in China was warm and wet, northern China had domesticated millet, and southern China had begun domesticating rice. During the Middle Neolithic 6,000 to 5,000 years ago, millet farming completely dominated subsistence practices in northern China, and rice farming was dominant in southern China.

All in all, the researchers concluded that the transition to rice and millet agriculture in China was a slow process spanning tens of thousands of years. They suggested this shift might be analogous to the development of wheat and barley farming in western Asia.

The researchers suggested that one possible explanation for this increasing use of grass seeds during the Upper Paleolithic was a cold, dry climate. As the human population grew, previous food resources were insufficient, “and then people had to expand their diet, including intentional collection of grass seed,” Wang says.

Future research might focus on why different regions of China cultivated the plants that they did, says archaeologist Robert Bettinger at the University of California, Davis, who did not take part in this research. For example, in northeast China, people domesticated millet for their own diet, Bettinger says, while in western China, people domesticated millet as dog feed, and the canines then helped people hunt wild pigs. “Dogs don’t like eating plant matter,” Bettinger notes. “But they’ll do it.”