Rice

Rice began as a wild grass of wet ground, Oryza rufipogon, which grows across the tropics and subtropics of Asia. 3,418,3 It comes in two forms: a tall perennial, and a short annual that some botanists count as a separate species, Oryza nivara. 107,1818

It is a hard plant to harvest. It sprawls along the ground. Its grains fall as they ripen, each one armed with a long barbed awn, and the grain inside is red. 108109110,111112,9

Long before anyone farmed it, wild rice had split into separate lineages. The two that lead to today's indica and japonica rice parted hundreds of thousands of years ago.20,3,9

The oldest traces of rice in human hands are microscopic: silica bodies from rice plants, in two caves in Jiangxi, 12,000 to 9,000 years old. They are usually read as wild rice, gathered. 3232

By about 9,400 years ago people at Shangshan, in Zhejiang, were mixing rice husks into their potting clay. 3232,116 Residues in their jars have been read as rice beer.117 Whether the rice was already changing under their hands is argued. The evidence is the shape of cells from the leaf, and critics say that cannot show whether the ears still shattered.32,118

The oldest pieces of rice ear come from Huxi, nearby, and are 9,000 to 8,400 years old. Six in ten are of the wild kind that sheds its grain. Fewer than one in ten held on. 66 Rice was one food among many: the same jars held acorn, Job's tears and lily.117

A wild ear sheds its grain. People who harvest and resow favor the rare ear that holds on, and the change can be counted in the broken stalks left behind. 84,826

At Kuahuqiao, about 7,700 years ago, people burned off swamp scrub and kept a wet grassland of the kind rice likes, until the sea drowned it.38 At Tianluoshan, between 6,900 and 6,600 years ago, the share of ears that held their grain rose from 27% to 39%, and rice went from 8% to 24% of the plant remains. 3939 Acorns and water chestnuts still filled the storage pits.35

When the change was complete is argued: about 6,000 years ago by one reckoning.13 And one site spoils the neat story. At Baligang, far inland, most ears already held their grain by 6700 to 6300 BCE.40

Domestication changed rice in a handful of ways, and most are now traced to single genes. The grain stopped falling. One changed amino acid in sh4 weakened the layer of cells that lets a ripe grain drop, and in japonica a second change, in qSH1, added to it. 121,109122,3109 The plant stood up: wild rice sprawls, and a broken PROG1 gene makes it grow erect.108,123 The awns went, through at least four genes. 111,110124,125

The head changed too. It closed up, grew more branches, and came to carry about three times as many grains. 12610583,105

And the grain turned white. Wild rice is red. Nearly all white rice carries the same small deletion, 14 letters long, in a gene called Rc. 1129

The first rice fields were small and wet. At Tianluoshan, excavators describe marsh cleared with fire and spades about 7,000 years ago.42,6 The oldest field systems usually cited, at Chuodun and Caoxieshan, date to 4200–3800 BCE. Their plots were less than two meters across. 13,41120 The work at first was draining the ground, not watering it.128

The fields grew. In its late phase the field at Maoshan covered about 5.5 hectares, in squares of about 1,000 square meters. 4444,45 Twenty kilometers away stood Liangzhu, a walled city of about 300 hectares, served by earthen dams. 4646,129 Only in its time did rice become the staple.44 In the middle of the city lay a store of burned rice: 10 to 15 metric tons, by one archaeologist's estimate.130

Liangzhu ended about 4,300 years ago, in a short spell of unusually heavy rain.129

North of the Yangtze was millet country. Rice was grown on the Wei River by about 5,700 years ago, on the evidence of plant silica. Charred grain says later. Either way it stayed a minor crop there. 4747,13133,40

About 4,200 years ago the climate cooled, and by one genome study japonica then split into a temperate rice and a tropical one.12 To ripen in northern summers rice also had to lose most of its sense of day length.134

Rice farming is firmly shown in Korea from about 1300 BCE, with many paddy fields.50 It reached northern Kyushu, in Japan, around the 9th century BCE, some 500 years after Korea. 515149

Rice left the Yangtze slowly, and by one account only once the craft of the wet field had been worked out.136

By 2800–2200 BCE farmers at Nanguanli, on the west coast of Taiwan, grew rice and millet.52,53,54 Taiwan is the homeland of the Austronesian languages, and their ancestor already had three words for rice: one for the plant in the field, one for the husked grain, one for the cooked. 52222222

A husk in a potsherd at Andarayan puts rice on Luzon by about 2000 BCE, on the strength of one date.54 On the mainland, dry-field rice moved through the southern hills, and the first tamed rice in Thailand, at Khok Phanom Di, dates to 2000–1500 BCE. It was japonica. 131515,14

In the islands rice counted for less, and the sailors who went on into the Pacific left it behind for taro and tree crops. 1352,22

India had rice long before Chinese rice arrived. Charred grains at Lahuradewa, on the Ganges plain, date to about 6400 BCE. Whether they were farmed, tended or simply gathered is argued.58 Rice of clearly tamed type appears in the north only around 1800 BCE, at Mahagara. 58,1358

In between, about 2000 BCE, japonica rice came in.58,13 One model holds that it crossed with the local half-tamed rice, passed on the genes that hold the grain on the ear, and so made indica. 13,1413

The genomes half agree. Indica, japonica and a third Indian rice, aus, descend from three different wild lineages. One team finds japonica's genes in the other two, and so one true domestication. Another finds none at the genes that matter, and so three. 49794

Rice was tamed a second time, in West Africa, from a different wild grass. 1,21,5 Oryza barthii is an annual of seasonal floodwater, with awns up to 19 centimeters long and grain that falls so readily that people who gather it cut the heads unripe. 102102

One genome study finds the wild stands shrinking for more than 10,000 years as the Sahara dried, and suggests that scarcity pushed people to sow.16 In 1962 Roland Portères placed the cradle in the inland delta of the Niger, in Mali. Some geneticists agree. Others see several beginnings across West Africa. 31,5,11,16

The oldest grains come from Dia, in that delta, and date to 800–400 BCE.26,27 The plant changed as Asian rice had, by different mutations: the grain held, the stem stood up, the awns went. 31,137138,16,31125 The grain stayed red.31,61

Rice went west as a rarity. Tablets from Persepolis show it grown along the Persian royal road by about 500 BCE.62 Alexander's companions saw it in India, standing in water, and heard of it from Bactria to Syria.68,62 Theophrastus, about 300 BCE, described a grain grown mostly in water and boiled to a mash.140

Rome knew it as an import. Ships carried rice up the Red Sea, and 196 charred grains lay in an army hospital on the Rhine. 6962,636262

It stayed marginal until the early Islamic centuries.62,63 Farming manuals from Muslim Spain describe sowing and transplanting it, though only one grain has ever been dug up there. 6464 In 1475 the Duke of Milan promised twelve sacks of seed to Ferrara. 65,6665,66

By sea it went farther. Rice was the main crop of the first farming villages on the Comoros and Madagascar, in the 8th to 10th centuries. 6363

In 1012 drought struck the rice lands of the Yangtze and the Huai. The Song emperor Zhenzong had heard of a rice from Champa, in what is now central Vietnam, that ripened early and stood drought. He sent to Fujian for 30,000 bushels of seed and had it handed out with instructions. 7070

Nobody knows when the rice had reached Fujian, and historians disagree about how much the order itself changed.70 The new rice yielded less at first, and farmers selected better kinds.70 One sample tested in our own time proved to be aus, the early rice of eastern India.70

Quick rice and terraced hills eased the food supply of Song China, and drew still more people to the rice-growing south.70 A Song official, Lou Shou, painted the farming year in 21 scenes. The set was copied for centuries, and the Kangxi emperor had a new one made in 1696. 142142,143

Carolina's planters were trying rice by the 1690s. By 1770 Carolina and Georgia shipped more than 80 million pounds of it a year. 71,72144 Enslaved people grew it. Before about 1715 most were brought from the West Indies; later, from Africa. 72,7372

Since the 1970s historians have argued that they brought more than labor: that people from the rice coasts of West Africa knew the crop, and their owners learned it from them.72,74,145,146 Critics answer with shipping records. Before 1751 about a fifth of the captives landed in Carolina and Georgia came from Upper Guinea, and the Caribbean took seven times as many people from rice country and exported no rice. 7272 The reply is that the records are thinnest for the years that matter.74

The rice itself was Asian: Carolina Gold is a tropical japonica.147 African rice crossed the ocean too. Maroon farmers in Suriname still grow a little, and their oral history says it came from Africa hidden in a woman's hair. 148,7614976,74

The old rices of the tropics were tall and leafy. Fed with fertilizer, they fell over. 9577,29

In 1962, at a new institute in the Philippines, Peter Jennings crossed Peta, a tall Indonesian rice, with Dee-geo-woo-gen, a dwarf from Taiwan, or from China; the accounts differ. 77,2929,7729 A quarter of the grandchildren were short, so a single gene was at work.77,29 It proved to be a broken gene for making the growth hormone gibberellin.99,100,101

Plant 3 of row 288 became IR8, named in November 1966. In trials that year it gave more than nine metric tons a hectare, where the Philippine average was about one. 29,7729,77,7877 A Manila newspaper called it miracle rice. Its grain was chalky and it caught diseases, and hardier varieties followed. 2929,7729

China took another road. In 1970 Li Bihu found a male-sterile wild rice on Hainan, and hybrid rice was released in 1976. 80,81150,11

Rice is the staple of more people than any other food.10 In 2024 the world grew 820 million metric tons of it, in the husk, on 172 million hectares. That is nearly four times the harvest of 1961, from half as much land again. 252525 Nine-tenths is grown in Asia, and India and China grow half of it between them. 25,1025 Little of it travels: about 7% is exported.10 It comes from some 144 million farms, most of them smaller than a hectare.10

Flooded fields have costs. They give off about 8% of the methane that people cause, and rice takes up far more arsenic from wet soil than other grains do. 153,10154

In West Africa, Asian rice has largely replaced the African species, though Jola and Mende farmers still grow it for ritual.61,16 From 1992 breeders crossed the two. Their NERICA varieties were first released in 2000. In Uganda one study found they cut poverty, and another that more than half of the first growers gave them up within two years. 106,155106156157