Oryza sativa was domesticated from the wild grass Oryza rufipogon roughly 10,000–14,000 years ago. The two main subspecies of rice – indica (prevalent in tropical regions) and japonica (prevalent in the subtropical and temperate regions of East Asia) – are not believed to have been derived from independent domestication events. Another cultivated species, O. glaberrima, was domesticated much later in West Africa.
Recent genetic evidence show that all forms of Asian rice, both indica and japonica, come from a single domestication event that occurred 8,200–13,500 years ago in the Pearl River valley region of China.
In China, extensive archeological evidence points to the middle Yangtze and upper Huai rivers as the two earliest places of O. sativa cultivation in the country. Rice and farming implements dating back at least 8,000 years have been found. Cultivation spread down these rivers over the following 2,000 years.
Puddling the soil – turning it to mud to break it down and prevent too much water percolating away – and transplanting seedlings were likely refined in China. Both operations became integral parts of rice farming and remain widely practiced to this day. With the development of puddling and transplanting, rice became truly domesticated.
Movement to western India and south to Sri Lanka was also accomplished very early. Rice was a major crop in Sri Lanka as early as 1000 B.C. The crop may well have been introduced to Greece and the neighboring areas of the Mediterranean by returning members of Alexander the Great’s expedition to India around 344-324 B.C. From a center in Greece and Sicily, rice spread gradually throughout southern Europe and to a few locations in northern Africa.
As a result of Europe’s great Age of Exploration, new lands to the west became available for exploitation. Rice cultivation was introduced to the New World by early European settlers. The Portuguese carried it to Brazil and the Spanish introduced its cultivation to several locations in Central and South America. The first record for North America dates from 1685, when the crop was produced on the coastal lowlands and islands of what is now South Carolina. It is thought that slaves from West Africa who were transported to the Carolinas in the mid-18th century introduced the complex agricultural technology needed to grow rice. Their labor then insured a flourishing rice industry. By the 20th century, rice was produced in California’s Sacramento Valley. The introduction into California corresponded almost exactly with the timing of the first successful crop in Australia’s New South Wales.
Regional development of rice cultivation
Based on archeological evidence, rice was believed to have first been domesticated in the region of the Yangtze River valley in China. Morphological studies of rice phytoliths from the Diaotonghuan archaeological site clearly show the transition from the collection of wild rice to the cultivation of domesticated rice. The large number of wild rice phytoliths at the Diaotonghuan level dating from 12,000–11,000 BP indicates that wild rice collection was part of the local means of subsistence. Changes in the morphology of Diaotonghuan phytoliths dating from 10,000–8,000 BP show that rice had by this time been domesticated. Soon afterwards the two major varieties of indica and japonica rice were being grown in Central China. In the late 3rd millennium BC, there was a rapid expansion of rice cultivation into mainland Southeast Asia and westwards across India and Nepal.
In 2003, Korean archaeologists claimed to have discovered the world’s oldest domesticated rice. Their 15,000 year old age challenges the accepted view that rice cultivation originated in China about 12,000 years ago. These findings were received by academia with strong skepticism, and the results and their publicizing has been cited as being driven by a combination of nationalist and regional interests.In 2011, a combined effort by the Stanford University, New York University, Washington University in St. Louis, and Purdue University has provided the strongest evidence yet that there is only one single origin of domesticated rice, in the Yangtze Valley of China.
The earliest remains of the grain in the Indian subcontinent have been found in the Indo-Gangetic Plain and date from 7000–6000 BC though the earliest widely accepted date for cultivated rice is placed at around 3000–2500 BC with findings in regions belonging to the Indus Valley Civilization. Perennial wild rices still grow in Assam and Nepal. It seems to have appeared around 1400 BC in southern India after its domestication in the northern plains. It then spread to all the fertile alluvial plains watered by rivers. Cultivation and cooking methods are thought to have spread to the west rapidly and by medieval times, southern Europe saw the introduction of rice as a hearty grain.
O. sativa was recovered from a grave at Susa in Iran (dated to the 1st century AD) at one end of the ancient world, another domestication of rice in South Asia.
Today, the majority of all rice produced comes from China, India, Indonesia, Pakistan, Bangladesh, Vietnam, Thailand, Myanmar, Philippines, and Japan. Asian farmers still account for 92% of the world’s total rice production.
African rice has been cultivated for 3500 years. Between 1500 and 800 BC, Oryza glaberrima propagated from its original centre, the Niger River delta, and extended to Senegal. However, it never developed far from its original region. Its cultivation even declined in favour of the Asian species, which was introduced to East Africa early in the common era and spread westward. African rice helped Africa conquer its famine of 1203.
Rest of the world
Rice was grown in some areas of southern Iraq. With the rise of Islam it moved north to Nisibin, the southern shores of the Caspian Sea and then beyond the Muslim world into the valley of Volga. In Egypt, rice is mainly grown in the Nile Delta. In Palestine, rice came to be grown in the Jordan Valley. Rice is also grown in Yemen.
The Moors brought Asiatic rice to the Iberian Peninsula in the 10th century. Records indicate it was grown in Valencia and Majorca. In Majorca, rice cultivation seems to have stopped after the Christian conquest, although historians are not certain.
Muslims also brought rice to Sicily, where it was an important crop long before it is noted in the plain of Pisa (1468) or in the Lombard plain (1475), where its cultivation was promoted by Ludovico Sforza, Duke of Milan, and demonstrated in his model farms.
Caribbean and Latin America
Rice is not native to the Americas but was introduced to Latin America and the Caribbean by European colonizers at an early date with Spanish colonizers introducing Asian rice to Mexico in the 1520s at Veracruz and the Portuguese and their African slaves introducing it at about the same time to Colonial Brazil. Recent scholarship suggests that enslaved Africans played an active role in the establishment of rice in the New World and that African rice was an important crop from an early period. Varieties of rice and bean dishes that were a staple dish along the peoples of West Africa remained a staple among their descendants subjected to slavery in the Spanish New World colonies, Brazil and elsewhere in the Americas.
The Native Americans of what is now the Eastern United States may have practiced extensive agriculture with forms of wild rice. (References to wild rice in the Americas are to the unrelated Zizania palustris.)
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