A Mozambican woman works in a rice paddy

Cultivation of African rice spread rapidly some 2,000 years ago, and rice is now grown across the continent, from Morocco to Mozambique (pictured). Credit: John Wessels/AFP/Getty

Evolution

The story of African rice, as told by genomics

Ancient breed of domestic rice traced to the Inner Niger Delta in West Africa.

Humans domesticated rice at least twice — once in Asia and once in Africa, from different species of wild rice.

To chart the evolutionary history of African rice, François Sabot and Yves Vigouroux at the French Institute of Research for Development in Montpellier and their team analysed the genomes of 163 varieties of African rice (Oryza glaberrima) and 83 samples of its closest wild relative, Oryza barthii. Wild samples from West Africa were most closely related to domestic strains, and further modelling pinpointed Mali as the probable site of domestication.

The genome data also show that cultivation of African rice expanded around 2,000 years ago then fell sharply about 500 years ago — possibly owing to the wide import of Asian rice (Oryza sativa L.), the authors say.