Short answers, pulled from the story.
Raw cassava roots, peels, and leaves contain linamarin and lotaustralin, cyanogenic glycosides that the plant enzyme linamarase breaks down into hydrogen cyanide. Bitter varieties can carry up to 1,000 milligrams of cyanide per kilogram of fresh root. Eating improperly prepared cassava can cause vertigo, vomiting, ataxia, paralysis, and death.
The most effective traditional method is to peel, grate, and soak cassava in water for 48 to 72 hours, which triggers fermentation and reduces cyanogenic potential by 85 to 99 percent. The mash is then pressed and cooked as gari, fufu, or lafun, bringing cyanide levels within the WHO safe limit of 10 milligrams of hydrogen cyanide per kilogram.
Cassava was likely first domesticated in west-central Brazil no more than 10,000 years ago from the wild species Manihot esculenta subspecies flabellifolia. Portuguese traders introduced it to Africa from Brazil in the 16th century, and Spanish and Portuguese traders spread it to Goa, Malacca, eastern Indonesia, Timor, and the Philippines around the same period.
Nigeria is the largest producer of cassava, accounting for about 18 percent of world production. In 2022, global cassava root production reached 330 million tonnes. Thailand is the largest exporter of cassava starch.
Worldwide, 800 million people depend on cassava as their primary food staple. It is the third-largest source of carbohydrates in the tropics, after rice and maize, and is especially critical in sub-Saharan Africa because it grows on poor soils and tolerates low rainfall.
African cassava mosaic virus is a pathogen spread by whiteflies that causes cassava leaves to wither, limiting root growth. An outbreak in Africa in the 1920s triggered a major famine. A mutated strain that emerged in Uganda in the late 1980s destroyed leaves entirely and spread at 50 miles per year, reaching Uganda, Rwanda, Burundi, the Democratic Republic of the Congo, and the Republic of the Congo by 2005.