Tonic water by mass), while the daily therapeutic dose of quinine is in the range of 500–1000 mg, and 10 mg/kg every eight hours for effective malaria prevention (2100 mg daily for a 70 kg adult). Still, it is often recommended as a relief for leg cramps but medical research suggests some care is needed in monitoring doses. Because of quinine's risks, the FDA cautions consumers against using "off-label" quinine drugs to treat leg cramps. Tonic water is often used as a drink mixer for cocktails, especially gin and tonic. Vodka tonic is also popular. Tonic water with lemon or lime flavor
Human genetic resistance to malaria foothold among African populations until larger sedentary communities emerged in association with the evolution of domestic agriculture in Africa (the agricultural revolution). Several inherited variants in red blood cells have become common in parts of the world where malaria is frequent as a result of selection exerted by this parasite. This selection was historically important as the first documented example of disease as an agent of natural selection in humans. It was also the first example of genetically controlled innate immunity that operates early in the course of infections, preceding adaptive immunity which exerts effects after several days. In malaria,