Tonic water and other tropical posts mixed the powder with soda and sugar, and tonic water was created. The first commercial tonic water was produced in 1858. The mixed drink gin and tonic also originated in British colonial India, when the British mixed their medicinal quinine tonic with gin. Since 2010, at least four tonic syrups have been available in the US. Consumers add carbonated water to the syrup to make tonic water, allowing drinkers to adjust the flavor intensity. Medicinal tonic water originally contained only carbonated water and a large amount of quinine. However, most tonic water today contains less quinine
Human genetic resistance to malaria only gene conferring innate resistance to falciparum malaria; there could be many such genes exerting more modest effects that are challenging to detect by GWA because of the low levels of linkage disequilibrium in African populations. However the same GWA association in two populations is powerful evidence that the single gene conferring strongest innate resistance to "falciparum" malaria is that encoding HbS. The fitnesses of different genotypes in an African region where there is intense malarial selection were estimated by Anthony Allison in 1954. In the Baamba population living in the Semliki Forest region in Western Uganda the sickle-cell heterozygote