Chocolate lowland climate in the narrow band of latitudes where cacao is grown (20 degrees north and south of the equator), the commercial company Mars, Incorporated and the University of California, Berkeley are conducting genomic research in 2017–18 to improve the survivability of cacao plants in hot climates. Chocolate is made from cocoa beans, the dried and fermented seeds of the cacao tree ("Theobroma cacao"), a small, 4–8 m tall (15–26 ft tall) evergreen tree native to the deep tropical region of the Americas. Recent genetic studies suggest the most common genotype of the plant originated in the Amazon basin and
Black drink theorized to be black drink rituals, including what some anthropologists have interpreted as vomit issuing from the mouths of mythological beings. Pottery samples recovered from sites in modern Southwestern United States and Northwestern Mexico have tested positive for the ratio of methylxanthines associated with those produced by "Ilex vomitoria". The same study also identified methylxanthines ratios associated with "Theobroma cacao". Neither plants are native to the areas from which the pottery samples were recovered, which suggests trading between areas where those plants are native. The chemical analysis also suggests a possible increase in drinks prepared from cacao after the year