Chocolate is a popular food derived from the seeds of the cacao (cocoa) tree theobroma cacao, originating in Central and South America. It has been enjoyed by humans throughout the world since its first cultivation more than 3000 years ago, but is actually poisonous to many other species because of its theobromine content, which the human digestive system can efficiently break down. For example, dog owners are advised not to feed chocolate to their pets, but instead enjoy for themselves any of the thousands of varieties of commercial or home-made chocolate available globally today. These are divided into several types, with the distinction between milk, white and dark chocolate most easily recognised.
The history of chocolate - from xococatl 'bitter water',[1] in the Central American Nahuatl languages - goes back to a spicy, bitter ceremonial drink produced by the Maya and Aztec peoples. After the destruction of the Aztec Empire by the Conquistadors in the sixteenth century, cocoa was exported to Europe by the Spanish Empire. It became popular with the wealthy, and in the nineteenth century milk chocolate was created. In the twentieth century, chocolate became more affordable, and so was eaten by more and more people.