 The study of kissing started sometime in the nineteenth century and is called philematology, which has been studied by people including Cesare Lombroso, Ernest Crawley, Charles Darwin, Edward Burnett Tylor and modern scholars such as Elaine Hatfield.Kristoffer Nyrop identified a number of types of kisses, including kisses of love, affection, peace, respect, and friendship.He notes, however, that the categories are somewhat contrived and overlapping, and some cultures have more kinds, including the French with twenty and the Germans with thirty.