The study of the evolution of emotions dates back to the 19th century and has come to be known as "sensusology". Evolution and natural selection has been applied to the study of human communication, mainly by Charles Darwin in his 1872 work, The Expression of the Emotions in Man and Animals. Darwin researched the expression of emotions in an effort to support his theory of evolution. He proposed that much like other traits found in animals, emotions also evolved and were adapted over time. His work looked at not only facial expressions in animals and specifically humans, but attempted to point out parallels between behaviors in humans and other animals. According to modern evolutionary theory, different emotions evolved at different times. Primal emotions, such as fear, are associated with ancient parts of the brain and presumably evolved among our premammal ancestors. Filial emotions, such as a human mother's love for her offspring, seem to have evolved among early mammals. Social emotions, such as guilt and pride, evolved among social primates. Sometimes, a more recently evolved part of the brain moderates an older part of the brain, such as when the cortex moderates the amygdala's fear response. Evolutionary psychologists consider human emotions to be best adapted to the life our ancestors led in nomadic foraging bands. This book is designed to be a general overview of the topic and provide you with the structured knowledge to familiarize yourself with the topic at the most affordable price possible. The level of discussion is that of Wikipedia. The accuracy and knowledge is of an international viewpoint as the edited articles represent the inputs of many knowledgeable individuals and some of the most currently available general knowledge on the topic, based on the date of publication.