Ethology is the scientific study of animal behavior, and a branch of zoology. The desire to understand the animal world has made ethology a rapidly growing field, and since the turn of the 21st century, many prior understandings related to diverse fields such as animal communication, personal symbolic name use, animal emotions, animal culture and learning, and even sexual conduct, long thought to be well understood, have been revolutionized, as have new fields such as neuroethology.