Read this: The broad field of animal communication encompasses most of the issues in ethology. Animal communication can be defined as any behavior of one animal that affects the current or future behavior of another animal. The study of animal communication, called zoo semiotics (distinguishable from anthroposemiotics, the study of human communication) has played an important part in the development of ethology, sociobiology, and the study of animal cognition. Animal communication, and indeed the understanding of the animal world in general, is a rapidly growing field, and even in the 21st century so far, a great share of prior understanding related to diverse fields such as personal symbolic name use, animal emotions, animal culture and learning, and even sexual conduct, long thought to be well understood, has been revolutionized. A special field of animal communication has been investigated in more detail such as vibrational communication.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): What are some fields of knowledge concerning the animal world that have been revolutionizes in the 21st century?
animal emotions, animal culture and learning