The principles of the structure and physiology of the animal brain are described. Based on morphofunctional analysis, the main stages of the evolution of the nervous system were reconstructed. The causes, mechanisms and conditions for the appearance of nerve cells, simple nerve networks and nervous systems of invertebrates are formulated. The evolutionary theory of transitional environments is presented as a basis for the development of neurobiological models of the origin of chordates, proto-aquatic vertebrates, amphibians, reptiles, birds and mammals. The reasons for the emergence of nervous systems of various archetypes and their role in determining animal behavior strategies are outlined. Examples are given of the use of neurobiological laws to reconstruct the paths of evolution of vertebrate and invertebrate animals, as well as the basic principles of the adaptive evolution of the nervous system and behavior. The monograph is intended for zoologists, psychologists, students of biological specialties and anyone interested in the problems of the evolution of the nervous system and behavior of animals.