Human ethology is defined as the biology of human behavior. The methods it employs and the questions it poses are elaborations of those generally used in the various fields of biology, but especially adapted to the study of man. Observation and experimentation in the natural and seminatural setting as well as the comparative method derived from morphology play important roles in human ethology, and the exploration of phylogenetic adaptations constitutes one of its focal interests. On the basis of observations on experientially deprived and nondeprived children, comparative primate and animal behavior studies, and cross-cultural investigations, certain universal phylogenetic adaptations (in terms of fixed action patterns, innate releasing mechanisms, releasers, innate motivating mechanisms, and innate learning dispositions) have been found to occur. However, human ethology does not restrict itself to the investigation of phylogenetic adaptations. The question as to how a behavior pattern contributes to survival can be posed with respect to cultural patterns as well. Similar selection pressures have shaped both culturally and phylogenetically evolved patterns. Through cross-cultural studies a number of universal social interaction strategies have been discovered.