Cognition is a form of adaptation to the environment. It has been invented by organisms with well-developed neural systems. Consequently, like other adaptive characteristics, cognition is, on one hand, supposedly continuous among species; on the other, it is diverse and depends upon the two constraints-phylogenetic constraints, which restrain the body structure of the organism, and ecological constraints, which correlate with the lifestyle of the organism. This book highlights the diverse aspects of cognition among a wide variety of organisms. Seventeen leading researchers in the field from seven countries illustrate the diverse aspects of cognition among various organisms ranging from insects to humans of different ages and pathological states. This volume will inspire scientists and students who strive to understand cognition and, in particular, those who aim at doing so from genetic and adaptive perspectives.