Nikolaas Tinbergen, a Dutch zoologist, with the Austrian biologist Konrad Lorenz founded the field of modern ethology---the study of animals in their natural surroundings. The two men shared the Nobel Prize for physiology and medicine with Karl von Frisch (see Vol. 5) in 1973. Convinced of the sterility of much contemporary comparative and experimental psychology, and appalled at the far-reaching generalizations made by psychologists on the basis of observations of a few species of caged rodents, Tinbergen set out to study a few highly specific problems in animal behavior: the nature of the stickleback's courtship, the stimuli causing a young herring gull to beg for food, and the reasons gulls bother to remove empty eggshells from their nests. His influential book The Study of Instinct (1951) had a tremendous impact on the development of ethology. Ethologists believe that instinct is a motivational basis for human behavior as well as for animal behavior and hence that ethological studies have valid human applications. Tinbergen is particularly concerned that human beings are in danger of losing their ability to adapt because of the very rapid changes taking place in contemporary society. He thinks there is much we can learn from close study of animal adaptation.