ethology, study of animal behavior based on the systematic
observation, recording, and analysis of how animals function,
with special attention to physiological, ecological, and
evolutionary aspects. Laboratory or field experiments designed
to test a proposed explanation must be rigorous, repeatable, and
show the role of natural selection. At one time, an organism's
actions were classified as either instinctive or learned
behavior; the former included those actions, such as common
reflexes, that are not influenced by the animal's previous
experience; the latter comprised those actions, such as problem
solving, that are dependent on earlier experiences. Current
thinking emphasizes the complex interaction of environment and
genetically determined responses, especially during early
development. Among the early ethologists were Herbert Spencer,
Charles Darwin, G. J. Romanes, and William James. Zoologists
Konrad Lorenz and Nikolaas Tinbergen are widely considered to be
the founders of modern ethology. In 1973 they