LUTION. The habits of animals play an important part in evolution. A study of the habits or mode of life peculiar to this or that animal, i.e. wheth er it has creeping, leaping, flying, burrowing, or mining habits, is receiving at this time much at tention. The habits of an animal change with the environment. By competition a plastic form may be compelled to change its habits. A form adapted to living on land may be forced to change its habits, and become aquatic or adapted for flight. Thus the whales have evidently de scended from some terrestrial ancestor which went on all fours, and birds have apparently sprung from some four-footed reptile. The initial cause of these transformations was a change in the conditions of life, together perhaps with com petition. This led to change of habits, and this caused changes in the use or functions of this or that organ, this change being accompanied by changes in other parts of the body (correlation of parts). Hence it will be seen that the matter of habits and change of habits has direct bear ings on the evolution of organisms.
The importance of habits was clearly perceived by Lamarck, and change of habits is one of the factors of organic evolution suggested by him. He asserted that "great changes in circumstances bring about in animals great changes in their needs, and such changes in their needs neces sarily cause changes in their actions. Now, if
the new needs become constant or very perma nent, the animals then assume new habits, which are as durable as the needs which gave origin to them." Then he goes on to say that if new habits are formed "there will from this result the use of such a part by preference to that of another, and in certain cases the total lack of use of any part which has become useless." He again says: "Such is then the power of habits, which have a singular influence on the conformations of parts, and which give to the animals which have for a long time contracted certain of them fac ulties not found in other animals." Darwin also occasionally speaks of the effects of habits, both in domestic and in wild animals. At present much attention is being paid to a study of the habits of animals, since it affords data for the study of comparative psychology.
Consult: Wundt, Ethics, translated (New York, 1897) ; James, Principles of Psychology (New York, 1890), which gives ethical impli cations and pedagogical maxims; Carpenter, Mental Physiology (London, 1888) ; lluxley, Lessons in Elementary Physiology (New York, 1896) ; Sully, Outlines of Psychology (London, 1889). See ASSOCIATION OF IDEAS; CUSTOM; IN STINCT.