Behavior is the activity that results from the voluntary nervous activity of animals. Activities that are caused by purely metabolic or hormonal events are not considered behavior. Plants grow toward light. They do so because a hormone diffuses from the growing tip, primarily down the dark side of the stem, causing the cells on that side to grow more. Animals respond to low blood sugar by feeling hungry, which is a hormonal response. Animals respond to hot temperatures by increasing blood circulation to the skin, thereby allowing body heat to diffuse into the air. This is an involuntary nervous response in which the muscles around the animal's arteries relax. None of these actions are behavior. If the animal searches for food in response to hunger, or stretches its limbs to expose more surface to the air, thus allowing more heat loss, these actions would be considered behavior.

Animals raised or kept in captivity often display unusual actions that do not reflect their natural behavior. The study of animal behavior under natural conditions is called ethology.

The study of behavior can occur at many different levels. This is illustrated by the question, "Why does a bird sing?" Several different answers could be given to this question. First, a scientist could investigate the short-term causes of the singing of a particular bird. What is it about the environment, the genes, or the previous experience of this bird that makes it sing at the time, at the place, and in the manner that it does? These causes are called proximate causes, because they are near or proximate to the organism. Second, the scientist could investigate the evolutionary origin of the genes that make or allow the bird to sing. Since these causes reach far back in time, they are called ultimate causes. . .

Free term papers are not written to satisfy your specific instructions. You can use our professional writing services to buy a custom written research paper, term paper, or essay on Science at affordable price. CustomTermPapers is the best solution for those who seek help in writing term papers, essays, and research papers related to Science and other relevant topics.