Aging is the natural effect of time and the environment on living organisms. These normal developmental changes include all which occur from embryonic and fetal development through senescence and death. One morbid aspect of aging is the increased vulnerability to death. The increased likelihood of death associated with aging makes it difficult to distinguish between natural aging and pathology (disease). Regardless of the difficulty, it is extraordinarily important to distinguish pathological changes from aging. For example, there is an age related increase in many types of cancer. Much of that cancer can be attributed to environmental causes and thus, while age related, is not aging. Lung cancer occurs disproportionately in mature people, however it results primarily from smoking and not aging. Alzheimer's disease, a progressive degenerative condition of the cerebral cortex, is associated with aging, however, as its name indicates, it is a pathological condition. Alzheimer's is not...