Turkish Journal of
GERIATRICS

Professor of Biobehavioral Health The Pennsylvania State University, USA Some of the many hypotheses of aging advanced over the past 50 years are discussed and evaluated. Assessment of the experimental evidence suggests that , under particular environmental and genetic conditions any one of these may provide an accurate description of mechanisms by which aging occurs. Keywords : Aging; Caloric Restriction; Cell Survival; Cytokines/metabolism; Immunity; Longevity; Models, Biological; Models, Chemical; Reactive Oxygen Species