How to measure, analyze, and interpret age-related changes in Caenorhabditis elegans: Lessons for mechanistic and evolutionary theories of aging

Aging is characterized by progressive degenerative changes in tissue organization and function, some of which increase the probability of mortality. Major goals of aging research are to elucidate the series of events that cause degenerative changes, and to identify environmental, pharmacological, and genetic factors that influence these changes; this information might lead to new strategies to extend health span and lifespan. Mechanistic studies of aging depend on accurate and precise descriptions of age-related changes, since these descriptions define the aging phenotype. Here, we review studies that describe age-related changes in C. elegans, including measurements of integrated functions such as behavior and reproduction, microscopic analyses of tissue organization, and biochemical studies of macromolecules. We discuss studies that analyze the relationships between different age-related changes. We consider the results in light of mechanistic and evolutionary theories of aging. Together, these studies provide fundamental insights into aging in C. elegans that may be relevant to aging in other animals.