“Senescence” is a term used in many different scientific fields, including biology, gerontology, botany, and cytology. In all cases, it relates to the changes associated with aging. Some biologists study a natural phenomenon called negligible senescence, in which certain species of wild animals have been found to experience few or none of the effects of aging most animals endure. Tortoises, for example, are believed to be capable of living indefinitely as long as they receive proper nutrition, care, and protection from disease or infection.