Biological immortality refers to a stable or decreasing rate of mortality from cellular senescence as a function of chronological age. Various unicellular and multicellular species may achieve this state either throughout their existence or after living long enough. A biologically immortal living thing can still die from means other than senescence, such as through injury or disease.
This definition of immortality has been challenged in the new Handbook of the Biology of Aging, because the increase in rate of mortality as a function of chronological age may be negligible at extremely old ages, an idea referred to as the late-life mortality plateau. The rate of mortality may cease to increase in old age, but in most cases that rate is typically very high. As a hypothetical example, there is only a 50% chance of a human surviving another year at age 110 or greater.
Read more about Biological Immortality: Cell Lines, Organisms, Political Struggle For Immortalism and Immortality, Life Extensionists
Famous quotes containing the words biological and/or immortality:
“Although there is no universal agreement as to a definition of life, its biological manifestations are generally considered to be organization, metabolism, growth, irritability, adaptation, and reproduction.”
—The Columbia Encyclopedia, Fifth Edition, the first sentence of the article on “life” (based on wording in the First Edition, 1935)
“The immortality of the soul is a matter which is of so great consequence to us and which touches us so profoundly that we must have lost all feeling to be indifferent about it.”
—Blaise Pascal (1623–1662)