Caloric Restriction and
Behind our quest for a clearer understanding of the aging process in animals doubtless lies the hope that we may somehow be able to use this information to extend our own maximum possible lifespan. For some single-cell species, maximum lifespan is to some extent a plastic quantity: It may not be defined at all in terms of calendar time, as our own lives are, but rather as a fixed number of cell divisions. In times of depleted resources, single-cell organisms can even go into a death-like state to prolong life, where they may stay for years, further complicating a precise definition of maximum lifespan. For some invertebrate species, even when maximum lifespan is defined in years or months, it can often be manipulated by relatively simple means such as changing growth temperatures. For warm-blooded mammals such as ourselves, maximum lifespan, at least in the wild, seems to be a genetically regulated property of each species, even though it may only be observable in highly artificial environments such as zoos or laboratories. Still, the fact that in organisms like round-worms
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Publication information: Book title: A Means to an End: The Biological Basis of Aging and Death. Contributors: William R. Clark - Author. Publisher: Oxford University Press. Place of publication: New York. Publication year: 2002. Page number: 131.
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