Sunday, December 15, 2013

Some New Aspects Of Cellular Aging

The more theories there are to explain a set of facts, the less we understand it. There is no better example of this than the theories of cellular aging. A short list of the theories of the cause of the aging process include: the telomere length theory, the reproductive cell cycle theory, the DNA damage theory, the autoimmune theory, the free-radical theory, the cross-linkage theory, the error accumulation theory, the somatic mutation theory, the reliability theory, the wear and tear theory and so on. It resembles more the story of the blind men who feel a different part of the elephant. Researchers are describing some genetic and biochemical findings associated with aging, not the cause.

A recent study in Nature (1) makes the task even more difficult. Until now, most researches thought that aging is inevitable in most if not all species and starts occurring after the peak reproductive age. Researchers at the Max Planck Institute, however, found an extraordinary diversity in the processes of aging among the 46 species they studied, ranging from the lifespan of the fruit fly (a few days) to humans (roughly 100 years) to hydra (centuries, practically immortal). They studied 11 mammal species, 12 other vertebrates, 10 invertebrates, 12 plants and one algae. What they found was that most of our ideas on aging are false since they are based mostly on mammals and birds, which are not representative of all species on the planet. Some species become weaker with age (e.g. humans, other mammals and birds) others become stronger with age (e.g. tortoises and some trees) while other remain the same (e.g. Hydra and the hermit crab).