Life Extensionists - Average and Maximum Lifespans

Average and Maximum Lifespans

During the process of aging, an organism accumulates damage to macromolecules, its cells, its tissues and its organs. This accumulated damage is the result of oxidation damage to the cell contents caused by free radicals, though other things cause aging as well.

The longest a human has ever been proven to live is 122 years, the case of Jeanne Calment who was born in 1875 and died in 1997, whereas the maximum lifespan of a mouse, commonly used as a model in research on aging, is about four years. Genetic differences between humans and mice that may account for these different aging rates include efficiency of DNA repair, types and quantities of antioxidant enzymes, and different rates of free radical production. The most important and challenging factor remains the telomere limitation of each individual species.

Average lifespan in a population is lowered by infant and child mortality, which are frequently linked to infectious diseases or nutrition problems. Later in life, vulnerability to accidents and age-related chronic disease such as cancer or cardiovascular disease play an increasing role in mortality. Extension of expected lifespan can often be achieved by access to improved medical care, vaccinations, good diet, exercise and avoidance of hazards such as smoking.

Maximum lifespan is determined by the rate of aging for a species inherent in its genes and by environmental factors. One widely recognized method of extending maximum lifespan in organisms such as nematodes is calorie restriction. Another technique used evolutionary pressure such as breeding from only older members.

Theoretically, extension of maximum lifespan could be achieved by reducing the rate of aging damage, by periodic replacement of damaged tissues, or by molecular repair or rejuvenation of deteriorated cells and tissues and the enhancement of telomerase enzyme activity. Future research will be geared towards telomere repair strategies.

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