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Essay on Theories on the Causes of Genetic Disorders in the Elderly

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Genetic Conditions Leading to Mortality are Common in Older People than Younger People Humans undergo several stages during their lifetime including growth, development, reproduction and senescence. Senescence is defined as the deteriorative biological changes that organisms experience as they age eventually leading to death. These changes include low metabolism, a weak immune system, memory loss, poor vision and loss of hearing. Senescence begins in humans during their post-reproductive years. However, gerontology research has shown that individuals who reproduce late have longer life spans compared to individuals who reproduce early. Nonetheless, it does not indicate that senescence is inevitable. All organisms experience senescence,…show more content…
Another example includes the repression of tumorigenesis that inhibits certain cell growth at a young age but rapidly expresses harmful cells resulting in inoperable tumors at an older age. This suggests a trade-off between the early benefits and the late costs. Natural selection will always favor the early benefits in young adults over the late-acting deleterious genes. Charles Williams proposed that individuals who postpone reproduction have longer lifespans because they have a higher fitness and can produce more children (Williams 409). The mutation accumulation theory was proposed by Peter Medawar in 1952. It stated that harmful mutations expressed at a younger age are selected against by natural selection to maximize the fitness of an individual. Deleterious mutations expressed at an older age are not affected by natural selection because the genes are already passed onto the next generation (Hughes 424). Over the next generations, the late-acting deleterious genes accumulate resulting in degradation of biological processes. The mutation accumulation theory and the antagonist pleiotropy theory are similar to a certain extent and can occur at the same time. However, an important difference is that harmful genes at old age accumulate from previous generations in the mutation accumulation theory while
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