By: Maggie Diehl, Michaela Duffy, and Bryanna Norden (Stonehill College, BIO323: Evolution, Spring 2019)
When we hear the word “aging”, the first images that pop into our minds are usually those of wrinkled skin and gray hair. Although these are common visual characteristics of aging in humans (and other animals), we often fail to recognize the biological processes behind these physical features. Just as our bodies grow old and lose efficiency, our cells lose their ability to grow and divide properly. The process of the gradual deterioration of function of cells is also known as senescence, which is currently a popular topic in evolutionary biology. For many years, scientists have proposed theories to explain the inevitable struggle of aging. Likewise, they have pondered whether conditions during early development play a role in the longevity of one’s life. To examine this possibility, researchers in previous studies have used telomere length as a predictor of survival. Simply put, telomeres are noncoding DNA regions on the ends of eukaryotic chromosomes. They serve as protectors, preventing unwanted deterioration or fusion with surrounding chromosomes. Additionally, they maintain chromosome stability and serve as “mitotic clocks”, shortening (in length) with each round of cell division. When telomeres shorten to almost nothing, coding DNA is exposed and damaged, resulting in cells failing to function properly. The rate at which these vital “chromosome caps” shorten may be accelerated by various environmental stressors in early life, leading to a faster accumulation of senescent cells (which cannot replicate) and an overall shorter lifespan.
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