Aging

"We as for long life, but 'tis deep life, or noble moments that signify. Let the measure of time be spiritual, not mechanical."

- Ralph Waldo Emerson

http://www.time.com/time/specials/packages/article/0,28804,1963392_1963365_1963378,00.html

It is difficult to pinpoint a direct cause for aging, as many studies have shown that various factors contribute to an organism's lifespan. Therefore, it is safe to say that aging is caused by both genetic and environmental factors. We are not able to control the genes we inherit, but our lifestyle choices can help us amplify beneficial genes and negate the effects of undesirable ones. For instance, if someone has a family history of heart attacks and high cholesterol, choosing to lead a healthy lifestyle can help him or her overcome these predispositions and live to a much higher age than previous generations.

One genetic trait tied to aging is telomere length. Telomeres are stretches of DNA at the end of chromosomes that help protect genes from being harmed by general use. However, as cells divide, telomeres get shorter and shorter. There is a gene that controls the default telomere length, so naturally, having longer telomeres signifies longer lifespan (Moisse, 2010). The shortening of these telomeres correlates directly with age-related diseases, such as heart disease, cancer, diabetes and Alzheimer's, which is why it may seem hopeless for someone with a low expression of the telomere size gene to want to be healthy. However, there are benefits to not smoking, eating unhealthy foods and being inactive: these things all accelerate the rate at which our telomeres are shortened, so in that regard, making good lifestyle choices can help a person overcome genetic deficiencies (Park, 2010).

Shortened telomeres are an example of a gene expression related to early death, but there are also genes that signify longevity. This family of genes known as sirtuins enable a physiological response to stress within a cell, promoting DNA repair and preventing cell death. The power of these genes was highly underestimated until biologist David Sinclair fed one group of yeast cells a normal amount of glucose, and gave the other group a restricted amount (Chaddha, 2007). He found that the yeast cells with the restricted diet lived up to 50% longer because SIR2, yeast's primary sirtuin, activated an emergency response that slowed the formation of waste DNA. Without this waste interfering with the cell's processes, the group with the lower-calorie diet actually seemed to age slower, and thus allowing them to divide more over the course of their lives (Chaddha, 2007). Later research revealed that SIRT1 is the primary sirtuin in mammals, so scientists are now looking at what lifestyle choices we can make to encourage the expression of SIRT1 to promote longevity.

http://www.cakens.com/research/understanding-the-mechanisms-of-ageing-worth-a-nobel-prize/

As shown by Sinclair's experiment, calorie restriction, while unproven, seems like a probable method to increasing lifespan. However, it is an impractical solution, because humans typically like to eat. Luckily, a substance known as resveratrol (commonly found in red wine) has been shown to induce the effects of calorie restriction without the need of going on a strict diet. Some studies have shown that drinking red wine increases lifespan, but the degree to which it helps is currently unknown. In one study, mice who were given resveratrol lived 10-20% longer, but to simulate the same effect in a human, it is predicted that we would have to drink 1000 glasses of red wine a day (Cohen, 2007). Again, not very practical.

http://www.pfiwestern.com/magazine/index.php/2008/09/26/red-wines/

The interplay between genetics and lifestyle is evidence once again when we examine HDL (high density lipoproteins). Blood samples taken from people who have lived past the average life expectancy of 78 years in the United States have shown that the amounts and sizes of HDL within these people are typically larger (Cohen, 2007). HDL, commonly referred to as the "good" cholesterol, cleans out the blood vessels by removing LDL (low density lipoproteins, the "bad" cholesterol) that clog vessels and may lead to atherosclerosis and heart attack. While HDL/LDL levels certainly have a genetic component to them, eating foods low in saturated fat may be incredibly beneficial, as it reduces LDL in the body and leaves blood vessels clean and open. Because of this, it is important to remember just how much control we have over our health. While our family histories may lead us to believe that we are predisposed to certain diseases, scientists are discovering more and more just how important lifestyle is to extending our lifespans as much as possible.

Lastly, I'll emphasize this: it is not the quantity of years that determines a person's value, but rather the quality of those years. There is no point to a long life if you can't enjoy that life. I wish you the best life possible.

http://www.pfiwestern.com/magazine/index.php/2008/09/26/red-wines/

Chaddha, Rima. (2007, January 1). Healthy Old Age. Retrieved November 10, 2010 from http://www.pbs.org/wgbh/nova/body/aging-longevity.html. 

Cohen, Chad (Producer). (2007). Aging [Videoclip]. Boston, MA: PBS Video.

Moisse, Katie. (2010, February 8). Researchers Identify Genetic Variant Linked to Faster Biological Aging [Electronic version]. Scientific American. Retrieved November 10, 2010.

Park, Alice. (2010, February 11). How to Love 100 Years [Electronic version]. Time.  Retrieved November 10, 2010.