What is responsible for aging?

What we need to survive is exactly what helps us progress towards our senescence? That is the question that kept running through my head as I read the reading for this week. Oxygen and glucose are essential for sustaining human life, but more specifically they are needed for proper brain function. A few minutes without oxygen, or a very low level of blood glucose, causes the brain to shut down (which in turn leads to death). Biologically, the ideas of rusting and browning discussed in the chapter make quite a bit of sense.

Science has brought us to the point of understanding some processes that can be thrown in to swim amongst the countless other things that are thought to contribute to aging. Throughout the chapter, the authors insisted that looking at only one scientific process provided only one view on aging and that viewing one aspect leaves other things being overlooked. The ideas that humans are prone to rusting like the Tin Man and browning like a steak on the grill provide simple analogies regarding aging. While the Tin Man and steak represent two different processes, there are countless other processes that can be associated with countless other analogies regarding aging.

In class, we discussed the point of how one views aging with the knowledge their background and expertise has provided them. The most striking example what how an Evolutionary Biologist would define aging, depending on what parameters had been set by the inquiring party. At this point in time, with the varying view points, hundreds of theories and countless analogies we have encountered, I have thought of a visual representation of these varying viewpoints.

Depending on one's background, looking into the globe at the concept of aging will give a different picture. Like the infinite number of ways to look into a globe, there will always be infinite ways to look at aging because we see what we believe. After all, as the author says "with our focus on longevity and survival so far, it is easy to forget that some aspects of aging have little to do with staying alive" (pg. 144).

Why do we age?

The chapter "Why does aging happen?" disproved two theories behind aging. The theories disproved included the good-of the species theory and limited cell division theory. At first, each of these theories seemed to make some logical sense but after further reading, the explanations given by the authors also provided a logical argument against the validity of such theories. All of the ideas and research brought up in the reading caused me to start pondering exactly what the cause of our aging could be.

I do agree that the limited cell division theory can be associated with aging without being a causal theory. While reading about the cell division theory, I thought about the large number of other scientific discoveries that have been made in the field of cancer research over the last decade. Mutations in the Ras family (genes involved in cell signaling) have been found in approximately 90% of patients with pancreatic cancer (http://www.cancerquest.org/ras-oncogene). This subject was not touched upon in the reading but it certainly adds significance to the limited cell division theory.

Life expectancy has increased throughout the last century due to discoveries in the field of modern medicine (e.g. vaccines that have almost completely eradicated certain diseases). With increased technology, fewer persons die at a young age due to infection or simple illnesses such as the common cold. This medical revolution has led to a new phenomenon which was not known of 50 to 100 years ago. Following reproduction, there are often illnesses and conditions that set in that can expedite the aging process. While Cancer is not the cause of aging, it (and other illnesses) seem to be the one cause behind senescence for those who have aged. In my mind, this gives an answer to the question of why do we ultimately die but it does not exactly answer why we age prior to senescence. At this point, I believed that aging and senescence could be connected somehow.

While looking around online, I stumbled upon the evolutionary senescence theory of aging (http://www.afar.org/pdfs/AFAR-Guide-to-Theories-of-Aging.pdf - page 3). Natural selection was touched upon in the reading with disproving the good-of-the-species theory of aging, and it plays a role in the senescence theory. The key to natural selection is reproduction. Following reproduction, natural selection does not necessarily prevent the aging that every person experiences because the goal of natural selection has already been met. I feel that the evolutionary senescence theory can especially be applied to women because following menopause (the natural loss of reproductive capabilities) there are many other health issues such as osteoporosis, cancer and arthritis that set in. The onset of these medical conditions often age a sign of aging because mobility or physical ability is lost within ones body.

There is no final answer on whether the evolutionary senescence theory of aging is right or wrong, however, it has yet to be disproved. The theory ties in cellular life to the life of an organism while explaining the one phenomena science has yet to prevent, senescence.

In time, there will be an answer to the question "Why do we age?", but until that time, it is anyone's best guess as to why we really age.

Healthy Aging

Age: A word we encounter on a frequent basis.

What is age?

Age could be a number, a state of mind, or something much more complex. I believe that aging is the change that occurs to an organism over a period of time.  When one measures age, there are an infinite number of ways that one can look at it. It is not simply the dilemma of whether the glass is half full or half empty. Aging can be viewed a change physical, mental, spiritual or emotional state.  

What about healthy aging?

I believe that healthy aging intertwines many factors of human life. We all inherit genetic material that causes us to be predisposed to certain effects of aging. Occurrences such as hair loss at a young age cannot be entirely avoided with any sort of lifestyle due to predispositions. The loss of hair certainly does not mean that one is experiencing unhealthy aging.

The lifestyle choices that we make often have the greatest impact on defining ‘healthy aging’. Healthy lifestyle choices that lead to healthy aging include eating well (fruits and vegetables), being active and taking adequate care of yourself. Routinely visiting the doctor for physical examinations and actively partaking in preventative medicine.  

Another essential part of healthy aging is keeping a positive outlook on life. Having a negative outlook about life or not keeping good company will prevent one from having a healthy aging experience.

The main activities that I consider to contribute to unhealthy aging are anything in excess (excess eating, inactivity, alcohol use, etc) and leading an unhappy life. If you are more satisfied with life, you are more likely to find the good in a bad situation and not put yourself under too much stress regarding the situation.

Overall, I feel that healthy aging involves leading a life you love and enjoy. While we are all human, and aging is inevitable, we can all choose whether our aging is healthy or unhealthy by the little choices in life.