Significant progress has been made in the field of gerontology, which is the scientific study of old age and the aging process, even though it is relatively new. Efforts have been made by scientists to explain aging with different theories, which have been categorized into two major groups. On one hand is the group of theories which assert that aging is a natural process that our bodies have been programmed to undergo. The second group claims that aging is the effect of the damage our bodies has suffered with the passing of time. What those in the two groups will probably agree on is that genetics, physiology, chemistry and behavior come into play in the aging process. Let us examine some of the aging theories that have been put forward as possible explanations of aging.
Programmed Theories of Aging
The main argument of programmed theories of aging is that the human body has a natural aging aspect to it – aging is an integral part of human biology. The theories state that aging symptoms such as eyesight weakening, memory loss, muscle mass loss and wrinkles are programmed into our bodies. Three main systems have been connected with aging and these are the human genes, the endocrine or hormonal system and the immune system. As time passes, these systems experience changes which bring about signs of aging.
Often, comparison is made between the human body and a machine, but such is a poor comparison. A machine cannot be compared to the human body in that body parts have the ability to repair themselves, with old cells replaced and damaged tissues regenerated. An interesting fact is that our bodies comprise of 90 percent new cells every seven years. It is important to put an end to the comparison of the body to a machine to fully grasp aging. The body is an amazingly dynamic system.
One may wonder why the human body still experiences signs of aging in spite of its inbuilt ability to regenerate itself. Another force must be at work to ensure that aging is inevitable to everyone. The fact here is that aging as well as death is more about evolution than biology. The programmed theories state that both aging and death have been built into the human genes. If that were not true, there would have been no need to reproduce so as to survive. It means people will keep on living without dying as a result of aging, unless something else causes that to happen. There would be no need for evolution if people do not die biologically.
It becomes apparent that it is inevitable for aging to be programmed into human DNA. It should not merely be the effect of a medical condition or environmental factors. To programmed aging theorists, wear and tear of the body does not explain why people grow old; rather, aging is a natural process that has been programmed into our genes. Essentially, these theories hold that we are all meant to grow old and die eventually.
The endocrine or hormonal system is mainly responsible for aging in humans, according to this theory. These complex systems become less effective in their functions with the passing of time, leading to some noticeable changes. One of the possible changes is diminished HGH production, which brings up signs of aging.
There is available evidence that the programmed theory of aging may be correct. It has been observed that variation in lifespan of any species is rather negligible. For example, spider monkeys live until around 25 years, while elephants live until about 70 years. Humans are expected to live until around 80 years of age before dying. These numbers remains relatively unchanged, unless there are health and nutrition issues.
In an experiment, researchers removed the pituitary gland of some mice. The pituitary gland controls the endocrine system and regulates the production of human growth hormone (HGH). The mice were given replacement hormones to cover for the inability of their bodies to produce these naturally. These researchers were led to conclude that it is possible that the pituitary gland also secrete unknown hormones that contribute to aging after observing that the mice lacking pituitary gland outlived the control group.
It is not open to question that hormones have a role to play in the aging process. What is not clear is whether they control how fast we age or there are some other obscure factors at work within the body. Human growth hormone (HGH) is often recommended by doctors to help slow down aging. Research has shown that this prescribed HGH is effective in reversing signs of aging, but the problem is that its use comes with possibility of dangerous long-term effects.
Error Theory of Aging
Scientists working with this theory believe that aging is the outcome of damage that has been inflicted on the body by environmental factors over time. These factors cause body cells and tissues to experience wear and tear, inhibiting their ability to function as they should. This damage can be caused by different factors, including free radicals present in the body. When an organism uses up oxygen very fast, the likelihood of it dying quicker is raised.
The rate of living theory holds that living creatures, including humans, have an exact number of breaths, heartbeats and other rates. This is the oldest theory of aging. The people of old thought the human body was like a machine that is subject to depreciation.
The number of cross-linked protein molecules in the human body rises with time, hindering the functioning of these molecules. The process is usually slow and complex. But with time, these molecules can build up in body tissues such as the lung, arteries, cartilage and tendons causing a change in functions. Cross linking causes these tissues to become stiff and could lead to unpleasant conditions such as arthritis. For instance, when eye lenses become stiff, cataracts could result.
It is not possible to stop cross linking of protein molecules, but you can slow it. According to researchers, high blood sugar level raises the rate at which cross linking occurs. Major culprits for high sugar concentration in the bloodstream are foods with a high glycemic index. These foods cause sugar level to rise very fast.
Cells can be damaged and rendered ineffectual by free radicals as a result of unstable oxygen levels that they cause. The free electrons present in free radicals render molecules highly unstable, causing them to function poorly. These free radicals contribute to aging by causing protein cross linking and damage to a person’s DNA. They can be eliminated with antioxidants. It is in order to reduce the impact of or damage done by free radicals that antioxidant-rich foods are regularly recommended by medical professionals.
Aging has also been attributed to DNA damage. What we see as signs of aging could be the effects of the state of genes as time passes. Human DNA is always reproducing and there is the possibility of a cell duplicating itself improperly. Exposure to toxins, radiation and ultraviolet light can also cause cells to mutate.
The error theory of aging should not be confused with the genetic aging theory, which is concerned specifically about genes found in sperm and eggs that are transferred from one generation to another.
Evidence of Error Theory
The error theory of aging sounds valid to a degree, but it lacks sufficient evidence to back it. It has been proven that the human body cannot be correctly seen in the same light as a machine since it possesses the ability to regenerate or repair some damaged parts. To put things in the right context, it is more valid to see diminishing function, which is considered the tear half of “wear and tear,” as the effect of aging rather than its cause.
In addition, the revised version of this theory agrees that it is not possible to determine how long a person may live by merely assessing the rate of their heartbeats. Researchers have studied how fast an organism uses oxygen and concluded that species with fastest oxygen metabolism rate tend to die quickest. Slightly rapid heartbeat leads to faster oxygen metabolism and, hence, a shorter lifespan.
In a study, a group of mice where genetically engineered by researchers to have a hypothalamus defect so that they can experience over-exertion. The hypothalamus is placed near the temperature control center, causing the mice brain to overheat and lowering the core temperature. A drop in temperature of .6 degrees Celsius was observed and this helped to prolong the life of the mice by between 12 and 20 percent. Oxygen metabolism is slowed by the lower temperature which could also have effects on other systems.
The error theory focuses specifically on how long species live, but it fails to explain what factors determine the lifespan of individual species. If an individual that lives to age 90 is said to have had more heartbeats, taken more breaths or metabolized more oxygen than another that lives to 75, what could be said to have been the cause? Little to no data is available to show that a slower metabolism can help you live longer, so don’t be too eager to have that. As a matter of fact, a slower metabolism exposes you to greater risk of suffering nutrition-related conditions or becoming obese.
It has been observed in some studies on mice that increasing intake of antioxidant-rich foods can help to suppress signs of aging. As helpful as antioxidants may be in slowing aging, though, free radicals are only part of the factors that cause the problem and do not fully explain the process. However, a bit of credit must be given to the error theory of aging for showing that free radicals contribute to onset of signs of aging.
Diverse factors are obviously responsible for aging and most times you do not have any control over them. But there are some things you can do to slow the process. These include:
- Eating foods that are rich in antioxidants to help deal with problems of free radicals
- Avoiding high cholesterol foods to keep away heart issues
- Exercising regularly to check bone and muscle loss
- Maintaining mental fitness to keep your brain in the best shape
- Making lifestyle changes, including calorie restriction and positive thinking
- Using HGH supplements to stimulate natural production of HGH and other useful hormones by the pituitary gland