BIOLOGY IS NOT DESTINY
After much research it became evident that there is a biologically controlled aging process, and it is designed to get all of us in the end. If there were not such a thing as biologically controlled aging, then people who live on pure organic food, or reside on serene mountain tops, or chant mantras with the sunrise would be immortal. With there low stress, high level of physical movement, and a good diet, they would not die of anything. But of course that is not the case, as we all age because aging is biologically based. There is an abundance of evidence of this. The cells of the body age just as the body does. When you put cells into a test tube and grow them, they divide only a finite period of time before they stop dividing. This know as a "Hayflick Limit", named for the scientist, Leonard Hayflick who discovered it. Once the cell stops dividing it ages and dies. The ability of the cells to reproduce is closely related to life span. Species like humans have cells with a far greater division potential than those of short lived critters like mice. Aging is also related to divisional potential. Old people's cells in culture putter out much faster than those of younger people, while cells from a fetus multiply like bunnies on a rampage until they too eventually run out of steam.
There is evidence that each cell has a clock or counter that is governed by a piece of DNA known as the telomere at the end of each chromosome in the nucleus of each cell. After each cell division, the telomere becomes a tiny bit shorted. When a critical amount of the telomere has been removed, the cell can no longer divide. Its metabolism slows down, it ages and dies. New research shows that the counter can be turned ON and turned OFF in the cell. The control button appears to be an enzyme called telomerase which can lengthen the telomere and allow and allow the cell to divide endlessly. Most cells of the body contain telomerase, but it is in the OFF position so that the cell is mortal and eventually dies. But other cells are immortal because the telomerase is switched ON. For example the hemopoietic cells, the progenitors of blood cells are immortal, but unfortunately so are cancer cells. Cancer cells do not age according to the telomere theory, because they produce telomerase, which keeps the telomere intact. In the not too distant future we will have telomere therapies that control the counter (clock) in each cell, blocking telomerase in cancer cells so that they stop dividing and die off and relengthening the telomere in aging cells so that they become young again.
There are other signs of aging in the cell. The proteins become gummed up in a process known as cross-linking. One form of cross-linking occurs when sugar molecules become attached to proteins and DNA, a process known as glucosolation, which can results in the aptly named accumulated glycosolation endproducts (AGE). Cross-linked proteins can cause cataracts in the lens of the eye, clog blood vessels, and jam the filtering mechanism in the kidneys. Free radicals generated by the break down of oxygen in the body damages cells, particularly the power houses of the cell known as mitochondria. The genetic material of the cell, the DNA itself, becomes torn apart and damaged with time and even though it is repaired, the repair processes cant keep up with the rate of damage.
But there is one way in which aging is exactly like a disease. Until very recently in human history, disease was thought of as a natural process. There was nothing you could do about it. Tuberculosis, smallpox, dysentery, the plague were just part of the natural order of things, God's will. All you could do was go to church and pray that it didn't happen to you. It wasn't until doctors understood that diseases were caused by something, like viruses, bacteria, the environment, that it became possible to prevent or cure them. Now we are at the same point in regard to aging. Aging which has long been thought of as inevitable, part of the human condition, can now be seen as a disease for which there are causes and treatments.
Fortunately we humans do not accept the natural order very easily. If we did we would still be living in caves and hunting with spears and stones. But we are an animal that changes it's environment, and by changing it's environment, we change nature. We have rewritten the rules of disease, and with growth hormone replacement, we are re-writing the rules of biology and aging.