It used to be thought that aging is the ticking away of some internal clock to a predetermined plan laid down in your genes. Dr. Leonard Hayflick, a noted research scientist, grew human cells in tissue cultures and showed that they could subdivide to create new cells only a limited number of times.
This fibroblast replicative limit, as it was termed, appeared to show that the human cell has an inbuilt timer that eventually runs down. The evidence looked good and the study was repeated in several laboratories, but numerous scientists could not accept the aging “clock” theory.
One problem with tissue culture experiments is that the life of the cells is dependent upon the adequacy of their nutrition. If there is even the slightest deficiency in the nutrient, medium used to grow the cells or in the air, water or temperature, or any one of a hundred variables, then the cells will accumulate damage. Every successive cell division is then progressively impaired until the cells no longer replicate and dies. These cell deaths have nothing to do with an internal clock, but are caused by environmental damage.
Chronological age is not biological age. How do we know this? There are two main lines of evidence.
First, though average levels of many physical functions show a progressive decline with age, there is a wide variability within aged groups. Some individuals show no decline at all. That these individuals exist indicates that chronological aging is not an inevitable cause of biological aging.
Often a person will blame a health condition, such as a bad shoulder, a bad knee, etc on their age. But if age were to blame, then it would stand to reason that both shoulders and both knees would be degenerated and not just one limb. These problems are due to cumulative stress and traumas, not to the passage of time.
The second line of evidence that aging is in fact degeneration caused by abnormal stress is the continuing discoveries that aging process previously considered natural do not occur at all in some human populations. Blood pressure for example, rises with age in the American population, and used to be considered an inevitable part of aging. Science knows now, however, that there are numerous populations, mostly isolated from Western society, in which the elderly have the same blood pressure as the young. Science has known that rising blood pressure is caused by complex factors in the environment of Western society.
When members of populations migrate to Western society, their blood pressure begins to rise with a few years.
Osteoporosis is a major health concern for western women; however, women in other cultures around the world do not suffer from osteoporosis and similar degenerative disorders.