One of the properties of multicellular living beings is their insertion in a life cycle known by the following stages: birth, growth, reproduction, aging and death. To be ill, to age, and to die are biological determinism, results of the fragility of organic matter and the finiteness of biological life. The way this occurs has been the subject of discussions in different areas of human knowledge.

Jared Diamond, a biologist and researcher at the University of California, United States says:

"Something in our physiology makes aging inevitable. Aging can be viewed simply as an unrepaired damage or deterioration. One theory attributes aging to progressive difficulties that our immune system supposedly distinguishes between our own cells and foreign cells. Other theories relate aging to hormonal changes and neuronal degeneration [...] from the viewpoint of evolutionary biology aging is a result of the relationship between the costs of repair and reproductive advantages of staying alive. Evolution seems to have made an arrangement so that all our systems deteriorate, and we only invest in repairing them to where it is worth. "(The Third Chimpanzee).

We believe that sickness, aging and death are the result of the sum of three factors: genetic, behavioral, and reincarnatory. 

Genetic Factors  

Genetic factors have an obvious importance in an individual's longevity and life expectancy (Essential Genetics).  Jared Diamond reminds us that our ability to survive up to old age depended largely on cultural and technological advances. It is easier to defend yourself from a lion, if you carry a powerful rifle, than if you carry a spear or a stone. However, cultural and technological advances would not have been enough, if our body had not been redesigned to live longer too. No anthropoid primate caged in a zoo reaches 80 years, despite the benefits of modern human technology and veterinary attention. The mouse will be lucky if it reaches two years of age, even with enough food and veterinary attention. (The Third Chimpanzee).

Probably many genes and complex interactions of genes are related to longevity. Human aging and some diseases have been related to the progressive shortening of a region of the chromosome called telomere. Telomeres (the Greek telos, end) represent the ends of chromosomes, characterized by a high concentration of a repetitive DNA and non-coding of protein. 

Why are adult stem cells valuable  

Besides being responsible for ensuring the stability of the ends of chromosomes during the cell cycle, minimizing the chance of structural rearrangements, telomeres appears to be associated with the signaling required for proper pairing of chromosomes during cell division.

The length of the telomere is maintained by telomerases enzymes able to restore the number of present repetitions in the chromosome ends. However, most human cells have telomerase limited quantity, and each time the cell divides, a natural shortening of telomeric regions occurs until the point at which the cell loses its ability to divide and goes on to cell death. Therefore, the shortening of telomeres is directly related to aging and to various types of cancer, since it favors the occurrence of rearrangements involving the ends of chromosomes. (Essential Genetics).

According to Henne Holstege, a researcher at the Vrije University Medical Centre in Amsterdam, which conducts studies on longevity, we continue alive only while our stem cells are able to regenerate vital tissues. We die when they become "tired". Adult stem cells are present in all our organs. They are valuable for their unique ability to divide. 

Function of the adult stem cells  

While embryonic stem cells can give rise to any cell in the body, the function of the adult stem cells is to divide by means of a process called mitosis, in order to create new cells of those organs in which they were born. Blood stem cells, for example, give rise to new blood cells. Thus, they are able to replace dead cells and regenerate damaged tissue.

At one point, our stem cells reach a point of exhaustion. From then onwards, they become less and less productive to the extent that they are no longer able to regenerate vital tissues.

According to Holstege, it is estimated that people are born with something around 20,000 blood stem cells. With each cell division, the telomere length decreases, shrinking to the point of exhaustion, when the cell dies. One of the features of the cells in people who live long that has surprised researchers is the absence of harmful mutations.

Throughout life, errors caused in the process of cell division can lead to harmful mutations, which affect health, leading to the development of tumors, for example. Old aged groups, studied by Holstege's group were very little affected by this problem. The mutations found in their cells are harmless, a sign that, probably, their body has an efficient immune system, able to get rid of damaged cells before they cause harm. (Look straight, Science and Health, 4/24/2014.) 

Reincarnation factors  

The expected physical life of a reincarnated Spirit depends on factors related to his reincarnatory past. The Spirit, through his mental radiations, reflects its evolving identity, personal development needs and problems to be solved. These factors are associated with a predisposition to diseases to which the Spirit, while incarnate, may be exposed to and, obviously, to the expectancy life of the current reincarnation experience.

There are special situations in which the disembodiment surprises the individual in conditions absolutely independent of his will and behavior, i.e., disembodiment in childhood or the result of accidents or violence in which the one involved has no responsibility at all for what occurs. In these particular situations, the reincarnation factors are almost absolute.

The Spirits' Book mentions:

- Some people just escape a deadly danger to fall into another. It seems they could not escape death. Is this not destiny?

"Only the moment of death is fatal, in the true sense of the word. When this moment arrives, one way or another, you cannot escape from it." (The Spirits' Book, item 853).

- Thus, whatever the danger that threatens us, if the time of death has not yet come, we will not die?

"No. You will not die and you have several examples supporting this. When your time arrives, nothing will stop you of going. God knows beforehand what you will die of and many times your Spirit also knows it, because it was revealed to him, when he chose his existence". (LE, item 853-a). 

Influence of the Spirits in the genesis of diseases  

Emmanuel examining the determinism of death explains:

"With the exception of suicide, all cases of disembodiment are predetermined by the spiritual forces that guide the activity of man on Earth." (The Comforter, question 146).

How can the Spirit interact with genetics, setting the time of its permanence in the physical dimension? Could we then deduce that the Spirit, having in his psyche his evolutionary conditions and karmic needs, would exert a powerful influence on the genes responsible for the expression of telomerase, being directly responsible for the synthesis of  that enzyme and consequently the restoration of telomeres. He could also intervene in the number of stem cells and the dynamics of mutation. Thus, the aging process would be linked to the reincarnated personality, through obviously the natural biological processes mentioned above.

One cannot ignore, however, the influence of the disembodied Spirits in maintaining health and in the genesis of diseases in entities in the same physical dimension. Sick and troubled Spirits, in psychic symbiosis with the embodied, are able to take to them spiritual vibrations of sickly nature, contributing to the emergence of a number of physical or mental illness, which may eventually lead them to disembodiment.

On the other hand, Higher Spirits can intervene positively, contributing to the health of those they protect, acting too directly or indirectly in their bodies, anticipating or prolonging the time of death in their own benefit, or of persons related to them. (To be continued.)