Bartholomew A. Ochia
Throughout the ages, mankind has been obsessed with the desire to achieve extreme old age. In ancient and mediaeval times futile efforts were made to discover the “elixir “of life. To this day mankind still entertains the desire to extend human life to extreme old age. Today there are obvious increases in human life expectancy, thanks to the advancement in medical science for the control of diseases, increases in food production, provision of clean water and improvements in environmental hygiene. The prospects of extending human life span are discussed in relation to the role of genetic and non-genetic factors. The conclusion is that deliberate modifications of the genetic make-up of complex organisms, including mankind, is now possible for correcting genetic defects or altering heritable characteristics, paving the way towards extending human life indefinitely.
Over the years there have been many reports of unidentified flying objects (UFO’s). These reports have been treated sceptically by most people. However, there is an increasing number of individuals, even governments, who think that there might be something in these reports that warrants further investigation. Whatever your position is regarding UFO’s, there is little doubt that out there, somewhere in the universe, there are civilisations millions of years more advanced than we, who may have solved the mystery of immortality and agelessness and are able to organise inter-galactic and inter-stellar voyages taking myriads of years. This belief is based on the principles of probability, since there are over one hundred million stars in our galaxy and over one hundred million galaxies in the universe. Will mankind ever evolve to such a degree of perpetual agelessness? This is the intriguing question which this article will try to address.
From the dawn of civilization, mankind has been obsessed with the desire to attain extreme old age. In ancient and mediaeval times, futile efforts were made by the use of alchemy, to discover the “elixir vitae”. The first emperor of China is said to have ordered his scouts to seek out some wise men who might know how to make that elixir. This type of search continued even after a period of 2000 years. Ponce de Lion thoroughly searched the wilderness of what is now known as the southern states of America, in the hope of finding the ‘Fountain of Youth’. Even at this present age the search continues for some Shangri-La where individuals may live up to, or over, 150 years. In spite of these futile efforts, mankind still entertains the desire to extend human life to extreme old age. And there are already signs that it is progressing in the right direction. In most countries of the world life expectancy has been increasing since the turn of the 20th century. These gains have been made possible because of the many advances in medical science for the control of diseases, use of antibiotics, increases in quality and quantity of food, provision of clean water and advances in environmental hygiene.
A particular question which one is inclined to pose at this juncture is this: What are the prospects of extending human life span? To try to answer this question, it is essential to examine the two broad factors which are believed to influence the ageing process.
The first is genetic. Most gerontologists believe that the genetic apparatus of the living cell is the major arena where the primary events associated with ageing occur. It is well known that each cell type undergoes a definite number of divisions during its lifetime. Researchers have shown that for most tissues this number is between fifty and fifty-five. After that the cell type is no longer able to divide or repair itself. The age at which a cell attains this stage is determined by several factors, among them genetic coding.
That ageing is at least determined by genetic factors is supported by the following observations. 1) Certain organisms have life spans specific to them. For instance, the golden hamster lives for just 2 to 3 years, whereas the crown pigeon survives up to 16 years, the loggerhead turtle to 33, the eagle owl to 68, man to 115 and marions tortoise to 152. 2) Hybrid vigour, resulting from crossing two strains, influences life span. Experimental results indicated that the first generation from crossing two strains of the fruit fly Drosophila melanogaster lived longer than did their parents, and that by crossing two geographically isolated strains of the fruit fly the differences in life span between offspring and parents were even more pronounced. 3) It is a common knowledge that women, who carry the Y chromosome, on the whole live 7.6 years longer than their men folk, who carry the X chromosome. 4) It is well known that persons whose parents lived to 75 years or over tend to live longer that those whose parents died at 60 years or less. Fathers of long-lived sons are known to have lived longer than those of short-lived sons, that is, under normal circumstances. It is thus safe to assume that genetic factors play some crucial role in the events that result in ageing and eventual death of individual members of any species.
The second set of factors that influence ageing are the so-called non-genetic. These may include loss of cell function due to the accumulation of waste substances in the cell; mechanical and chemical fatigue in tissues and organs; and inactivation and changes in growing and dividing cells. Furthermore, antibodies whose primary function it is to protect the body by attacking and destroying foreign bodies, commence to attack and destroy normal body cells. Molecules of collagen, which is the stable and supportive protein of the skin, tendon, bone, cartilage and other connective tissues, may be immobilised by structural changes induced by free radicals. These free radicals are highly unstable oxygen atoms that bond indiscriminately with many vital molecules in the body, rendering them ineffective. Also, fats contained in cell membranes may combine with oxygen atoms in the process called per-oxidation, and end up destroying the cell. These non-genetic factors may indirectly be modified by genetic traits.
If it is agreed that genetic mechanisms primarily determine the ageing process, then what are they? Geneticists have already defined four main ways of answering this question, according to Hayflick. The first is what they call the instability of the genome: when a genetic damage occurs, an un-programmed ageing may result. The second is the gradual accumulation of non-genetic damage which slightly affects the survival of the individual before it attains reproductive maturity. The third involves the presence of genes that bring about ageing; these genes can slow down vital body processes. It is believed that during evolution these genes are selected because they help the survival of the species as a whole in preference to that of the individual. The last mechanism is programmed ageing. In this the degenerative processes of ageing are brought about accidentally as a passive by-product of the genetic selection of favourable characteristics. A full understanding of these mechanisms will enable man to intervene, interfere or even modify them to his advantage in his quest for increased life span.
The social and ethical implications of human life prolongation have been the subject of debate for a very long time; and it is a debate which always evokes strong passions from all those involved. Their differences aside, there is one common belief among them; and that is: the objective of all the scientists involved in human biological research should be to decrease the rate of human ageing, so as to defer the onset of disabilities and diseases which are related to ageing and, as such, bring about benefits to the individual, in particular, and society, in general.
And now, the mind-burgling question: How can mankind tamper with genetic factors in order to prolong human longevity?
The following discussion might aid to answer the question.
From ancient Rome to modern industrialised societies, there has been a progressive shift in the percentage survival time of populations towards a later age. What have brought about this shift are improvements in living conditions, medical facilities, nutrition and sanitation. However, the age of the longest survivors has, in fact, remained about the same, around 100 to 115 years, from time immemorial. In modern times the graph obtained by plotting percentage survival against age is almost attaining a horizontal shape. This means that even if we could eliminate all the major known diseases of ageing, such as vascular disorders, maturity-onset diabetes and cancer, the average human life span might only be extended by about 6 years or so. It appears, therefore, that the principal killer of persons of very advanced ages is not actually disease itself, but accidents associated with increasing feebleness of very old age.
Life expectancy from the age of 60 years has surprisingly improved only slightly since 1789, according to scientific data. But what has indeed changed is the larger number of people surviving to the apparent limit of 100 to 115 years. In many developed and affluent societies people can expect to survive to a ripe old age.
For a moment, consider a world in which all causes of death, be they accidental or disease-linked, were eliminated. The probable outcome on human life span will be to realise the ultimate rectangular curve, as mentioned above, in which all citizens will live their lives, without fear of untimely death, but fully convinced that by midnight on their 100th or so birthday, they would drop stone dead. This scenario appears utopian, but it is already occurring and it will continue to evolve because nearly all efforts in biomedical research are being geared heavily towards combating ageing-related diseases. Little attention is devoted to the study of the factors which influence biological ageing itself. These factors act in a clock-like fashion. Perhaps, more research efforts devoted towards studying them will enable mankind to appreciate the potential extent of its life span.
What then are the prospects for understanding these clock-like operating factors and increasing human longevity?
Experiments with laboratory animals have indicated that reduction in daily energy intake during early infancy can increase longevity by up to 50%. Reduction in dietary energy intake delays the onset of maturity and, so, retards ageing. So far human subjects have hardly been used in this sort of experiments. Of course the reason is not far to seek. For most persons quality of life is much more important than quantity of life. However, people would not tolerate a treatment that will increase their rate of ageing and, at the same time, double their pleasure. That being so, then eventually there will be the need for energy-restriction experiments on humans aimed at decelerating the ageing process.
Mild, long-term lowering of body core temperature has been used to reduce the rate of ageing. Experiments on populations of the annual fish, genus Cynolebia, kept at 15oC lived much longer than did those maintained at 20oC. The snag, however, is that lowering body temperature tends to depress humoral and cellular immunity, which in effect should accelerate ageing. In spite of this, life span is considerably increased by lowering core body temperature.
Certain chemical compounds, known technically as 2-mercaptoethanol, polynucleotides and thymic hormones, may be used to partly reinvigorate lapsed immune potential of old animals. The possible effects of these chemicals on life span and disease pattern could be unravelled in further studies by scientists.
Groups of scientists in the United States and elsewhere have recently been developing the technique of culturing primordial tissue cells using human embryos. The purpose of this is to use each specific cell type to repair ageing or diseased body tissues, thus making it possible to cure the incurables. Very recently Harvard scientists have developed a technique of revering the ageing process in mice.
Some scientists believe that curtailment of sleep can be used to increase active life expectancy. Sleep takes up to a third of most people’s lives. Therefore, any method that can reduce the time spent sleeping should increase the time allotted to productive occupations and enjoyment of life. Evidence shows that a moderate one-hour daily reduction of sleep could increase our ‘life span’ by about 2 years; this, according to Hayflick, could be equivalent to a world totally devoid of deaths from cancer.
Manipulation of the immune system can be used for extending life span. The immune system of an old animal may be partly or totally reconstituted by injecting or grafting young immunocompetent cells.
Another major method which can be used to control ageing process is the modification of the biological clock itself by means of genetic manipulation or genetic engineering. There exist already techniques for achieving this. Among them is the so-called ‘recombinant DNA experiment’ that involves the construction, in the laboratory of organisms with unique properties that are not known to develop naturally. These organisms can then be used to impart those properties onto others. Genetic engineering, a topic very much in the news nowadays, involves the insertion of foreign genes into bacteria, virus or cells of higher organisms growing in tissue culture.
At this juncture, the reader may be aware that deliberate modifications of the genetic make-up of complex organisms, including mankind, is now possible for correcting genetic defects or altering heritable characteristics. Now, how can human societies face the complex and difficult social, economic and political issues that the use of these techniques might provoke? That is the crucial question.
The ultimate result from research on the biology of ageing might be the total elimination of all ageing-related physiological debilities. However, by combining research on the biology of ageing and that aimed at controlling the biological clock, mankind, many believe, will be on its way towards immortality. This notion of biological immortality is as fascinating as it is intriguing and, even infuriating to the deeply religious. As pointed out above, mankind has already acquired the elaborate means for fighting the plagues of ageing and, theoretically speaking, the basic technology for re-setting the biological clock and prolonging life span. With time the technology will be perfected and fine-tuned.
The notion of mankind’s immortality may be considered now by many as the stuff of science fiction. However, for serious thinkers this notion is hovering at the brink of science fact. The social consequences of a moderate increase in life expectancy are enormous. It has been suggested that a mere increase of 5 years in the life expectancy at, for instance 75 years, will be enough to completely overwhelm present-day medical welfare facilities and medical institutions, not to mention the tremendously increased requirements it would pose in the care for the aged. These are problems we perceive in this day and age, given the present level of mankind’s development and knowledge. It should be noted that throughout life a normal person uses only a small fraction of his/her brain potential. With time, cosmic time measured in tens of thousands and millions of years, mankind will be able to evolve systems to solve all those problems. It will be able to better control the weather, irrigate whole deserts to increase food production and evolve new and incredibly effective socio-economic, national and international systems.
In the meantime, one goal which all mankind seems to readily accept is the reduction of the physiological incapacities which accompany ageing. Attainment of this goal will usher in the era when men and women will live productive, vigorous, mentally alert, independent and high-quality lives until their biological clocks cease to function on their 80th to 115th birthday when they quietly die. To all mankind this is the ultimate achievement. Quality, and not quantity, of life is what matters. After all, of what use is immortality if it is not accompanied by full enjoyment of life?
For those who believe in UFO’s, the infinite extension of both quantity and quality of life as well as the infinite expansion in mental capability will prepare mankind for embarking on inter-stellar or even inter-galactic voyages to discover and ultimately inhabit other planets, especially so when our own sun starts to die away in the next five billion years. To those who would be involved in those voyages, “Bon Voyage”.