Immortality? genetics and living forever

By Brian Edgar

Although medical technology is constantly finding new ways of dealing with various health disorder, maintain general levels of health and delaying death the typical maximum age span has not really changed in a long time. Everyone dies of something, and although good health in old age has significantly improved,  a cure for one disorder simply means that people die of something else. However, it is likely that in the not-too-distant future that we will be presented with the prospect of medical technology which will enable human life to be radically extended by hundreds of years!

This paper focuses on the nature of this technology and the theological implications for the understanding of immortality in the context of this possible development in the third millennium. It was first published as  ‘A New Immortality? Reflections on Genetics, Human Aging and the Possibility of Unlimited Lifespan’  in Evangelical Review of Theology: Journal of the World Evangelical Fellowship  Vol. 23 No 4, (1999) 363-382.

It was subsequently awarded a John M Templeton Award for Writing on Science-Religion and was republished in Robert L Herrmann (ed), Expanding Humanity’s Vision of God: new thoughts on science and religion (Philadelphia: Templeton Press, 2001)

The full paper is available:  A New Immortality?
  and the introduction is reproduced below.

A New Immortality

One of the theological challenges of the twentieth century has been to respond to those issues relating to the creation of human life. Whether theology has adequately met the challenge or not birth control and enhancement techniques must rank as one of the major social developments of the century. The  contraceptive pill and abortion have had an enormous impact on social structures, family relations, female and male roles, sexual attitudes, work patterns and global economics. Birth enhancement techniques including the various reproductive technologies, in vitro fertilisation, genetic engineering, cloning, genetic screening and gene therapy are set to have a similar impact. All of these developments require a theological understanding of the nature of the person and of the way in which humanity reflects the image of God both individually and socially and it is likely that the twenty first century will not see any easing of the imperative to describe the nature of the human person in theological terms. In fact, it is more likely that an even more intense scrutiny of theoanthropology[i] (the theology of the human person) will be needed due to developments concerning the extension and then the ending of human life. This will come about because of the probability that we are soon to be presented with the prospect of medical technology, known as telomere therapy, which will enable human life to be extended by hundreds of years and perhaps indefinitely.  This paper will focus on the theological implications for the understanding of immortality in the context of this possible development in the third millennium.

Telomere Therapy[ii]

It is a serious possibility that telomere therapy will be available for extending life span between 2005 and 2015.[iii] The technology involved goes beyond attempting to establish optimum standards of good health in order to achieve greater longevity, and well beyond attempts to eliminate individual diseases. Telomere therapy is aimed at investigating and manipulating the most fundamental aging mechanisms of the human body so that there can be an almost unlimited extension of human life.  One of the simplest ways for anyone to gauge the social significance of such a discovery is to ask happily married people what they think it would be like to be married ‘till death us do part’ if both partners are going to live four hundred years. There are enough significant implications for career and work patterns, global population,  marriage and family structures and social relationships to guarantee a large-scale social transformation.

The various component organs of the body have different cells which function in a variety of ways according to the needs of the particular organ and they reproduce themselves at different rates. The life of the whole organism is longer than that of any of the individual cells of the body but the life span of the organism as a whole is  restricted if the various organs are not able to reproduce cells. Until the early 1960’s it was generally assumed that cells could, theoretically, perpetually reproduce themselves and that the failure of cells to do so was simply the result of an accumulation of degenerating conditions. In 1961 Leonard Hayflick and Paul Moorhead demonstrated the falsity of this and showed that even under optimal conditions cells would only reproduce a finite number of times.[iv] Each cell type has its own reproductive limit, now known as the Hayflick limit. Some cells however, do not seem to have this limitation. The very problem with cancer cells is that they reproduce indefinitely, to the point where the sheer number of cells overwhelms the normal functioning of the host.  If the processes which control this can be discovered and manipulated might it not be possible to find a way to cause cancer cells to reach a reproductive limit and also to persuade normal bodily cells to reproduce indefinitely and thus extend the lifespan of the organism as a whole?

Telomeres are structures found at the ends of eukaryotic linear chromosomes and consist of thousands of tandem repeats of the DNA sequence TTAGGG. These terminal repeats are highly conserved among all vertebrates. Every time a cell divides the chromosome is duplicated and its telomeres get shorter. In 1986 Howard Cooke of the Medical Research Council in Edinburgh noticed that telomeres in reproductive cells were longer than those in shorter lived somatic cells such as those found in skin and muscle. Most normal  somatic cells have Hayflick limits which are comparable but some cells, including the reproductive cells, need to divide more than would normally be the case. Cooke speculated that the somatic cells might not be able to make an enzyme to repair their telomeres and that this would account for them reaching their Hayflick limit after less replications than reproductive cells. And it seems that he is right -  it is likely that the telomeres are the molecular clock that triggers replicative senescence. Once a threshold number of TTAGGG repeats is reached cells become unable to divide. Some cells, however, produce an enzyme called telomerase which rebuilds and maintains the telomeres and thus extends their replicative life. Telomerase has now been found in a number of classes of normal cells (including,  stem cells, gonadal germ cells,  skin fibroblast cells)  and all of them are cells with a high turnover rate or which are in a continuously replicating pool of differentiating cells. It seems that an extended replicative life is made possible by the presence of telomerese. It is also significant that the level of telomerase in these cells is still significantly less than that found in cancer cells which are virtually ‘immortal’.[v]

In 1998 several studies were conducted in which human cells were cloned. Some were telomerase negative and they exhibited telomere shortening and normal cell senescence. In one study those cells which were telomerase positive exhibited both elongated telomeres and delayed senescence, exceeding their normal life span by at least 20 doublings, thus indicating that perhaps telomere loss is the intrinsic timing mechanism in human cells. To be able to treat human cells with telomerase in this way is thus a significant step forward not only in the search for significantly extended life span but also, more immediately, in the treatment of certain aging problems including atrophy of the skin, muscular degeneration, atherosclerosis.[vi] Down’s syndrome and failed bone marrow transplants could also benefit from telomerase treatment[vii] and it may be an answer for those with Hutchinson-Gilford syndrome[viii] who have an average life-span of 12.7 years (and, significantly, skin fibroblasts with telomere lengths characteristic of cells from far older patients.[ix])

The role of the telomeres in this is only one part of a broader theory. Human aging is controlled by gene expression and operates though free radical damage to the cell. Senescent cells have altered function (through gene expression changes such as altered patterns of collagen production) and increased damage (as a result of poorer control of free radical metabolism). Such senescent cells introduce dysfunction at the cell and organ levels of operation. Altogether, the process is a complex picture of senescent gene expression regulated by telomeres and the telomeres are only one part of the picture. They are, though, the part of the process which has had the focus. Fossel says that ‘shortly after the year 2000 telomere therapy will be available for treating cancer and telomere therapy will be available for extending your life span between 2005 and 2015.’[x]

This is not to say that even the greatest success with telomere therapy would eliminate death. Even if this scenario turns out to be right people will still be able to wear out and die and no one will be immune from other diseases and accidents. Perhaps talking in terms of an indefinite lifespan is more accurate as it leaves open the question of the ultimate human life expectancy.

Even though in relatively recent times there have been significant changes to mortality rates it seems that over the past forty thousand years at least there has not been any significant change in potential life span. The fact that no Neanderthal skeletal remains have been discovered which give any indication of a life span of more than thirty or forty years simply indicates that this was the maximum possible given the very significant environmental dangers that were faced. Even two to three thousand years ago, environmental conditions meant that the average life expectancy was low, but evidence from ancient Egyptian, Hebrew, Greek and other cultures point to a reasonably consistent picture in which the maximum human life span in optimum  conditions is  70 to 100 years. [xi]

Nor is the general constancy of the maximum human life span negated by great changes to mortality rates in the twentieth century. In this century in western society there has been an increase in average life span of around 25 years. For example, in Australia in the 1990’s the average life expectancy was around 80.5 years for females and around 74.5 years for males instead of about 48 and 51 years respectively at the turn of the century. But this average increase is obviously is achieved by keeping people alive longer, especially by reducing infant mortality, rather than by extending the maximum possible life span which has not significantly changed. To illustrate this one may ask how much longer a person can expect to live, assuming a person avoids disease and accident and survives to 65. In the USA in 1900 it was a further 11.5 years (male) or 12.2 years (female). Today it is only three to five years more than that. In short, medical science has had significant success in increasing the average life expectancy but so far has only managed a modest improvement in the normal maximum lifespan…………………..

[i] Theoanthropology is simply a conflation of ‘theological anthropology’. It is a convenient way of referring to the theological understanding of humanity which avoids the non-inclusiveness of ‘doctrine of man’ and the absence of convenient nouns and adjectives relating to the ‘doctrine of humanity’. It is, of course, possible to use ‘anthropology’ and ‘anthropological’ but these refer to the study of humanity in the widest possible sense and when used without qualification are usually taken to refer to what is more properly called ‘cultural anthropology’.

[ii] Acknowledgment is made of the assistance of Edmund Sim of the University of Queensland who read the paper and made valuable suggestions regarding some of the scientific details.

[iii] M.Fossel, Reversing Human Aging, (New York: William Morrow and Co., 1996), p. 222

[iv] L. Hayflick and P.S. Moorhead, Experimental Cell Research, 25, pp. 585-621.

[v] W. Wright, M. Piatszek, M. Rainey, W. Byrd, J. Shay, Developmental Genetics 18, pp. 173-179

[vi] A.Bodnar et al, ‘Extension of Life-span by Introduction of Telomerase into Normal Human Cells’, Science, January 16, 1998,  pp. 349ff.

[vii] L. DeFrancesco, ‘Looking into longevity with telomere detection kits’, The Scientist, Vol.12:7, March 30, 1998.

[viii] Juvenile progeria – an aging disorder.

[ix] M. Fossel, Senescent Gene expression, telomeres and aging, telomere.htm

[x] Fossel, Reversing Human Aging, p.222

[xi] In Ancient Egypt it was not considered completely inappropriate to aspire to live 110 years and the reign of 67 years of Ramses II points to a death at around 90 years of age. Plato and Sophocles were considered old when they died at about 80 and 90 and of course there is the biblical ‘three score years and ten’. (Bromley, The Psychology of Human Aging, 37: S. Austad, Why we age: what science is discovering about the body’s journey through life, (New York: John Wiley, 1997) 37.) Nor does the evidence of Genesis 5 run counter to this general picture. Prior to the eighteenth century the long lives attributed to Adam, Seth, Methuselah and others were generally accepted as real descriptions of life span. However, the combined effect of biblical criticism and biological evolution led to them being more generally reckoned to be artificially exaggerated lifespans. It is important to note that large figures such as these are not only a Hebraic phenomenon but are consistent with certain Sumerian king lists of about 2000 BC. R.K. Harrison sees the apparent lifespans of Genesis as the result of some combination of an enhanced reckoning by the family and a mathematical manipulation by an archivist with the intention of honouring significant people – in accord with a broader ancient near eastern tradition which also influenced the form of the Sumerian king list material. (R.K.Harrison, ‘From Adam to Noah: a reconsideration of the antediluvian patriarchs’ ages’, in Journal of the Evangelical Theological Society 37:2, (June 1994), pp. 161-168.) Other interpreters find somewhat different versions of this answer but whatever the nature of the precise solution it would seem that these figures are best taken as cultural phenomenon rather than as biological data.

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