Each of these papers presents provocative observations and challenges. Hayflick suggests that the predominant emphasis of research on diseases rather than the aging process itself is misguided. The Robine et al. paper explores trends in the age distribution of adult deaths, and suggests that compression of this distribution may be approaching a limit. Both papers imply a sense that mortality improvement is at least decelerating, if not limited.
In this analysis there is an attempt to inter-relate the implications of these two papers, but more important, to contrast these implications with the assumptions and projections currently being made by actuaries in the United States, Canada and the United Kingdom. These projections, in fact, suggest the prospect of a future decompression of mortality and an increasing observed maximum age at death that exceeds even the increase in the median age at death or the age to which 10 percent of births survive.
Aging, Longevity, Disease and Death
In his paper, Hayflick describes the process of aging as the gradual deterioration of molecules vital to sustaining life. Through entropy molecules lose their ability to function as required, and begin to malfunction or become inactive. Genetics, Hayflick suggests, provide the blueprint for body mechanisms to repair and maintain deteriorating molecules, and thus control our potential longevity.
Disease is a constant threat to life systems, and susceptibility increases with aging, because aging brings increased deterioration of molecular function and the ability to repair damage. The natural selection for the best genetics, Hayflick argues, operates up through the ages of reproduction where a large surplus of ability to maintain and repair body systems exists. It is after this age, roughly 40 to 50, where longevity reflects largely the surplus that has been selected for through the reproductive ages, but continually diminishes through the process of aging and the diminishing capacity to repair the effects of aging. With the diminished capacity to repair, disease has increasingly negative effects with ever increasing probability of death.