The evolution of ageing is a field flush with misconceptions, misunderstandings, and hiatuses. In this thesis I address the most important misunderstanding and misconceptions, and develop new... Show moreThe evolution of ageing is a field flush with misconceptions, misunderstandings, and hiatuses. In this thesis I address the most important misunderstanding and misconceptions, and develop new theory to fill the gaps. This work directly leads to the restatement of the central question in the evolutionary theory of ageing. Rather than evaluating evolutionary forces in models that are at best weakly rooted in (patho-) physiological mechanisms, usually phrased in terms of __age-specific genes__ that are not further specified, as is the current practice, the most pressing question becomes why an organism cannot, or does not, do in itself what it is perfectly capable of doing outside itself in the form of reproduction, namely producing a perfectly healthy __young__ organism. Evolutionary forces cannot answer this question. If anything, this is a mechanistic question. I suggest investigating __the evolution of unretainability__: why and how has our form of life evolved, in which it is mechanistically impossible to bring ageing to a halt, and what are the responsible mechanistic constraints? Show less
Wensink, M.J.; Heemst, D. van; Rozing, M.P.; Westendorp, R.G.J. 2011
One of the prevailing theories of aging, the disposable soma theory, views aging as the result of the accumulation of damage through imperfect maintenance. Aging, then, is explained from an... Show moreOne of the prevailing theories of aging, the disposable soma theory, views aging as the result of the accumulation of damage through imperfect maintenance. Aging, then, is explained from an evolutionary perspective by asserting that this lack of maintenance exists because the required resources are better invested in reproduction. However, the amount of maintenance necessary to prevent aging, 'maintenance requirement' has so far been largely neglected and has certainly not been considered from an evolutionary perspective. To our knowledge we are the first to do so, and arrive at the conclusion that all maintenance requirement needs an evolutionary explanation. Increases in maintenance requirement can only be selected for if these are linked with either higher fecundity or better capabilities to cope with environmental challenges to the integrity of the organism. Several observations are suggestive of the latter kind of trade-off, the existence of which leads to the inevitable conclusion that the level of maintenance requirement is in principle unbound. Even the allocation of all available resources to maintenance could be unable to stop aging in some organisms. This has major implications for our understanding of the aging process on both the evolutionary and the mechanistic level. It means that the expected effect of measures to reallocate resources to maintenance from reproduction may be small in some species. We need to have an idea of how much maintenance is necessary in the first place. Our explorations of how natural selection is expected to act on the maintenance requirement provides the first step in understanding this. Show less
