Developing and testing the evolutionary reliability theory of senescence

点击翻译按钮获取中文摘要

Aging, and the bodily deterioration that comes with it, is such a universal part of human experience that it seems inevitable. Yet, why should our bodies deteriorate, and why does our risk of death increase, as we get older? Why is aging a ubiquitous phenomenon in the tree of life, from the bacteria to the most complex multicellular organisms? And, most pertinently, given that aging is detrimental to organisms' ability to survive and reproduce, why hasn't natural selection purged it from populations, so that the only causes of death are 'extrinsic' ones, such as predation and infectious disease? These questions regarding the evolution of aging have long vexed biologists, and form the backbone of this research program. Until recently, most mainstream theories of the evolution of aging centered on genes with age-specific detrimental effects. Yet, by concentrating on functioning genes with negative effects, such theories neglect what gerontologists see as the main proximate cause of aging: the accumulation of damage due to hazards like free-radicals and UV radiation. Thus, I propose to develop and test an emerging new theory that takes a damage-centric approach to the evolution of aging. My students and I will combine Reliability Theory (a branch of applied probability that deals with damage, survival, and longevity) with Evolutionary Dynamics (a formal mathematical approach to evolution) to produce mathematical and computer models to help advance an 'Evolutionary Reliability Theory of Aging'. These models will generate hypotheses which we will put to the test using broad comparisons of species that evolved under different environmental conditions, and using a suite of controlled experiments designed to examine aging in insects. This work will help us understand the enigma of aging, a question of fundamental academic importance which also has important medical and economic implications, especially in a country such as Canada that is currently in the process of a dramatic demographic shift.