Masoro, in the Handbook of Physiology, defines aging as deteriorative changes with time during post-maturational life that underlie an increasing vulnerability to challenges, thereby decreasing the ability of the organism to survive. This is contrary to the perception of aging as an extension of development – a viewpoint which Aubrey de Grey appropriately denounces in his assertion that aging is not an extension of development but a decay.
The inevitability of aging is often pronounced on the basis that aging is universal. Not only is this inference flawed but more importantly, the premise itself is invalid. The universality of aging is a careless conjecture as there a number of organisms which do not display increasing vulnerability to challenges with chronological age. These organisms are said to be negligibly senescent and include the jellyfish Turritopsis dohrnii, tardigrades, bacteria (at the colony level), hydra, lobsters and planarian flatworms. The strategy by which Turritopsis dohrnii achieves negligible senescence – transdifferentiation – is particular impressive. When confronted by environmental stress, physical stress, sickness and aging, the T. dohrnii adult/medusa employs transdifferentiation to revert to the youthfulness of its polyp stage. This amazing feat has gained it the title of immortal jellyfish (for in the absence of predation and disease, the process of transdifferentiation may proceed indefinitely).
Aging in humans is not merely a physiological event but is simultaneously a psychological and social phenomenon. Though not the explicit purview of biomedical gerontology, the psychological and social dimensions of aging are not beyond the concern of the life extensionist. The psychological dimension comprises the alterations that occur in sensory processes, perception, cognitive capacity, adaptability and personality. The social aspect refers to an individual’s changing roles and relationships with family, friends, and community as well as changing productive roles within organizations such as the workplace.
Biomedical gerontology is aptly fixated on the biological aspect of aging and pays little attention to its psychological and social dimensions since the eradication of aging as a biological phenomenon naturally annihilates it as a psychological and social reality. There is however a noteworthy concern that the elimination of the biological aspect of aging does not necessarily translate to an elimination of its psychological effects as the mental exhaustion and existential ennui of long life may persist even after rejuvenation. Assuming their legitimacy, such concerns may be addressed by technological developments in the science of brain aging (especially that related to microscale connectomics) as well as modulations of societal institutions to accommodate radically augmented lifespans. It is also likely that the variety of experiences afforded by future technology may effectively nullify the relevance of the “ennui” argument.