Month: September 2022

THE BALANCE. “The evolution of lifespan can be viewed as a balance between selection for increased reproductive success and the factors that increase the intrinsic age-dependent components of mortality.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn

DEFENSES. “Species that are well protected from predators – for example, those that have a shell, can fly, or are poisonous – tend to live longer than related, less well-protected species.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn

SOMA VERSUS GERM LINE. “For a long time it was thought that bacteria do not age. Indeed, one of Williams' strongest assertions about the evolution of aging was that only organisms with a separation of germ line and soma should age. In such organisms, the germ line is maintained indefinitely, but the aging soma is “disposable” after fulfilling its reproductive role. Bacteria, by contrast, do not exhibit a clear delineation into germ line and soma, and should therefore be immortal.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn

SYMMETRY. “More important than this lack of a clear germ line/soma distinction, however, is the fact that prokaryotes, protozoans, algae, and symmetrically dividing unicells, do not have clearly delineated age classes. In symmetrically dividing unicells, for example, individuals should not age because parent and offspring are phenotypically indistinguishable – it is impossible to determine old from young, and age is thus invisible to selection. By the same logic, aging should exist in asymmetrically reproducing organisms where aging parents are phenotypically distinct from offspring.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn

SYMMETRY EXCEPTION. “An asymmetrically dividing bacterium has recently been found to show senescence. Remarkably, however, even the symmetrically dividing E. coli ages: it shows subcellular mother-offspring asymmetry, delineating age classes upon which selection can act to produce senescence.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn

INEVITABLE PROPERTY. “Even when cells divide symmetrically, unicellulars readily evolve a state of asymmetric, unequal distribution of cellular damage among daughter cells. However, as soon as such an asymmetry evolves, aging evolves. Thus, aging – despite remarkable variation in the duration of life among different species – might be a fundamental and inevitable property of cellular life.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn

THE REMNANT. “After reproductive maturity in animals that age, the level of remaining physiological reserve determines longevity. The reserve does not renew at the same rate that it incurs losses because mole- cular disorder increases at a rate greater than does capacity for repair. This increase in molecular disorder is aging which increases vulnerability to predation, accidents or disease.” https://lnkd.in/esfPTAR View in LinkedIn

CELLULAR ENTROPY. “Hundreds of biological changes occur in normal cells as they replicate in vitro resulting in increasing molecular disorder and loss of cell function.” https://lnkd.in/esfPTAR View in LinkedIn

YOUTH YIELDS TO AGE. “The number of population doublings that a cell strain is capable of undergoing and that is determined by telomere length, may be the in vitro expression of maximum potential longevity. The hundreds of molecular disorders that herald the approaching loss of replicative capacity, and diminution of telomere length, are age changes.” https://lnkd.in/esfPTAR View in LinkedIn

ENTROPY AND PATHOLOGY. “When molecular disorder occurs in dividing cells in vivo, post mitotics may also be affected and both may then reveal increasing vulnerability to pathology and subsequent death of the individual well before species maximum longevity is reached.” https://lnkd.in/esfPTAR View in LinkedIn