Category: Uncategorized

THE THEORY. "Lotka’s intrinsic rate of natural increase, with respect to an increment to age-specific mortality at an age a. Thus, he obtained a linear approximation for loss in fitness due to any deleterious mutations that raised mortality at an age a. The greater the loss in fitness, the faster should mutant alleles be selected out of a population, and the fewer should be found at equilibrium as recurring mutations balance natural selection." https://lnkd.in/eyTNv3H View in LinkedIn

NUANCED EXCEPTIONS. "The results here show that there is an unexpected and far-reaching difference between effects restricted to late stages and effects only concentrated at late stages, carrying with them some small crucial share of early-age effects." http://www.pnas.org/content/110/25/10141.full View in LinkedIn

IN PLAIN WORDS. "Mutation accumulation theory: From the evolutionary perspective, aging is an inevitable result of the declining force of natural selection with age." http://longevity-science.org/Evolution.htm View in LinkedIn

THE FORMAL THEORY. "The ‘mutation accumulation’ theory, first proposed by Medawar...refers to the fact that deleterious alleles with effects restricted to late stages of life equilibrate at higher frequencies at mutation–selection balance than alleles that act earlier […].” https://lnkd.in/eDZKgvJ View in LinkedIn

SO ENDS this first of two weekends on reductive evolution. This report suggests that reductive evolution is not only far from being rare, rather it is a common form of evolution, characterized by explosive bursts of genomic complexity followed by slow winnowing of the chaff. This it at odds with the popular view of evolution as an inexorable ascent to complex (human) perfection. The Copernican Revolution has been slow to take hold, it seems. View in LinkedIn

BAD GENE ACCUMULATION. "However, if the rate at which these mutations are generated is higher than the rate at which natural selection can weed them out, then the collective genomes of the organisms in the species will suffer a meltdown as the total number of deleterious alleles increases with each generation." http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1004351 View in LinkedIn

NEW PERSPECTIVE. "The scale of death’s recent evolution is also difficult to grasp, and accepting it may require a thorough reorientation toward life." https://muse.jhu.edu/chapter/275814 View in LinkedIn

TWO GENE BUFFER. "It has long been appreciated that there is a limit to the number of deleterious mutations that an organism can sustain per generation. The presence of these mutations is usually not harmful, because diploid organisms generally require only one functional copy of any given gene." http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1004351 View in LinkedIn

SHIMMERING BACKDROP. "Like life, death is a facet of underlying continuity, endlessly moving and evolving." https://muse.jhu.edu/chapter/275814 View in LinkedIn

GENETIC DRIFT. "We are promoting the idea that the power of random genetic drift imposes a lower bound to the degree to which natural selection can reduce the mutation rate. This drift-barrier hypothesis seems to support a number of previously disconnected observations, including the increase in the mutation rate with reductions in effective population size, the magnified error rates associated with DNA polymerases and repair enzymes used only infrequently in replication, and the extraordinarily high rates of base misincorporation into transcripts." https://biodesign.asu.edu/mechanisms-evolution/research View in LinkedIn