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CLEARING THE WAY. “The famous 19th century German biologist, August Weissmann, for instance, suggested – similar to Lucretius – that selection might favor the evolution of a death mechanism that ensures species survival by making space for more youthful, reproductively prolific individuals.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn

LONGEVITY GENE. “The hypopituitary Ames Dwarf Mouse was the seminal example of single-gene regulation of mammalian longevity. The mice homozygous for a hypomorphic df mutation in the Prophet of Pit1, paired-like homeodomain transcription factor (PROP paired-like homeobox 1) (Prop1) gene have deficient development of the anterior portion of the pituitary gland. Consequently, they are deficient in the production of growth hormone, thyroid stimulating hormone, and prolactin.” http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0072255 View in LinkedIn

2,000 YEAR OLD VIEW. “The Roman poet and philosopher Lucretius, for example, argued in his De Rerum Natura (On the Nature of Things) that aging and death are beneficial because they make room for the next generation, a view that persisted among biologists well into the 20th century.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn

MOUSE MODEL. “Ames dwarf (Prop1df/df) mice are remarkably long-lived and exhibit many characteristics of delayed aging and extended healthspan. Caloric restriction has similar effects on healthspan and lifespan, and causes an extension of longevity in Ames dwarf mice.” http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0072255 View in LinkedIn

THE QUESTION. “Why do we age and die? This poses an evolutionary paradox: natural selection designs organisms for optimal survival and reproductive success (Darwinian fitness), so why does evolution not prevent aging in the first place?” https://lnkd.in/ew9MzD3 View in LinkedIn

INTERDEPENDENCE. “The house sparrow, Passer domesticus is unique among wild birds in its close association with virtual dependence on man, not only in the agricultural environment, where presumably this association first evolved, but also in built-up areas. It would be expected that, with man’s dominance of the world, the future would be a bright for house sparrows, but it is now becoming an evident that this is not the case, particularly in the urban and sub-urban areas.” https://lnkd.in/e6evZ-H View in LinkedIn

FRAGMENT FROM NATURE concerns that sweetest of birds, the common house sparrow. As a boy, I was forever in barn roofs surveying their nests, stealing the odd egg, and deeply engaged by these common and perky creatures. More recently, I have built up a decent colony in my home in Catalonia, starting with just a few individuals. Their global story is heart-wrenching. View in LinkedIn

MALADAPTED BYPRODUCT. “Under Williams' hypothesis, the evolution of aging can be seen as a maladaptive byproduct of selection for survival and reproduction during youth. A fundamental corollary of Williams’ AP hypothesis is that early fitness components such as reproduction should genetically trade-off with late fitness components such as survival at old age, so that, for example, genotypes with high early fecundity should be shorter lived than those with low reproduction.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn

ANTAGONISTIC PLEIOTROPY. "George C. Williams took Medawar's ideas a step further. If it is true that selection cannot counteract deleterious effects at old age, he argued, then mutations or alleles might exist that have opposite, pleiotropic effects at different ages: genetic variants that on the one hand exhibit beneficial effects on fitness early in life, when selection is strong, but that on the other hand have deleterious effects late in life, when selection is already weak.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn

DELETERIOUS MUTATIONS. “The effects of such a mutation accumulation process would only become manifest at the organismal level after the environment changes such that individuals experience less extrinsic mortality (e.g., due to decreased predation) and thus live to an age where they actually express the symptoms of aging.” http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151 View in LinkedIn