Amazing longevity of Greenland sharks

Somniosus microcephalus okeanos.jpg Photo of a Greenland shark from Wikipedia.
      A multi-national team of scientists sought to determine the age of Greenland sharks (Somniosus microcephalus). These animals grow rather slowly (about 1cm per year) and are the largest fish in the arctic (>500 cm long), but their longevity was not yet known. The team used radiocarbon dating of crystalline proteins found within the nuclei of the eye lens. Because these proteins are formed prenatally, they offer a rather accurate way to estimate an animal's age. Their findings, published in Science, show that the animals reach a lifespan of at least 272 years! The largest animal tested was approximately 392 years old (give or take 120 years). They also speculate that the sharks reach sexual maturity around 156 years old.  
      A new study published in Nature reports that humans seem to have already reached our maximum lifespan of 122 years (Jeanne Calment's age at death - she was the longest-lived human on record). This improvement from 101 years in the 1860s and 108 years in the 1990s is thanks in part of genetics and modern medicine. Longevity data from France shows that more and more people are surviving into old age. The peak seems to be about age 100 after which survival begins to decline rather quickly. Their findings suggest that there may indeed be a limit to our longevity.
  • Dong X, Milholland B, Vijg J. Evidence for a limit to human lifespan. Nature. 538: 257–259, doi:10.1038/nature19793
  • Nielson J, Hedeholm RBHeinemeier JBushnell PGChristiansen JSOlsen JRamsey CBBrill RWSimon MSteffensen KFSteffensen JF. Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus). Science. 353(6300): 702-704, 2016. DDOI: 10.1126/science.aaf1703

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There may be a limit to our natural lifespan, but that doesn't mean our lifespan can't be extended. I think once we understand the cause of aging and death (and it ('and I do mean 'the' cause), we can do something about it. It appears to be a predetermined process that adjusts to environmental conditions, we can change it. No I do believe that it is impossible to stop aging, and to slow it down is a matter of engineering (perhaps, as the SENS Institute seems to think), but reversing it is the only realistic solution; and it has been done at the cellular, tissue, organic and organismic levels. Aging does not proceed at the cellular level as it does in tissue culture (a very unrealistic model of the cell as a part of the body) it proceeds on the organismic level, and the cellular level and levels in between, including the endocrine, paracrine justacrine systems and nervous system. The work in heterochronic tissue and organ transplants first showed the potential, the fact that tissue change to meet the age phenotype of their environoments, and later demonstrations that this change of age, which occurs whenever cells are induced to become pluripotent stem cells, can be accomplished by small molecules alone.
Aging is a process controlled, for example, by the superchiasmatic nucleus in the hypothalamus, which has its own cell-autonomous clock (the chemistry of which is pretty well known) system - coordination between cells of the clock decreases with age and the clock signal weakens - why? I think I know why.

By Harold Katcher (not verified) on 31 Oct 2016 #permalink