Life Lines by Dr. Dolittle

Sponsored by the American Physiological Society

Amazing longevity of Greenland sharks

Greenland shark

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.

Sources:

  • Dong X, Milholland B, Vijg J. Evidence for a limit to human lifespan. Nature. 538: 257–259, 2016. doi:10.1038/nature19793
  • Nielson J, Hedeholm RB, Heinemeier J, Bushnell PG, Christiansen JS, Olsen J, Ramsey CB, Brill RW, Simon M, Steffensen KF, Steffensen 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

Categories: Comparative Physiology

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