Scientists have used a unique method to determine that Greenland sharks (Somniosus microcephalus) are the world's longest-lived vertebrates.
It involves identifying a 'pulse' of carbon-14 in the animal's eye lens known to be caused by atmospheric testing of nuclear bombs in the mid-1950s. (This same spike in 14C was detected in samples of wood from the alleged 'Noah's Ark' site on Ararat associated with a Hong Kong-based team. It established beyond reasonable doubt that the wood was from a tree growing in that same decade—see www.creation.com/hong-kong-ark-fiasco.)
The technique helped researchers to establish that the shark has a very slow annual growth rate of about 1cm which translates to a lifespan of around 400 years.
Other known long-living creatures include the chowder clam (500 years), bowhead whale (200) and Galapagos tortoise (170).
Bible skeptics scoff at the idea that humans such as Methuselah (969 years, Genesis 5:27) once lived for centuries and say that would be 'biologically impossible'.
Ignoring death by accident or disease, different living things seem to be genetically programmed to live for different average periods. Such 'programmed longevity' in animals can be drastically affected by breeding experiments.
For humans, it may be that the population bottleneck after Noah's Flood (only eight people survived) contributed to the dramatic decline in post-Flood lifespans.
There is also considerable evidence that the relentless accumulation of many mutations each human generation also played a part, as renowned geneticist Dr. John Sanford explains in his book Genetic Entropy.?
Pennisi, E., Greenland shark may live 400 years, smashing longevity record, sciencemag.org, August 2016.
Nielsen, J., et al., Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus), Science 353(6300):702–704, August 2016 | doi: 10.1126/science.aaf1703.