The biology of Greenland Sharks have always been surrounded by mystery. Among other things their age was unknown but expected to be great.

Determining their age is particularly difficult. The extremely slow growth rates of these sharks -- less than a centimeter per year -- suggested they must live for many years. Studies conducted more than 50 years ago measured, tagged and released sharks some of which were caught again many years later and measured again. The extremely slow growth rates of these sharks -- less than a centimeter per year -- suggested they must live for many years.

Radiocarbon dating

In an attempt to estimate the age a group of scientists from the University of Copenhagen turned to radiocarbon dating. Using as a time stamp the pulse of carbon-14 produced by nuclear tests in the 1950s which left a huge amount of radiocarbon in the atmosphere which entered the diets of animals and fish, the scientists looked into its incorporation into the eye during development of Greenland sharks.

The Carbon-14 method varies somewhat in precision in different periods but taking these incertainties into account we can say with 95% certainty that the oldest shark we've measured is between 272 og 512 years old, says lead author Julius Nielsen.