Secret to longer life could be found in 400 -year-old shark

London: Greenland sharks, the longest living vertebrates on Earth which live for up to 400 years, could hold the secret to long life, geneticists mapping their DNA say. The sharks are believed to have unique genes which could help explain not only their incredibly long life span, but life expectancy in other vertebrates, including humans, researchers said.

Professor Kim Praebel from the Arctic University of Norway and colleagues sequenced the DNA from Greenland sharks, some of which were alive in the Georgian era. They are now searching for the unique genes which could hold the secret to the shark's longevity. The scientists have obtained the Greenland sharks DNA from tiny clippings from the fin of the shark which are caught on a line live and tagged and released.

They sequenced the full mitochondrial genome (the complete mitochondrial DNA information of an organism) of almost 100 Greenland sharks, which includes individuals born in the 1750s. The genetic sequences helped the researchers understand whether the Greenland shark has evolved specific metabolic adaptations towards extreme longevity.

They are now attempting to find the genes that hold the secret to why the sharks live so long. Researchers working with the University of Exeter in the UK believe that the Greenland sharks extreme life span makes it so unique that there is a case for giving it a special conservation status. "This is the longest living vertebrate on the planet.We are currently sequencing its whole nuclear genome which will help us discover why the Greenland shark not only lives longer than other shark species but other vertebrates," Praebel said.

When found, the long-life genes could shed light on why all vertebrates have a limited life span, and what dictates the life expectancy of different species including humans. Little is known about the biology and genetics of the Greenland shark which is found in deep water in the Atlantic ocean from Canada to Norway including the deep oceans around the North of Britain, researchers said.

The Greenland shark is widely distributed in the north Atlantic ocean. The Greenland shark is part of the sleeper shark family which has existed for around 110 million years. The oldest and largest (502 centimetres female) Greenland shark analysed by the scientists were 392 years, plus or minus 120 years: in other words they were at least 272 years old.

The study of the sharks DNA has shed new light on its behaviour, and how it is related to other members of its species living thousands of kilometres away. "Since the Greenland shark lives for hundreds of years, they also have enough time to migrate over long distances and our genetic results showed exactly that. Most of the individuals in our study were genetically similar to individuals caught 1000s of kilometres away," Praebel said.