Age-old question: What are the factors behind a long life?

Why do some individuals die much sooner than others, despite belonging to the same gene pool and facing similar life challenges? What lifestyle factors, if any, influence life-expectancy?

The Greenland shark found by teenagers Hammad Chaudhry and James Winter O’Donnell  on the seashore at Finisklin, Co Sligo. Picture: Irish Whale and Dolphin Group via Facebook

And all the days of Methuselah were nine hundred sixty and nine years: and he died — Genesis 5

In mid-April, teenagers Hammad Chaudhry and James Winter O’Donnell came upon the carcase of a large fish on the seashore at Finisklin, County Sligo. The cadaver proved to be that of a Greenland shark, a species never recorded previously in Irish waters. This species of shark, the world’s longest-lived vertebrate, can live for four hundred years and reach a length of six metres. The Finisklin specimen, three metres long, was about 150 years old when it died. A comparative youngster in shark terms, it had scarcely reached puberty.