The surprising statistics behind supercentenarians

Lies, damn lies and longevity.

- : Tim Harford

If there is a Dog Heaven, what must Bobi be thinking as he gazes down? Bobi's place in the record books seemed assured when he died in October at the age of 31 years and 165 days - more than two years older than his closest rival for the title of the oldest dog who ever lived.

Alas, Guinness World Records has stripped Bobi of his record on the basis that "without any conclusive evidence available to us... we simply can't retain Bobi as the record holder".

If we cannot believe that Bobi the dog was really as old as was claimed, what are we to make of the claimants to human longevity records? The oldest human ever was Madam Jeanne Calment, who died in 1997 at the age of 122, having met Vincent van Gogh when she was a teenager in Arles in 1888. (Madam Calment recalled that van Gogh was "very ugly.

Ugly like a louse".) To demonstrate such claims requires good records, which is a problem, because the key fact that needs to be verified - a date of birth only becomes interesting to most observers a century or so after the event in question. By definition, all surviving supercentenarians (110 years and up) were born before World War I.