Is laughter the best medicine? You might have thought it would be penicillin but New Zealander Geoffrey Farrow disagrees and, after all, he’s the one who’s made it to 100.

On his 100th birthday, Geoffrey told his local paper that a sense of humour ‘is always better than a packet of pills’.  A wry sense of humour stands out strongly in his interview as Geoffrey recalls that though his family was poor his father was a chauffeur ‘so I went to my christening in a Rolls Royce’. He also has a unique take on ageing, arguing that since his step-children, grandchildren and great-grandchildren all call him ‘Pop’, he’s not getting any older.

Like many of the centenarians we’ve seen, Geoffrey has had a far-from-easy life, coping with poverty and the death of his father and a brother during his childhood. So when he says that a sense of humour has been important to him, we should probably listen. But is there any scientific support for that view?

Plausibility rating: 6 out of 10. Many people do believe that laughter is good for health. The scientific study of laughter has a name – gelotology, from the Greek root gelos, to laugh (though despite being coined in 1964, the term hasn’t made it into the OED yet). There is an Association for Applied and Therapeutic Humor, which it defines as ‘any intervention that promotes health and wellness by stimulating a playful discovery, expression or appreciation of the absurdity or incongruity of life’s situations.’ If you want, you can join the Laughter Online University or train in laughter yoga through the Laughter Wellness Institute. And for a time there was even a Journal of Nursing Jocularity, from which we have a complete categorisation of 15 types of laughter, beginning with ‘smirk’, taking in ‘snicker’, ‘chortle’ and ‘guffaw’ before finishing – alarmingly for our purposes – with ‘die laughing’ (don’t worry though: the grandfather of therapeutic humour, William Fry, tells us that heat attacks during fits of laughter are so rare there is no medical literature on mirth-provoked heart attacks’).

But where’s the scientific evidence for all this? There’s little doubt that laughing does bring about physiological and psychological changes – one academic, Ronald Berk, lists 15 of them, from reduction of anxiety to increased production of endorphins.  And there’s some research suggesting health benefits. One study of US women in their 60s and 70s found that those who watched a funny video had lower levels of stress and better short-term memory. So could that lead to longer life? Possibly. A study by researchers in Maryland suggested that laughter might help prevent heart attacks.

Some promise then but – as this overview concludes – there isn’t yet enough research evidence to show that a good sense of humour directly prolongs life. All is not lost, though. Laughter may be associated with another factor that might promote longevity – a positive attitude to life – and the thoughts of Geoffrey and many others do suggest that it it least improves the quality of life.

Which is not to be smirked, snickered or chortled at.