Many of you will have seen a series of uplifting pictures of an orangutan, published in the Mail.

Showing the animal’s reaction to a simple sleight-of-hand conjuring trick, the images took the animal from puzzlement through understanding to what seemed a glorious fit of joyous laughter.

If you thought only humans could see a joke, it was time for an immediate re-think. The orangutan had been shown a ‘now you see it; now you don’t’ trick by a handler, who first showed the animal a chestnut in a cup and then secretly removed the nut before showing the cup again.

Are you watching carefully? The man places an unripened chestnut inside a polystyrene cup

Not impressed? The man shows the ape that the chestnut has vanished and at first it does not react

When the orangutan cottoned on that he’d been ‘had’, he responded with what we humans can’t help but understand as hilarity, rolling on the floor in apparent mirth. The orangutan was laughing at the wacky incongruity of seeing a chestnut in a cup and then finding it gone.

Just like that! As Tommy Cooper would have said.

It all begs the question: do animals really have a sense of humour? Or rather — because humans are animals — do non-human animals have a sense of humour? Or is humour actually a barrier that divides us from our closest animal relatives and from every other species?

This sounds like the cue for a million stories about how your dog enjoys a laugh — almost every owner has his or her own anecdotes of canine pranks that suggest a real (if primitive) sense of humour.

Konrad Lorenz, an Austrian zoologist who won the Nobel Prize in 1973, believed dogs laughed when they played.

‘The slightly opened jaws which reveal the tongue, and the tilted angle of the mouth which stretches almost from ear to ear, give an impression of laughing,’ he said.

‘This “laughing” is most often seen in dogs playing with an adored master and which become so excited they soon start panting.’

But is the panting ‘laughter’ Konrad witnessed simply a factor of canine physiology? Dogs may look as if they’re laughing when they’re doing nothing of the sort. So what about other species?

There is a YouTube video of a dolphin in a glass tank, looking out as a lithe girl performs graceful acrobatics for his benefit. The dolphin stops and is clearly delighted: humans walk on their feet, they don’t usually spring head over heels. It certainly looks as if the dolphin is laughing.

Do animals have a sense of humour? here are experiments that suggest some animals can and do laugh

Hysterical: Suddenly the orangutan opens its mouth wide as if laughing and grabs hold of its foot

The great ape falls backwards in hysterics while maintaining eye contact with the magician

Part of this is because the dolphin’s face looks uncannily like a laughing human. One of the reasons we love dolphins is because they seem to have a permanent smile: but that’s just anatomy. Even though it’s clear the dolphin finds this acrobat’s behaviour fascinating, this isn’t enough to prove scientifically that animals can laugh.

Even my two favourite stories about non-human humour aren’t proof because they, too, are anecdotes, not scientific evidence gleaned from repeated experiments.

Both concern a gorilla called Koko, who lives in California and, it is claimed, can respond to 2,000 spoken words in English, and understand and communicate using 1,000 words in a modified version of American Sign Language.

Koko was asked: ‘What is hard?’ In response, she made a joke — to be more accurate, she made a pun: making the signals for ‘rock’ and ‘work’. She appeared to understand an incongruous connection — both rocks and work being hard — that comes about through language.

Another time Koko was working (hard, no doubt) with her trainer Francine Patterson. She tied Patterson’s shoelaces together — and then signed ‘chase’. Anyone who has played with a four-year-old child can understand the hilarity and daring of this comic effort.

The trouble is that such things can’t really be put to rigid experimental testing, not least because scientific procedure is essentially humourless.

There is, after all, a difference between watching The Morecambe And Wise Christmas Special in laboratory conditions and doing so on your sofa after Christmas dinner with your dear ones and a glass of single malt.

But there are scientific experiments that suggest some animals can and do laugh.

Dr Marina Davila-Ross of the Department of Psychology at Portsmouth University spent years analysing the sounds apes made when they were tickled, and comparing them with human laughter.

Our nearest animal relatives, the chimps and bonobos — who share more than 98 per cent of their DNA with humans — made the noises that were most like human laughter.

Dr Davila-Ross also studied the noises chimps and bonobos made when mucking about with each other — or ‘play-fighting’.

Human children laugh when they indulge in play-fighting. It’s much the same in the archetypal situation of wrestling with or being tickled by your dad. Play-fighting is, for some reason, hilarious.

When chimpanzees play-fight, they pant. They don’t pant in the same way as they do in other contexts, such as when they are exhausted or being bullied — a bullied chimp makes noises that express fear, not fun.

The play-fight panting sounds quite a lot like laughter and what’s more, there is an evolutionary reason for it.

While the young animals are getting lessons in fighting, their laughter makes clear they are not being hurt in the rough-and-tumble. It’s fighting that’s fun and affectionate.

It is unclear whether the orangutan is blown away by the trick or perhaps laughing at its poor quality

The video concludes with the video maker and man laughing as the ape rolls around inside its enclosure

Gorillas and orangutans pant in the same way and science has now shown that all the great apes seem to have something that can be called laughter.

‘The play-fighting serves a very social function,’ says Peter McGraw, a psychologist at the University of Colorado.

‘Some is bonding and some is learning to fight. But what you always see is that the animal being attacked is the one making these vocalisations, which we interpret as laughter.

‘I believe that through evolution, laughter developed as a way of showing that something which would otherwise be wrong is OK.’

And that, surely, shows the link between animal laughter and our own. In humans, laughter has evolved from its play-fighting origins into an essential social tool to express a vast gamut of feelings. But it’s still used to make sense and fun of the incongruous — to show ‘something which would otherwise be wrong is OK’.

Dolphins play-fight, too, and when they do so they make a brief series of sonar pulses followed by a whistle. The sound is never made during serious aggressive encounters. The sound is telling the opponent this is just larking about.

Play-fighting in humans often involves tickling and tickling involves giggling.

This led to a series of experiments at Bowling Green University in Ohio, where they observed that rats make ultra-sonic chirps of pleasure when play-fighting and playing chase.

They then found rats make the same sounds when being tickled. ‘I don’t necessarily call it laughter,’ said researcher Jeffrey Burgdorf. ‘I call it a signal of positive intent.’

A shared response to pleasurable incongruity, friendship and fun doesn’t seem to be restricted to the human species.

Charles Darwin argued that there was ‘no fundamental difference between man and animals in their ability to feel pleasure and pain, happiness and misery’. Put a big stress on the word ‘fundamental’ and you grasp his point.

Whenever you look for a cast-iron certain way of separating humans from all other forms of animals, you find instead a grey area, a no man’s land in which the differences seem muddied and uncertain.

Many animals use complex forms of communication that can be called language. Many solve difficult problems. Some make and use tools. Grief has often been observed. Elephants have been seen burying their dead, vampire bats engage in altruism, humpback whales have culture, bowerbirds create visual art, nightingales compose and perform music.