Humour in most men may develop from aggression and it all begins at puberty, researchers say.
Researchers at Newcastle University studied the reactions of men and women on seeing a trick cyclist and the results revealed huge differences between male and female response.
Nine out of 10 women would make warm, kind and encouraging remarks, while young children showed interest and curiosity.
But as boys grew older, their reactions became increasingly unpleasant. Curiosity typically turned into physical and verbal aggression, and they would throw stones or attempt to obstruct the rider by shouting, "Fall off!" the Independent reported.
Grown men suppressed the urge to injure the rider, but became sarcastic and aggressive, and would often make jokes about the single wheel.
Professor Sam Shuster of Newcastle University, who rides a unicycle, analysed data from more than 30 unicyclists aged between 15 and 69, from the UK and across the world, with up to 40 years' experience.
He found a surprising consistency of responses from boys and men, irrespective of social class, geography or era, which indicated a common biological mechanism.
Changes in male hormones, which are associated with aggression, around the time of puberty, are perhaps responsible for this.
"The consistent response to seeing a unicyclist is related to sexual development, suggesting that humour develops from aggression in males," he said.
It also signifies other links between aggression and humour.
"Laughter associated with tickle, considered by some to be the origin of humour, is neurologically related to pain and moves easily into agony."
"A relationship between humour and aggression may also help explain the enjoyment of practical jokes, 'gallows humour' and the humour of verbal combat, whether over the dinner table or on the football terrace, where its enjoyment can relate to the discomfort it causes," Professor Shuster added.
The study has been published in the Journal of Psychology Research and Behaviour Management.