The moment Joy Milne and her husband Les entered the room, the mystery that had puzzled her for over a decade was solved. Les had been diagnosed with Parkinson's disease, and they had come to their first support-group meeting. "We were late," she remembers. "A lot of people were there. And I walked into the room and I thought, 'SMELL!'"¹

The scent of Les's body had been one of the things that first attracted her to him: "He had a lovely male muskA substance with a strong sweet smell that originally came from Musk deer. It is used in perfumes. smell. He really did."

The two married after college; Les became a doctor and Joy a nurse. But 10 years later Joy suddenly noticed something different about her husband. He had started giving off "this overpowering sort of nasty yeastA tiny fungus that can change sugar into alcohol and carbon dioxide. It is also used in bread-making. smell". It kept getting stronger - and at the same time, his personality began to change: "He was more moody. He wasn't as tolerant."

By the age of 45, he seemed a completely different person. Finally, after a frightening episode in which he attacked her in his sleep, they went to see a doctor. He told them Les had Parkinson's.   

At the support group the penny finally dropped. Joy realised that everyone suffering from the disease had the same "greasy, musty" smell. And she and Les immediately recognised the importance of her discovery: here was a chance to detect the disease in its early stages, before it had seriously damaged the brain.

When the couple told a researcher at Edinburgh University, Tilo Kunath, he initially refused to believe them. But then he heard about the discovery that dogs could smell cancer, and asked Joy to come back for an experiment.

Kunath asked a group of people with Parkinson's and another group without it to wear new T-shirts overnight. Then he asked Joy to smell them and tell him which shirts came from each group. "She was incredibly accurate," he says.

Kunath and his colleagues set about discovering which chemicals produced by the skin were responsible for the smell. Now researchers at Manchester University have developed a test which they claim can detect the disease in three minutes.

Joy Milne is not alone in having powers that seem superhuman. They range from Thai Ngoc, a Vietnamese man who has not slept since 1973, to Wim Hof, the Dutch athlete known as "The Iceman" because of his ability to cope with extremely low temperatures.

Jo Cameron, a retired lecturer from Scotland, has a genetic mutation which means that she never feels pain or anxiety. Rebecca Sharrock from BrisbaneThe third-largest city in Australia, situated on the east coast. has a condition called Highly Superior Autobiographical Memory, meaning that she can remember everything that has happened to her, right back to the age of one.

American Scott Flansburg is known as "the fastest human calculator" because of his brilliance at mental arithmetic.

But superpowers can have drawbacks. Psychologist Justin Feinstein worked with a woman who felt no fear. The problem was that she could find herself in dangerous situations without recognising the threat. "I wouldn't wish it upon anyone," she said.²

Yes: We can all do extraordinary things if we train our minds and bodies in the right way. Tibetan monks can raise their body temperatures to withstand intense cold just by meditating.

No: Most "superpowers" result from genetic mutations or damage to particular parts of the brain. Only a very small number of people in the entire world are likely to experience these.   

Or... It all depends how you define "powers". Everybody is good at something, and in some cases it is obvious from an early age. But other people only stumble upon their gifts later and by accident.

Musk - A substance with a strong sweet smell that originally came from Musk deer. It is used in perfumes.

Yeast - A tiny fungus that can change sugar into alcohol and carbon dioxide. It is also used in bread-making.

Brisbane - The third-largest city in Australia, situated on the east coast.