The mystery was finally solved. Les and Joy Milne had come to their first Parkinson's disease support-group meeting. "We were late," Joy 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."

But when Les was 31, he started giving off an "overpowering sort of nasty yeastA tiny fungus that can change sugar into alcohol and carbon dioxide. It is also used in bread-making. smell." And his personality began to change: "He was more moody. He wasn't as tolerant."

By 45, he seemed a completely different person. Finally, a doctor told them Les had Parkinson's.  

At the support group, Joy realised that everyone with the disease had the same "greasy, musty" smell. It was a vital discovery: a chance to detect the disease before it did serious damage.

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

Kunath asked a group of people with Parkinson's to wear new T-shirts overnight. He asked the same of a healthy group. Then he asked Joy to smell the shirts and tell him which ones came from each group. "She was incredibly accurate," he says.

Kunath set about discovering which chemicals produced by the skin caused the smell. Now researchers at Manchester University have developed a test to spot the disease in three minutes.

Other people have 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 withstand cold.

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 ever happened to her.

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.