Picture two boxes of mice. In box one, the mice sluggishly ramble around. In the other they run wild.

This might not seem like big news. But it could be the start of something huge.

Researchers at Imperial College London have discovered a way to slow the effects of ageing in mice.

They suppressed the geneA gene is the basic unit of heredity. that produces the proteinLarge biomolecules made of up amino acids, which in turn are made up of DNA. interleukin-11.¹ This improved their senses, muscle function and metabolismThe chemical processes within the body which produce energy. It derives from a Greek word meaning "change".. It prevented cancer. It let them live 25% longer lives.² And it allowed them to keep their glossy dark fur. No more grey hair or balding.

Humans also make interleukin-11.³ The new process might have the same effect on us. Trials have already begun.

Extended youth is on the horizon. Maybe eternal youth will follow.

Humans are obsessed with beating ageing. Legendary heroes quested for the Holy Grail. Today we cover our faces in expensive creams made from such ingredients as crushed insects and snail slime.

In 2016, tech billionaire Peter Thiel made headlines for claiming he wanted to inject young blood into his own body.⁴

Imagine a life where we never start to slow down. We would be full of energy. Our joints and limbs never ache. Injuries would heal so quickly. We could play our favourite sports forever.

Think of the other benefits. Hospitals are crammed with elderly people.⁵ Eternal youth would clear the waiting lists.

Yet some say that mortality pushes us towards greatness. If Carlos Alcaraz had his current fitness forever, would he push himself so hard today?

Being young can be hard work. "Old age, believe me, is a good and pleasant thing," said Ancient Chinese philosopher Confucius. "It is true you are gently shouldered off the stage, but then you are given such a comfortable front stall as a spectator."

Of course Confucius did not enjoy eternal youth. If he had, maybe he would have thought differently.

Would you want to be young forever?

Yes: Only a fool would say no. Imagine: an endless life at the peak of health. The world would be your oyster. You could try out hundreds of different lives, never rushing blindly down a single path.

No: Eternal youth is definitely better than eternal ageing. But it is still a curse in disguise. Maturing is one of life's most interesting experiences. And we would lose any sense of youth's specialness.

Or... Youth is overrated. The real prime of life comes later. If you had to live forever, surely you would want to be in your 30s or 40s: young enough to be dynamic, old enough to be respected.