With its pudgy body, tired eyes and hair loss, the lower mouse could easily be the father of the sprightly and alert animal nestling alongside.
But they are actually the same age, the result of extraordinary trials of drugs which are slowing down or even reversing the ageing process.
Scientists now believe that ageing itself is responsible for many major conditions such as Alzheimer’s, Parkinson’s, arthritis, cancer, heart disease, and diabetes. And they think they have found a way to turn it off.
Anti-ageing drugs - dubbed ‘senolytics’ - are currently being trialled in humans and unlike previous tests which have focussed on a single disease, these drugs work like a broad-spectrum antibiotic, preventing or alleviating most age-related illnesses and frailty.
Scientists at The Mayo Clinic, who first coined the term senolytics, already have six trials in humans under way and plan to start six more shortly. If successful, they estimate that drugs to slow down ageing could be ready within two years.
In mice, the drugs extend lifespan by 36 per cent, the equivalent of adding around 30 years to humans, and crucially the animals remained in good health.
Clinical geriatrician Dr James Kirkland, Director of the Robert and Arlene Kogod Center on Aging at Mayo Clinic, said: “Most people don’t want to live to 130 and feel like they’re 130 but they wouldn’t mind living to 90 or 100 and feel like they’re 60. And now that can actually be achieved in animals.
“Ageing itself is the highest risk factor for most of the chronic diseases. And if you get one age-related disease, you’ve got a huge chance of having several.
“You tend to find older individuals who are completely healthy and are playing 18 rounds of golf a day, or they’ve got three, five or 10 different conditions. There aren’t too many people in between.
“Around 10 years ago we began to explore the notion that ageing may be an upstream cause of all of these conditions and not only be a risk factor but could actually be causal.