The longevity of the Beatles’ music is a phenomenon; the release of Now and Then a reminder of lyrics that still provide soulful commentary and the tunes that are giving us a knight to remember across Australia.

But Sir Paul McCartney, at 81, is the elixir of life; singing, dancing and witty proof that the twilight years need not be what they once were.

And perhaps that’s the message we need to sell the nation’s baby boomers – 80 is the new 60.

That doesn’t mean that at 80, with heads sometimes as shiny as shoes, our octogenarians need to turn up at the office each day.

But it does mean that those distinct stages of life, that have coloured earlier generations, have now been muted. When I’m Sixty Four has never seemed so good.

Theories on adulthood have always revolved around young adults, and then middle adults, or those aged in their mid-30s to the mid-60s. Then, it’s late adulthood or old age. People have been herded into a category, based on age.

Or at least that once was the case, with ‘old age’ characterised by a newly minted Seniors Card, declining physical and mental abilities, a pursuit of more gentle interests, and in recent years, a spot of caring for the grandchildren.

Paul McCartney has used his multi-state Australian tour to remind us that like him, we are Getting Better with age.

It’s a lesson on show in other arenas around the world.

Harrison Ford is the same age – 81. And the Indiana Jones and the Dial of Destiny star recently announced that retiring was not a possibility.

Martin Scorsese turns 81 in a fortnight, and his new epic Killers of the Flower Moon shows he has no intention to down directing tools, or casting according to talent, not age (as evidenced by 80-year-old Robert De Niro).

The Rolling Stones have released their first album of new material in 18 years, with Mick Jagger and Keith Richards both turning 80 this year.

And Joe Biden might not showcase the same adventurous leg kicks as McCartney, but is planning another round of Capital Hill – and he turns 81 this month.

At 92, Rupert Murdoch has finally agreed to hand over his pencil.

This new energy, into our 80s, was unheard of a decade or two ago. And that’s because the stages of life kicked in. We moved from young adult to middle adult, then old adult. Then death.

Disruption, thank goodness, has turned age on its head, and while life expectancy remains in its very early 80s for men, and slightly higher for women, how we spend our ‘Old Age’ is no longer prescribed.

Those distinct age stages have disappeared.

Middle age, for many, can run into their 80s. No longer is 65 a full stop on a productive working career. It’s a transition we can accept. Or not.

In part, that’s medicine. In part, it’s lifestyle. In part, it’s socio-economic status, perhaps. But seeing is believing, and McCartney’s ability to belt out a 39-song set to screaming fans is a signal to his 81-year-old peers – and the rest of us – of what is possible.

This is a lesson for policy makers too; a point made by the World Health Organisation last year. “Older people are often assumed to be frail or dependent and a burden to society,’’ it said.

And public health professionals, as well as communities at large, needed to address those “ageist attitudes’’ that could lead to “discrimination, affect the way policies are developed and the opportunities older people have to experience healthy ageing’’.

Or perhaps the cheaper option is to Let it Be, and just pop along to concert where an 81-year-old music legend can bring unbridled joy across songs and generations and dance moves.

May his chair keeping rockin’.