A couple of months ago, I was in my 73-year-old mother’s back garden, scrolling through her matches on an online dating site and discussing ways she could meet a prospective partner without getting within sneezing distance of him. As you do, in 2020. 

I came across a sprightly-looking, tennis-playing 78-year-old, who I thought could be just the ticket. She protested that he was too old, though, and instead decided to meet up with a 70-year-old man who I thought rather less sprightly-looking. I was proved right: he turned out to be too elderly for my bicycle-riding, dance floor-dominating mother.

But it got me thinking: once we’re past a certain threshold, wouldn’t it make more sense for us to think about age in terms of how long we’re likely to have left, rather than how many times we’ve spun around the sun? The athletic 78-year-old could well have another 20 years in him; the doddery 70-year-old perhaps 10.