You know what it’s like. You walk into a bar. You gaze around the room. You try to hide the embarrassment that’s written on your face. And then you spot a man in the corner. He is hunched. He is lined. He is grey. He looks up. His eyes light up.

Your heart sinks.

If you’re a woman over 40 who has tried internet dating, you have probably been here at least once. The photo is fine. Or at least the photo is OK. He is not George Clooney. But you are not Scarlett Johansson, and you are not 25. Look, he has, or seems to have, his own hair. He has, or seems to have, his own teeth. What you didn’t realise, when you looked at his profile and decided to give him a chance, was that the photo had been taken 20 years before.

I was first told that I was “past my peak” by a dating agency when I was 36. Men my age, they said, wanted younger women, who wouldn’t force them into commitment or panic about their eggs. I should, in other words, be grateful for any oddball who would take me on. A decent man – one with, say, some friends and a job – would be able to take his pick of the twentysomethings with fresh faces and wombs that weren’t ticking bombs.

Sure, it wasn’t fair, but biology isn’t fair. God told Eve that she was basically a breeding machine who would suffer agony in childbirth and Adam that he could, in effect, sign up to Tinder and have decades of stress-free fun.

And so, all around us, we see the results: elderly film stars, rock stars, chief executives and politicians brandishing their babies and their much, much younger wives. Ronnie Wood, at 68. Rupert Murdoch, at 72. Mick Jagger, at 73. Look at me! I’ve still got it, and it’s huge! What they are talking about, of course, is their wallet. The older a father is, the richer he’s likely to be. Rich men have purchasing power, and if the price of youth and beauty is a late-in-life kid, well, they can afford it. They do it because they can.

Or perhaps we should say they did it because they could. I’ve got news for you, gentlemen. Your days of infinite browsing in the giant Amazon warehouse of gorgeous women may be numbered. There we all were, thinking that you just had to pick the moment, and the girl, to ditch the canapés for the sit-down meal. If you picked well, your mighty sperm would hit the spot and do the job. Hey presto! Happy families! But here’s the bad news: sperm goes off.

From the age of 40, according to the most recent research, a man’s fertility declines. It can take five times as long to conceive with a male partner over the age of 45 than with one under 25. The risk of miscarriage is much higher. And any child you have is five times more likely to have an autism spectrum disorder and 13 times more likely to be diagnosed with ADHD.

We are not talking gender equality here, any more than we are in pay. A woman’s fertility starts to decline in her early 30s. At 35, it starts to decline more rapidly. That dating agency was factually correct in saying that, at 36, I was “passed my peak”. But what is clear from this research is that it isn’t just women who are facing a ticking clock.

Infertility breaks hearts. I’ve interviewed both men and women who have wanted to have a family, and have had to face up to the fact that they can’t. The stories of the men I spoke to were just as painful as those of the women. Often the issue is biological, but sometimes people just don’t find the right partner at the right time. I didn’t. Many women don’t. But nor do quite a few men.

Perhaps this research will remind us that we all need to be a bit more honest about the choices we face. Do we wait for Barack Obama or Angelina Jolie, or go with Mr or Ms Good Enough?

Do we go for the healthy baby in the rented flat or risk no baby by waiting for the mortgage or the house? Do we, in other words, live in the world as we would like it to be, or the world as it is?

And if, for example, you’re a man who is now a bit tired and paunchy, do you carry on chasing women 20 years younger and assume they will be thrilled? Or do you look in a mirror and think: you know what, I’m past my peak. I think I’ll start looking at women my own age.