John Byrne Murdoch

had fewer children or had less sex than others.

Another study found that people who watched TV shows centered around families that had few children had fewer children themselves.

So this is not some kind of exotic smartphone-specific theory.

It's something that people have been talking about and finding evidence for for a long time.

The fundamental issue here is that when countries have very low fertility rates, so in the sort of 1.5 and below range that a lot of these countries are now in, you have big problems coming down the track.

Living standards are a function of how much stuff is being produced in your economy divided by the number of people in that economy.

Now, if you start having fewer people born, you will then have fewer people working.

The share of your population producing stuff, in crude terms, is going to get smaller.

And that means even if the amount type quality of work that all your workers are doing stays the same, the amount of stuff to be shared out across your population will go down.

So Japan is really the canary in the coal mine here.

Japanese workers produce just as much today as they did 30 years ago.

But there are significantly fewer Japanese workers as a share of the population than there used to be.

And that has put significant downward pressure on Japanese living standards.

And that is the result that could be coming to a huge number of countries, not only in the rich world, but now in middle income world as well.

None of these policies are likely to get us back up to people averaging two kids per family, but they are maybe able to stop the decline going quite as steeply.

If people are currently struggling to juggle work and childcare and anything we can do to make that juggling act easier is clearly a good thing.

And there's good evidence as well that these policies do have positive impact.

But more broadly, I do think

it will be interesting to look at the medium-term impact of some of the policies reducing screen time.

For example, to Australian teenagers who are currently going through those restrictions, what do their lives like, their relationships, their social lives, everything else look like in 10 years?