Wednesday, May 16, 2018

Falling fertility rates shouldn't be a problem forever

There are a lot of countries in the world with declining populations.  Historically this isn't unusual if there's famine or disease or war causing it but in the developed world this is mostly just people choosing to have fewer children.  In Japan it's all the way down to 1.46 children per woman which, since half of kids are male, means that every generation will tend to be three quarters as large as the one before it.

There are a lot of reasons for this.  People having better options than they did in the past seems like the biggest one.  There are differences within the industrialized world in many ways involving religionattitudes towards child care, and other thing.

But those are societal factors and there are also individual factors at play in a couple's decision to have kids.  People have different personalities and personality seems to have an effect on child bearing just like you'd expect.  Here's a study I recently saw linked on twitter.

So, for instance, people who are more Agreeable based on the Big Five personality traits social scientists normally use seem to be more likely to have children.  And these personality traits seem to be substantially heritable.  So if nothing were to change we should probably expect evolution to have its say and the population decline to eventually halt and reverse itself through natural means.

I don't actually expect things to turn out that way.  Rather, I expect technological improvements in the ease of having and raising children to make a bigger difference sooner.  And societal improvements would be nice too but I'm not counting on those.  How we're going to take care of large numbers of older people as they live longer without a large working population is going to be a concern for the next few generations but there's no reason to worry about humanity going extinct or anything.

Of course technological progress cuts both ways and maybe virtual reality will reduce childbearing rates further.  But again I expect the next generation being more like the sort of people who had kids in the last generation to eventually rescue things.

But the sad moral of the story is that we might have we might have gotten out of the Malthusalian trap.  Maybe even for quite a while.  But I'm pretty sure that in the very long run the human population will increase again until it's reduced to a subsistence level. 

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