Population predictions are crap

What I want to say here is mostly 4th grade stuff but vast numbers of people don't seem to get it.

What I want to talk about is the folly of straight line projections.  People who are used to graphs should know immediately what I am going to say but people with more  literary inclinations probably will not.

Perhaps the most hilarious example of the folly concerned is the repeated prediction that we are going to run out of oil soon.  People have been making that prediction ever since oil was discovered and they have always been wrong.  Up until fracking was implemented, Greenies used to make that prediction.  But fracking has mostly silenced them on that issue.  Now they say we will run out of food!

So why has that prediction always been wrong?  Because it assumes that all the influences on the thing concerned will stay the same. In the case of oil, it assumes there will be no more discoveries.  The reasoning goes like this:  "We have reserves of 10,000 barrels of oil and we are using 1,000 barrels each year so therefore we will run out in 10 years".

It's great arithmetic but totally ignorant of almost everything in nature.  Nature is complex.  Things are always changing.  And if there is any predictability at all in nature the trend will be in the form of an ogive or some other curvilinear trend.  In an ogive, things rise for a while and then flatten out.  In statisticians' terms, they "approach an asymptote".

So it should by now be clear why all the current  predictions of future population will be wrong.  I am in fact here and now going to issue a prophecy!  Bold, I know, but it's a pretty safe one. And neither the Book of Daniel nor the Book of Revelation is involved!  So: This is my prophecy:

"In 50 years time, all the current predictions of various national populations will be shown to have been wrong"

The birthrates in various nations at the moment are very low.  So low that the straight-line wise-heads are predicting that the populations of countries like Japan, Italy and Russia will be only half of what they are now.  Why is that prediction foolish?  Because it assumes that birthrates will remain the same.  Yet anybody who remembers the world before the 1960s should know how absurd that is.

Take Italy, one of the doomed populations according to the straight-line wiseheads. Italy was once the land of large families.  Lots of Italian families had an Ottorino (eighth child).  Now, of course, one child is the norm.  So does not a change as drastic as that tell you something?  Does it not tell you that all the influences on the given phenomenon (in this case the birthrate) will NOT remain the same?  It surely should.

Let us be a little more insightful about population than doing silly arithmetic.  What caused the Italian birthrate collapse?  The same thing that has caused a birthrate collapse in most of the developed world:  The contraceptive pill. Children are expensive but up until about 1960 people had no easy way of stopping them coming.  So they kept coming.

OK.  The pill was an unexpected factor that threw out all the straight line "population explosion" projections made in the early  20th century.  Paul Ehrlich take a bow.  So what other influences could come along and ditch all the present predictions?

There is an obvious one: An evolutionary one. All the non-maternal women are currently being removed from the gene pool by reason of the simple fact that they now rarely have children. Women like them will become rarer and rarer. So all the births of the not too distant future will come from maternally-inclined women. And how many children will those women have? As many as they can afford (and then some in some cases). Some wonderful stories about maternal women here and here and here and here and here.

So the birthrates in advanced nations will recover and the  population will start growing again -- albeit off a lower base.

And there are other influences that may have an effect -- even ones that I have not thought of!  France, for instance, has long had pro-natalist government policies and that has propped up the French birthrate.  Similar policies will probably be adopted by other nations.  Russia and Singapore have already stepped up to the plate with policies of that nature.

And here's a way-out one:  It seems to have become fashionable for celebrity women to have children, multiple children in most cases.  You would not think that women who live by their looks would risk  their figures by having children, but they are in fact doing it -- the Kardashians, for instance.  Children now seem to have become a sign of affluence.  They are the ultimate luxury -- even better than big yachts and Gulfstream jets.  And lots of people DO emulate celebrities.  Many women in the near future may start having children because it is fashionable or simply because they want to show off.  One can imagine the conversations:  "I've got three.  How many have you got?"

So who knows what the future holds?

Posted by John J. Ray (M.A.; Ph.D.).