April 12, 2010

Alan Tapper
Edith Cowan University (ECU)
270 Joondalup Dr.
Joondalup WA 6027
13 4328

Dear Dr. Tapper:
I appreciated your contribution to the documentary “Demographic Winter.”  You mentioned that families by and large are not in a position to compete in the boisterous environment of politics.  Politicians are more likely to listen to those staging marches and bolding signs than to the quiet workings of families upon whom everyone else must depend for survival.  I agree that this is lamentable.

While I was looking up your address, a couple of other things came to my attention.  You were already concerned about this in 2002.  It was not long after that that I attended my first genetics conference, which was in Melbourne.  If you were in Perth at the time and I had known it I would have begged for a chance to meet you. 

I noticed that you said the point of no return seems to be about 1.5 children per woman.  That is very interesting.  I think there really is a point of no return, but I cannot really demonstrate it.  Here are some numbers from a computer simulation I did.  Using assumptions that seem to be backed up by real biology I created a virtual population and let it run to see how many offspring there would be per generation.  The population was limited to 20,000, all my poor desk top can handle given the other demands of the program.  The population went sky high, crashed, recovered again only to skyrocket and then go extinct.  These numbers are from the minimum.

1735  1285  991    698    483    320    208    142    87      57      41     21       14      8        11      6          7        10      7        13      25      52     117     297    727    1821  4411  10531 24757

As you can see we are in broad agreement about the point of no return.  My population was dropping somewhat faster than it would at a fertility rate of 1.5 but close enough, as they say, for government work.  The thing that strikes me most is that the precipitous decline does not level off until the total population is below 10.  Now technically speaking 10 is not extinct.  But a world population of 10 would be very vulnerable.  A single rabid dog could take it down. 

The graph from which these numbers are taken is at NoBabies.net put up on March 25, 2010.  The site contains other material including letters like this.    

Also in the material I ran across was a remark by you that we lack good theories to guide policy and are having to scramble to work it out.  Well I used to be a motorcyclist and to me a scramble is a motorcycle race across very rugged terrain.  It is slower than a track race but generally faster than walking.  I have been moving slower than a walk, but I have been doing my best since a few years before 2002. 

So here is what I want to show you.  Go to that website I mentioned and look at my theory.  I think you will find it is supported by evidence of extent and variety far beyond what anyone, even I, ever expected from the social sciences.  If you then entertain a shadow of a doubt, get in touch with me.

I hesitate to give you the bottom line, because I think a lot of people use it as an excuse not to think about the matter.  But the fact is that little villages have more babies per couple than big cities for a very good reason.  A big population suppresses fertility.

Please let me know what you think.


M. Linton Hebert MD

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