April 10, 2013
to be posted on nobabies.net

Larry Elliot and Dan Atkinson
c/o Larry Elliott
The Guardian

Dear Larry Elliott and Dan Atkinson:
I have read your book (Larry Elliott and Dan Atkinson Going South Palgrave MacMillan, New York 2012) and you certainly make a case for the UK needing to accomplish great things lest she slide into the condition of countries we call undeveloped.  As a Southerner I would find it more fun to talk about your choice of title than to get to the point, but I forbear.

The dire issues you raise seem to have one causal thread.  There have been bad decisions regarding the economic setup of the UK.  At the risk of seeming obvious let me trace that process back in time.  Decisions, given an array of opportunities are influenced in great part by age, sex, heredity and childhood environment.  I shall disregard sex.  Heredity and childhood environment are generally determined by which family one is born into.  So the driving force of major events is simply what families have how many children.

Common folly assumes that the number of children a family has is a matter of choice determined by wealth and education.  That question has been specifically addressed by a study in Denmark that found that once factors related to the kinship of the parents and their ancestors were taken into account, there was absolutely no effect of education or income on family size.  The choice concept is now a superstition that has been exploded by science.  For that and my other references you may check out this link:

The relationship is not simple.  A colleague and I find that mammals seem to have two mechanisms that produce infertility in the setting of outbreeding.  One mechanism, which we share at least with fruit flies, is post-zygotic.  That is to say the fertilized egg, the zygote, fails to develop or develops but the offspring has reduced fertility; the extreme example of this is hybrid infertility where two species are crossed but the offspring is infertile.  The second mechanism is pre-zygotic.  That is to say something interferes with the sperm getting together with the egg to form a zygote.  The relationship between the kinship and the infertility is subtly different for the two mechanisms and there is a marked difference in the time course of the fertility as the population size and fertility interact over generations.  This is laid out in a paper we wrote suggesting that this effect might be useful in controlling malaria, which is born by mosquitoes:  Fluctuation of fertility with number in a real insect population and a virtual population
M.L. Herbert& M.G. Lewis  African Entomology 21(1): 119–125 (2013) 

If you take a moment to look at the computer simulations in that paper you will see that the time course of post-zygotic infertility is rather forgiving.  Population size rises rapidly and falls slowly so that the curve “skews left.”  Multiple cycles are possible.  In isolation, the pre-zygotic mechanism is quite blood curdling.  After an initial rise to above sustainable levels the population declines, seems to be leveling off, and then the bottom drops out.  It appears that in real life the pre-zygotic mechanism “saturates”; it can do only so much harm.  And it takes longer to have a significant effect.  But once it cuts in the change appears to be abrupt and, added to the already extant post-zygotic mechanism, lethal.

You may think that fertility is not germane to your interests, but of course it is absolutely central.  What families have babies and how many is the driving force of society.  In recent generations productive people have not chosen to marry sufficiently close kin.  The result has been that they find they cannot choose to have enough children to replace themselves. 

I have no agenda.  I do not know how one might change things for the better.  Nor do I have a serious proposal for which generation will see fertility in the developed world undergo abrupt collapse, although all evidence suggests the current century, and if I had to wager I would bet that the last fertile females have already been born.  But I think I have a clue about what is going on or at least am asking an important question.  And if you want to fix anything, understanding it is a jolly good place to start.  So what do you think?


M. Linton Herbert

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