August 26, 2011

111 West 57th Street
NY, NY 10019

Dear Sir:
I read with due alarm your articles on the falling marriage rate and rising marriage age in Asia.  (Asia’s Lonely Hearts ECONOMIST vol. 400 no. 8747 August 20, 2011 page 9 and The Flight from Marriage, page 21 in the same issue.)  I sense unease on your part.  Citing some Japanese statistics you say, “… for what it is worth …”   In many years of being your reader I never remember you treading with such care.  Then there is the phrase, “… extremely disturbing …” Against the calamities of the past decade something evidently is standing out. 

From what I gather, sex selective abortions have produced an enormous excess of young males over females in India and China.  Compounding that, in China at least, is a large number of well educated women who will not marry at all or marry only those equally well educated, leaving an ever greater unmarried excess at the bottom of the economic scale.  I suppose this alone could cause social and political instability, but I have been unmarried longer than most people have been alive and I swear I have never overthrown a single government.

But given the size of the male excess and given the size of the two nations there will be enormous pressure to bring wives in from abroad.  You might call it poaching.  In America at least this poaching already goes on.  Attitudes toward it are so indifferent that I have never even seen an estimate of the numbers. 

Of course the difference is that poached brides in and from rich countries are probably acting under their own volition while this is less often true than for the brides bound for the Asian giant powers.  Still, they may not have been totally free at home, and the match might be a step up economically for them.  Any change entails risk so I suspect the reason for your dark foreboding must be uncertainty about the cause.   

There is evidence for a cause you have not considered.  There was an article (An Association Between Kinship And Fertility of Human Couples.  Agnar Helgason, Snaebjoern Palsson, Daniel F. Guobjartsson, Pordur Kristjansson and Karl Stefanson, SCIENCE vol 329 8 February 2008 page 813) that showed that normal fertility required cousins marrying, and that this kinship needs to be fairly close, within sixth cousin, for a stable population.  The article is hardly obscure; it was reviewed in ECONOMIST.  The kinship element so strongly constrains fertility that there is very little room for any other factor.  It is obvious that there is some irresistible mechanism in play.

There is a relationship between age at marriage and number of offspring, but it is not the intuitive one.  In the absence of numbers one might be forgiven for thinking that later marriage causes fewer babies.  But the study does not allow for that.  And if you look at the numbers there is a surprise.

I looked at and compared birth rate with age at first marriage followed over time.  The two do not, in fact, move in concordance.  Instead there is a very characteristic pattern by which fertility falls while age at first marriage remains constant.  Then as the fertility falls below replacement, it stabilizes and age at first marriage abruptly starts to rise.  Obviously this is not a stable situation.  Something must give.  And what happens next is not clear.  No country has gone far enough.  Of course the most developed countries have their birth rates boosted by in vitro fertilization, but the extent of this and the degree to which it produces fertile people are to me unknown.  There may be cold comfort there.

Since fertility seems clearly to be determined by a mechanism, and since the rise in marriage age begins the instant the fall in fertility stops, I strongly suspect that there is a mechanism altering the biological clocks of women, and it must perforce be governed by kinship, if after a delay of a generation or more.  And cousin marriages are becoming an ever greater rarity. 

Go ahead, look at the numbers.  They may make your day no brighter, but I assure you they will make your day more interesting.


M. Linton Herbert MD

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