Cross border marriages:
Sometimes people from different countries marry. (Herr and Madame, Senor and Mrs ECONOMIST vol. 401 no. 8758 November 12, 2011 page 67) It happens a lot, but national boundaries have no biological meaning and so the phenomenon is neither here nor there in terms of our interest in fertility. Still one notices when a major journal takes an interest.
The numbers are difficult to get at because of ambiguities of definition. Spain and Italy have high rates and of course they have low fertility, so maybe there is a hint of a biological impact. Cypress is the champion where three quarters of marriages are between mutual foreigners, up from about a half in 1995. Yes the fertility is not that different from other developed countries. Looking at gapminder.com it appears that fertility has fallen over the same period, but age at first marriage has not changed much. The article says that a lot of foreigners come to Cypress to marry since it is the traditional birthplace of Venus, and this distorts the statistics.
Asian men seek foreign wives in hopes of having more children. Oops. (Marrying outside your country does not mean failing to marry a cousin, but it can’t help on average.) Actually this seems to be born out in Europe and America, where fresh immigrants are indeed more fertile although the effect fades over a few years; I would have expected it to be a few generations. In fact in Korea the immigrant wives appear to be less fertile even than native born. And wives from China appear to have very low fertility. Listen. Do you hear the penny drop? Do you hear them saying, “Oh my goodness. It looks like the “one child policy” in China is not the cause of the one child families”? I don’t.
There are issues that arise such as whether men importing brides are older, richer and better educated than their peers. There is also the question of whether women taking the plunge to move and marry can expect good treatment. Well I don’t have anything new to say about that.
Oddly, both in Korea and Europe the children of trans-national marriages tend to have worse health. In Europe and Taiwan they do less well in school. I cannot say what that means. The data has already been cherry picked and a second round of selection to make some point would seem idle.
It does seem that international matches last longer. I would expect that. Whoever moves to a foreign country abandons a support structure; this would make leaving the marriage more difficult.
So there is no great breakthrough in people’s understanding or mine, although there might be something hiding in the data that one more skilled in the art than I might be able to draw forth.
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