An Evolutionary Explanation for the Returning Soldier Effect

In The Red Queen (p. 123), Matt Ridley claims that it is well-established that "during and immediately after major wars, more sons are born than usual in the belligerent countries as if to replace the men that died". He says this "would make little sense", and that "finding the logic in this...is beyond most scientists at this stage".

Yet an explanation becomes readily available when one combines:

1. My suggestion that the sex ratio of 1 does not preclude the proliferation of mutations that favor one gender over another , as long as there is an equal and opposite proliferation of mutations that favor the opposite one. Thus, the fact that the ratio is 1:1 may be hiding families with genetic predisposition toward male or female progeny.

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2. The fact that in a polygamous species, dominant males who produce progeny biased towards males will be selected for (Ridley: The Red Queen, pp. 112-114).

During and after a war, the shortage of men makes humans more polygamous than usual, with dominant males left alive, whose genotypes favor male progeny, more likely to inseminate multiple women left available (and willing to accept a mate who is not a husband) by the shortage of men due to the war.

Note the fact that the finding applies during the war, and not just after the war, suggests that the effect likely involves children born, and likely conceived, while their husbands are off at war --I would venture without the husbands' knowledge, consent or participation.

A competing explanation by Valerie Grant postulates hormonal effects in mothers. She found that women who gave birth to boys tend to be more dominant in personality during pregnancy than women who gave birth to girls. If women behave more dominant during wars, that could explain the Returning Soldier effect. Which, incidentally, might be more aptly named the Absent Soldier effect.