our "patriarchal society" Do dads react differently to sons than to daughters? You better believe it!

On average, Lundberg and Rose said, the birth of a child increases a man's wage rate by 4.2 percent and his annual time at work by 38 hours compared with a childless man, controlling for other relevant factors. [...] Then Rose and Lundberg wondered if the baby's sex made a difference. It did, and the differences were huge: Men worked about 118 hours a year more if their first child was a boy but only 54 hours more if their first-born was a girl. The pattern was the same regardless of birth order.

But there's more:

Spurred to dig deeper into the data, Lundberg recently discovered an unmarried mother is about 25 percent more likely to marry the father of her baby if the child is a boy than if it is a girl. Other researchers have found marriage-survival rates 7 percent higher with a son than with a daughter.

This working paper dismisses hypotheses that perhaps sons provide better "returns" on money spent on education, or that perhaps daughters are more likely to provide for parents in their old age -- neither seems to explain the data. Instead, it appears,

Men appear to place a higher value on marriage and their family and seem to be more willing to make a bigger investment in their family if they have sons.

Now, how to understand this? Some evolutionary psychologists believe that there is a human inclination towards selective neonaticide. A weaker belief would be simply that new parents do some sort of (unconscious) cost-benefit analysis and (systematically) adjust their behavior accordingly. But why do fathers benefit disproportionately from male children? Is it just a function of our "patriarchal society"? Or is there some deeper evolutionary cause? Update: Paul Orwin suggests that fathers benefit when sons carry on their name. I like this explanation, as it accounts for both the mother/father and son/daughter differences. It would be interesting to see if the effect is more/less/as pronounced among couples who keep their names. Incidentally, two keeping-our-last-names married friends of mine are expecting their first child shortly, and last week I asked them what the baby's last name was going to be. Apparently this was a highly sensitive (and unresolved) topic, and I was told to drop the subject. :)