More evidence that girls are better:
This week's issue of Nature has an article about how pollution increases the probability of girls being born in that area. In addition,
"Research shows that natural disasters and crises such as terrorist attacks can increase the probability that a newborn is female."
Why would this be?
According to the article, there are two possiblities:
1. "This is thought to be the safer reproductive bet, as girls are likely to grow up and have a few children of their own. Boys are a more risky venture: they could father dozens of children, or none at all."
2. Boys are the weaker sex: "...some scientists speculate that Y-chromosome sperm, which will produce boys, are weaker than X-chromosome sperm, and therefore more susceptible to environmental stresses. But that has not actually been proven..."
I venture a third option:
3. GIRLS ARE SMARTER, PRETTIER, and REQUIRE FEWER RESOURCES, therefore are better able to survive and overturn challenging circumstances.